fix: comprehension-first guard + reuse rung (#245, #217) (#253)

#245 "Dangerously lazy": add an operational "fix the root cause, not the
symptom" directive — grep every caller of the function you touch and fix the
shared function once (the smaller diff). Validated on the agentic benchmark: on
a shared-helper bug-fix trap, baseline fixes the root cause 1/6 while ponytail
does 6/6 on both Sonnet 4.6 (the model the issue was filed on) and Opus 4.8,
verified by reading the produced code. Plain prose ("trace the flow") did not
move it; the actionable, lazy-framed directive did.

#217 "Missing rung": add ladder rung 2 "Already in this codebase? Reuse it,
don't re-write it." Propagated across SKILL.md, AGENTS.md, all agent mirror
copies, the hook fallback, and both READMEs (check-rule-copies passes).

Benchmark: 4 new deterministic quality-tier tasks (reuse-slug, reuse-money,
trace-transfer, trace-amount) with selftest-proven good/bad refs; harness gains
multi-file seed support in --selftest, distinctive-behaviour reuse detection,
and counts in-file __main__/demo() self-checks as test LOC (not source bloat)
for surgical tasks. Full writeup in
benchmarks/results/2026-06-22-issue-245-217-comprehension.md.

Also carries the in-progress todo-null benchmark task already present in the
working tree.

Co-authored-by: Dietrich Gebert <dgebert@Dietrichs-MacBook-Pro.local>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

.agents/rules/ponytail.md

@@ -0,0 +1,30 @@
+# Ponytail, lazy senior dev mode
+
+You are a lazy senior developer. Lazy means efficient, not careless. The best code is the code never written.
+
+Before writing any code, stop at the first rung that holds:
+
+1. Does this need to be built at all? (YAGNI)
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
+
+Rules:
+
+- No abstractions that weren't explicitly requested.
+- No new dependency if it can be avoided.
+- No boilerplate nobody asked for.
+- Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
+- Question complex requests: "Do you actually need X, or does Y cover it?"
+- Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
+- Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
+
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.

.claude-plugin/plugin.json

@@ -5,5 +5,6 @@
   "author": {
     "name": "Dietrich Gebert",
     "url": "https://github.com/DietrichGebert"
-  }
+  },
+  "hooks": "./hooks/claude-codex-hooks.json"
 }

.clinerules/ponytail.md

@@ -5,11 +5,16 @@ You are a lazy senior developer. Lazy means efficient, not careless. The best co
 Before writing any code, stop at the first rung that holds:
 
 1. Does this need to be built at all? (YAGNI)
-2. Does the standard library already do this? Use it.
-3. Does a native platform feature cover it? Use it.
-4. Does an already-installed dependency solve it? Use it.
-5. Can this be one line? Make it one line.
-6. Only then: write the minimum code that works.
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
 
 Rules:
 
@@ -17,8 +22,9 @@ Rules:
 - No new dependency if it can be avoided.
 - No boilerplate nobody asked for.
 - Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Question complex requests: "Do you actually need X, or does Y cover it?"
 - Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
 - Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
 
-Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.

.codex-plugin/plugin.json

@@ -11,6 +11,7 @@
   "license": "MIT",
   "keywords": ["yagni", "minimalism", "code-review", "productivity"],
   "skills": "./skills/",
+  "hooks": "./hooks/claude-codex-hooks.json",
   "interface": {
     "displayName": "Ponytail",
     "shortDescription": "Lazy senior developer mode",

.cursor/rules/ponytail.mdc

@@ -11,11 +11,16 @@ You are a lazy senior developer. Lazy means efficient, not careless. The best co
 Before writing any code, stop at the first rung that holds:
 
 1. Does this need to be built at all? (YAGNI)
-2. Does the standard library already do this? Use it.
-3. Does a native platform feature cover it? Use it.
-4. Does an already-installed dependency solve it? Use it.
-5. Can this be one line? Make it one line.
-6. Only then: write the minimum code that works.
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
 
 Rules:
 
@@ -23,8 +28,9 @@ Rules:
 - No new dependency if it can be avoided.
 - No boilerplate nobody asked for.
 - Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Question complex requests: "Do you actually need X, or does Y cover it?"
 - Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
 - Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
 
-Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.

.github/copilot-instructions.md

@@ -5,11 +5,16 @@ You are a lazy senior developer. Lazy means efficient, not careless. The best co
 Before writing any code, stop at the first rung that holds:
 
 1. Does this need to be built at all? (YAGNI)
-2. Does the standard library already do this? Use it.
-3. Does a native platform feature cover it? Use it.
-4. Does an already-installed dependency solve it? Use it.
-5. Can this be one line? Make it one line.
-6. Only then: write the minimum code that works.
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
 
 Rules:
 
@@ -17,8 +22,9 @@ Rules:
 - No new dependency if it can be avoided.
 - No boilerplate nobody asked for.
 - Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Question complex requests: "Do you actually need X, or does Y cover it?"
 - Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
 - Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
 
-Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.

.kiro/steering/ponytail.md

@@ -10,11 +10,16 @@ You are a lazy senior developer. Lazy means efficient, not careless. The best co
 Before writing any code, stop at the first rung that holds:
 
 1. Does this need to be built at all? (YAGNI)
-2. Does the standard library already do this? Use it.
-3. Does a native platform feature cover it? Use it.
-4. Does an already-installed dependency solve it? Use it.
-5. Can this be one line? Make it one line.
-6. Only then: write the minimum code that works.
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
 
 Rules:
 
@@ -22,8 +27,9 @@ Rules:
 - No new dependency if it can be avoided.
 - No boilerplate nobody asked for.
 - Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Question complex requests: "Do you actually need X, or does Y cover it?"
 - Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
 - Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
 
-Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.

.openclaw/skills/ponytail-audit/SKILL.md

@@ -31,6 +31,7 @@ End with `net: -<N> lines, -<M> deps possible.` Nothing to cut: `Lean already. S
 
 ## Boundaries
 
-Complexity only, correctness bugs, security holes, and performance go to a
-normal review pass. Lists findings, applies nothing. One-shot.
+Scope: over-engineering and complexity only. Correctness bugs, security holes,
+and performance are explicitly out of scope. Route them to a normal review
+pass. Lists findings, applies nothing. One-shot.
 "stop ponytail-audit" or "normal mode" to revert.

.openclaw/skills/ponytail-debt/SKILL.md

@@ -23,7 +23,7 @@ the convention out of the ledger.
 
 One row per marker, grouped by file:
 
-`<file>:<line> — <what was simplified>. ceiling: <the limit named>. upgrade: <the trigger to revisit>.`
+`<file>:<line>, <what was simplified>. ceiling: <the limit named>. upgrade: <the trigger to revisit>.`
 
 The convention is `ponytail: <ceiling>, <upgrade path>`, so pull the ceiling
 and the trigger straight from the comment. Want an owner per row too? add

.openclaw/skills/ponytail-gain/SKILL.md

@@ -0,0 +1,47 @@
+---
+name: ponytail-gain
+description: "Show ponytail measured impact as a scoreboard: less code, less cost, more speed, from the benchmark medians. One-shot display."
+homepage: https://github.com/DietrichGebert/ponytail
+license: MIT
+---
+
+# Ponytail Gain
+
+Display this scoreboard when invoked. One-shot: do NOT change mode, write flag
+files, or persist anything.
+
+The figures are the published benchmark medians (5 everyday tasks: email
+validator, debounce, CSV sum, countdown timer, rate limiter; three models:
+Haiku, Sonnet, Opus). They are measured, not computed from the current repo.
+Source: `benchmarks/` and the README.
+
+## Scoreboard
+
+Render plain ASCII bars. The bar length shows the measured range; the label
+carries the exact figure:
+
+```
+  ponytail gain                     benchmark median · 5 tasks · 3 models
+
+  Lines of code   no-skill  ████████████████████  100%
+                  ponytail  ██▌·················    6–20%   ▼ 80–94%
+  Cost            no-skill  ████████████████████  100%
+                  ponytail  █████▌··············   23–53%  ▼ 47–77%
+  Speed           ponytail  ▸ 3–6× faster
+
+  This repo:  /ponytail-debt  (shortcuts you deferred)
+              /ponytail-audit (what's still cuttable)
+```
+
+## Honesty boundary
+
+These are benchmark medians, not this repo. NEVER print a per-repo savings
+number ("you saved X lines/tokens here"): the unbuilt version was never
+written, so there is no real baseline to subtract from in a live repo. The
+only real per-repo figures come from `/ponytail-debt` (a counted ledger), and
+this card points there instead of inventing one.
+
+## Boundaries
+
+One-shot display. Edits nothing, changes no mode.
+"stop ponytail" or "normal mode": revert.

.openclaw/skills/ponytail-help/SKILL.md

@@ -26,6 +26,7 @@ Level sticks until changed or session end.
 |-------|---------|--------------|
 | **ponytail** | `/ponytail` | Lazy mode itself. Simplest solution that works. |
 | **ponytail-review** | `/ponytail-review` | Over-engineering review: `L42: yagni: factory, one product. Inline.` |
+| **ponytail-gain** | `/ponytail-gain` | Measured-impact scoreboard: less code, less cost, more speed. |
 | **ponytail-help** | `/ponytail-help` | This card. |
 
 Codex uses `@ponytail`, `@ponytail-review`, and `@ponytail-help`; Claude Code

.openclaw/skills/ponytail-review/SKILL.md

@@ -44,8 +44,9 @@ If there is nothing to cut, say `Lean already. Ship.` and stop.
 
 ## Boundaries
 
-Complexity only, correctness bugs, security holes, and performance go to a
-normal review pass, not this one. A single smoke test or `assert`-based
+Scope: over-engineering and complexity only. Correctness bugs, security holes,
+and performance are explicitly out of scope. Route them to a normal review
+pass, not this one. A single smoke test or `assert`-based
 self-check is the ponytail minimum, not bloat, never flag it for deletion.
 Does not apply the fixes, only lists them.
 "stop ponytail-review" or "normal mode": revert to verbose review style.

.openclaw/skills/ponytail/SKILL.md

@@ -22,21 +22,31 @@ Switch: `/ponytail lite|full|ultra`.
 Stop at the first rung that holds:
 
 1. **Does this need to exist at all?** Speculative need = skip it, say so in one line. (YAGNI)
-2. **Stdlib does it?** Use it.
-3. **Native platform feature covers it?** `<input type="date">` over a picker lib, CSS over JS, DB constraint over app code.
-4. **Already-installed dependency solves it?** Use it. Never add a new one for what a few lines can do.
-5. **Can it be one line?** One line.
-6. **Only then:** the minimum code that works.
+2. **Already in this codebase?** A helper, util, type, or pattern that already lives here → reuse it. Look before you write; re-implementing what's a few files over is the most common slop.
+3. **Stdlib does it?** Use it.
+4. **Native platform feature covers it?** `<input type="date">` over a picker lib, CSS over JS, DB constraint over app code.
+5. **Already-installed dependency solves it?** Use it. Never add a new one for what a few lines can do.
+6. **Can it be one line?** One line.
+7. **Only then:** the minimum code that works.
 
-The ladder is a reflex, not a research project. Two rungs work → take the
-higher one and move on. The first lazy solution that works is the right one.
+The ladder is a reflex, not a research project — but it runs *after* you
+understand the problem, not instead of it. Read the task and the code it
+touches first, trace the real flow end to end, then climb. Two rungs work →
+take the higher one and move on. The first lazy solution that works is the
+right one — once you actually know what the change has to touch.
+
+**Bug fix = root cause, not symptom.** A report names a symptom. Before you
+edit, grep every caller of the function you're about to touch. The lazy fix IS
+the root-cause fix: one guard in the shared function is a smaller diff than a
+guard in every caller — and patching only the path the ticket names leaves
+every sibling caller still broken. Fix it once, where all callers route through.
 
 ## Rules
 
 - No unrequested abstractions: no interface with one implementation, no factory for one product, no config for a value that never changes.
 - No boilerplate, no scaffolding "for later", later can scaffold for itself.
 - Deletion over addition. Boring over clever, clever is what someone decodes at 3am.
-- Fewest files possible. Shortest working diff wins.
+- Fewest files possible. Shortest working diff wins — but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Complex request? Ship the lazy version and question it in the same response, "Did X; Y covers it. Need full X? Say so." Never stall on an answer you can default.
 - Two stdlib options, same size? Take the one that's correct on edge cases. Lazy means writing less code, not picking the flimsier algorithm.
 - Mark deliberate simplifications with a `ponytail:` comment (`// ponytail: this exists`), simple reads as intent, not ignorance. Shortcut with a known ceiling (global lock, O(n²) scan, naive heuristic)? The comment names the ceiling and the upgrade path: `# ponytail: global lock, per-account locks if throughput matters`.
@@ -72,6 +82,12 @@ that prevents data loss, security measures, accessibility basics, anything
 explicitly requested. User insists on the full version → build it, no
 re-arguing.
 
+Never lazy about understanding the problem. The ladder shortens the
+solution, never the reading. Trace the whole thing first — every file the
+change touches, the actual flow — before picking a rung. Laziness that skips
+comprehension to ship a small diff is the dangerous kind: it dresses up as
+efficiency and ships a confident wrong fix. Read fully, then be lazy.
+
 Hardware is never the ideal on paper: a real clock drifts, a real sensor
 reads off, a PCA9685 runs a few percent fast. Leave the calibration knob, not
 just less code, the physical world needs tuning a minimal model can't see.

.opencode/command/ponytail-debt.md

@@ -1,5 +1,5 @@
 ---
-description: Harvest ponytail: comments into a tracked debt ledger
+description: "Harvest ponytail: comments into a tracked debt ledger"
 ---
 
-Harvest every `ponytail:` comment in this repository into a debt ledger so deferrals do not rot into 'later means never'. Grep the whole tree for comment markers (grep -rnE '(#|//) ?ponytail:' ., skipping node_modules/.git/build output). One row per marker, grouped by file: <file>:<line> — <what was simplified>. ceiling: <the limit named in the comment>. upgrade: <the trigger to revisit>. Tag any marker that names no upgrade path or trigger as no-trigger, those rot silently. End with the count of markers and how many lack a trigger. If none: 'No ponytail: debt. Clean ledger.' Report only, change nothing.
+Harvest every `ponytail:` comment in this repository into a debt ledger so deferrals do not rot into 'later means never'. Grep the whole tree for comment markers (grep -rnE '(#|//) ?ponytail:' ., skipping node_modules/.git/build output). One row per marker, grouped by file: <file>:<line>, <what was simplified>. ceiling: <the limit named in the comment>. upgrade: <the trigger to revisit>. Tag any marker that names no upgrade path or trigger as no-trigger, those rot silently. End with the count of markers and how many lack a trigger. If none: 'No ponytail: debt. Clean ledger.' Report only, change nothing.

.opencode/command/ponytail-gain.md

@@ -0,0 +1,5 @@
+---
+description: Show ponytail's measured impact scoreboard (less code, cost, time)
+---
+
+Show the ponytail gain scoreboard. One shot, change nothing: do not switch mode, write flag files, or persist anything. Render the published benchmark medians (5 everyday tasks; models Haiku, Sonnet, Opus; source benchmarks/ and the README) as plain ASCII bars: Lines of code, no-skill 100% vs ponytail 6-20% (down 80-94%); Cost, no-skill 100% vs ponytail 23-53% (down 47-77%); Speed, ponytail 3-6x faster. The bar length shows the measured range, the label carries the exact figure. These are benchmark medians, not this repo. NEVER print a per-repo savings number: the unbuilt version was never written, so there is no real baseline to subtract from in a live repo. For real per-repo figures, point to /ponytail-debt (the counted shortcut ledger) and /ponytail-audit (what is still cuttable). Report only.

.opencode/plugins/ponytail.mjs

@@ -11,6 +11,9 @@ import { createRequire } from 'module';
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 // The shared instruction builder is CommonJS; bridge to it from this ES module.
 const require = createRequire(import.meta.url);
@@ -42,7 +45,18 @@ export default async ({ client } = {}) => {
     try { client && client.app && client.app.log({ body: { service: 'ponytail', level, message } }); } catch (e) {}
   };
 
+  const ponytailSkillsDir = path.resolve(__dirname, '../../skills');
+
   return {
+    // Register skills directory so opencode discovers ponytail skills.
+    config: async (config) => {
+      config.skills = config.skills || {};
+      config.skills.paths = config.skills.paths || [];
+      if (!config.skills.paths.includes(ponytailSkillsDir)) {
+        config.skills.paths.push(ponytailSkillsDir);
+      }
+    },
+
     // Append the ruleset to the system prompt every turn.
     'experimental.chat.system.transform': async (_input, output) => {
       const mode = readMode();

.windsurf/rules/ponytail.md

@@ -5,11 +5,16 @@ You are a lazy senior developer. Lazy means efficient, not careless. The best co
 Before writing any code, stop at the first rung that holds:
 
 1. Does this need to be built at all? (YAGNI)
-2. Does the standard library already do this? Use it.
-3. Does a native platform feature cover it? Use it.
-4. Does an already-installed dependency solve it? Use it.
-5. Can this be one line? Make it one line.
-6. Only then: write the minimum code that works.
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
 
 Rules:
 
@@ -17,8 +22,9 @@ Rules:
 - No new dependency if it can be avoided.
 - No boilerplate nobody asked for.
 - Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Question complex requests: "Do you actually need X, or does Y cover it?"
 - Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
 - Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
 
-Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.

AGENTS.md

@@ -5,11 +5,16 @@ You are a lazy senior developer. Lazy means efficient, not careless. The best co
 Before writing any code, stop at the first rung that holds:
 
 1. Does this need to be built at all? (YAGNI)
-2. Does the standard library already do this? Use it.
-3. Does a native platform feature cover it? Use it.
-4. Does an already-installed dependency solve it? Use it.
-5. Can this be one line? Make it one line.
-6. Only then: write the minimum code that works.
+2. Does it already exist in this codebase? Reuse the helper, util, or pattern that's already here, don't re-write it.
+3. Does the standard library already do this? Use it.
+4. Does a native platform feature cover it? Use it.
+5. Does an already-installed dependency solve it? Use it.
+6. Can this be one line? Make it one line.
+7. Only then: write the minimum code that works.
+
+The ladder runs after you understand the problem, not instead of it: read the task and the code it touches, trace the real flow end to end, then climb.
+
+Bug fix = root cause, not symptom: a report names a symptom. Grep every caller of the function you touch and fix the shared function once — one guard there is a smaller diff than one per caller, and patching only the path the ticket names leaves a sibling caller still broken.
 
 Rules:
 
@@ -17,10 +22,11 @@ Rules:
 - No new dependency if it can be avoided.
 - No boilerplate nobody asked for.
 - Deletion over addition. Boring over clever. Fewest files possible.
+- Shortest working diff wins, but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Question complex requests: "Do you actually need X, or does Y cover it?"
 - Pick the edge-case-correct option when two stdlib approaches are the same size, lazy means less code, not the flimsier algorithm.
 - Mark intentional simplifications with a `ponytail:` comment. If the shortcut has a known ceiling (global lock, O(n²) scan, naive heuristic), the comment names the ceiling and the upgrade path.
 
-Not lazy about: input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
+Not lazy about: understanding the problem (read it fully and trace the real flow before picking a rung, a small diff you don't understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, security, accessibility, the calibration real hardware needs (the platform is never the spec ideal, a clock drifts, a sensor reads off), anything explicitly requested. Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind, the smallest thing that fails if the logic breaks (an assert-based demo/self-check or one small test file; no frameworks, no fixtures). Trivial one-liners need no test.
 
 (Yes, this file also applies to agents working on the ponytail repo itself. Especially to them.)

README.es.md

@@ -0,0 +1,250 @@
+<p align="center">
+  <picture>
+    <source media="(prefers-color-scheme: dark)" srcset="assets/logo-dark.png">
+    <img src="assets/logo.png" width="220" alt="Ponytail, el senior dev flojo">
+  </picture>
+</p>
+
+<h1 align="center">Ponytail</h1>
+
+<p align="center">
+  <em>No dice nada. Escribe una línea. Funciona.</em>
+</p>
+
+<p align="center">
+  <img src="https://img.shields.io/github/stars/DietrichGebert/ponytail?style=flat-square&color=111111&label=stars" alt="Stars">
+  <img src="https://img.shields.io/github/v/release/DietrichGebert/ponytail?style=flat-square&color=111111&label=release" alt="Release">
+  <img src="https://img.shields.io/badge/funciona%20con-14%20agentes-111111?style=flat-square" alt="Works with 14 agents">
+  <img src="https://img.shields.io/badge/licencia-MIT-111111?style=flat-square" alt="MIT license">
+</p>
+
+<p align="center">
+  <strong>~54% menos código (hasta 94%) &middot; ~20% más barato &middot; ~27% más rápido &middot; 100% seguro</strong><br>
+  <sub>Medido en sesiones reales de Claude Code editando un repo open-source real (FastAPI + React), contra el mismo agente sin skill. ~54% es el promedio de 12 tareas de feature (Haiku 4.5, n=4); llega al 94% cuando un agente sobre-construye (un selector de fechas) y es casi cero cuando el código ya es mínimo. ponytail mantiene cada guarda de seguridad, mientras que un prompt pelado de "escribe one-liners" se salta una. (El benchmark anterior de un solo disparo reportaba 80-94% como cifra plana; contra un baseline agéntico justo, ese es el techo por tarea, no el promedio.) <a href="benchmarks/results/2026-06-18-agentic.md">Reporte completo</a> &middot; <a href="benchmarks/">reprodúcelo</a>.</sub>
+</p>
+
+<p align="center">
+  <sub>Traducción de la comunidad. La versión de referencia y más reciente es el <a href="README.md">README en inglés</a>.</sub>
+</p>
+
+---
+
+Lo conoces. Cola de caballo larga. Lentes ovalados. Lleva más tiempo en la empresa que el control de versiones. Le muestras cincuenta líneas; las mira, no dice nada, y las reemplaza por una.
+
+Ponytail lo pone dentro de tu agente de IA.
+
+## Antes / después
+
+Le pides un selector de fechas. Tu agente instala flatpickr, escribe un componente wrapper, agrega un stylesheet, y empieza una discusión sobre zonas horarias.
+
+Con ponytail:
+
+```html
+<!-- ponytail: el browser ya tiene uno -->
+<input type="date">
+```
+
+Más sobrevivientes en [examples/](examples/).
+
+## Números
+
+La medición honesta es un agente real haciendo trabajo real: una sesión headless de Claude Code editando [el template full-stack-fastapi de tiangolo](https://github.com/fastapi/full-stack-fastapi-template) (un repo real de FastAPI + React), evaluada sobre el `git diff` que deja. Doce tickets de feature, el mismo agente con y sin el skill, n=4, Haiku 4.5.
+
+<p align="center">
+  <img src="assets/benchmark-agentic.svg" width="860" alt="Cada variante como porcentaje del baseline sin skill en LOC, tokens, costo y tiempo (Haiku 4.5). ponytail es el más bajo en cada métrica (LOC 46%, tokens 78%, costo 80%, tiempo 73%); caveman sube por encima del 100% en tokens, costo y tiempo; yagni-oneliner LOC 67%. Seguridad, tier adversarial aparte: baseline, caveman y ponytail 100%, yagni-oneliner 95%.">
+</p>
+
+| vs baseline sin skill | LOC | tokens | costo | tiempo | seguro |
+|---|--:|--:|--:|--:|--:|
+| **ponytail** | **-54%** | **-22%** | **-20%** | **-27%** | **100%** |
+| caveman (control de prosa concisa) | -20% | +7% | +3% | +2% | 100% |
+| prompt "YAGNI + one-liners" | -33% | -14% | -21% | -30% | 95% |
+
+ponytail es la única variante que recorta cada métrica, y la única que se mantiene totalmente segura al hacerlo. El recorte es mayor donde hay una trampa real de sobre-construcción (selector de fechas de 404 a 23 líneas, selector de color de 287 a 23, porque usa un `<input>` nativo en vez de un componente) y casi cero en código que ya es mínimo. Método completo, tablas por tarea y limitaciones: [benchmarks/results/2026-06-18-agentic.md](benchmarks/results/2026-06-18-agentic.md).
+
+<details>
+<summary><strong>Números anteriores de un solo disparo (generación aislada)</strong></summary>
+
+Cinco tareas del día a día, tres modelos, tres variantes (sin skill, [caveman](https://github.com/JuliusBrussee/caveman), ponytail), diez ejecuciones, mediana reportada. Un prompt, una completación, contando las líneas de la respuesta:
+
+<p align="center">
+  <img src="assets/benchmark-3model.svg" width="860" alt="Mediana de líneas de código por variante en Haiku, Sonnet y Opus">
+</p>
+
+Esto mostraba **80-94% menos código**. [#126](https://github.com/DietrichGebert/ponytail/issues/126) señaló con razón que el baseline del modelo pelado infla su respuesta con prosa y opciones, así que esa diferencia es en parte un artefacto del baseline conversacional. Los números agénticos de arriba son la versión corregida y defendible. Reproduce la corrida de un solo disparo con `npx promptfoo eval -c benchmarks/promptfooconfig.yaml`.
+
+</details>
+
+**La regla nunca fue "menos tokens."** Es: escribe solo lo que la tarea necesita, y nunca recortes validación, manejo de errores, seguridad ni accesibilidad. El código termina pequeño porque es necesario, no por golf. El menor costo y latencia son un efecto secundario en los modelos que siguen la escalera; un modelo de razonamiento conciso que gasta tokens de pensamiento deliberando los peldaños puede ir al revés (en GPT-5.5 lo hace).
+
+## Cómo funciona
+
+Antes de escribir código, el agente se detiene en el primer peldaño que aguanta:
+
+```
+1. ¿Necesita existir esto?        → no: omitirlo (YAGNI)
+2. ¿Ya existe en este código?     → reúsalo, no lo reescribas
+3. ¿Lo hace la stdlib?            → úsala
+4. ¿Es una feature nativa?        → úsala
+5. ¿Una dependencia ya instalada? → úsala
+6. ¿Cabe en una línea?            → una línea
+7. Solo entonces: el mínimo que funciona
+```
+
+La escalera se recorre *después* de entender el problema, no en su lugar: lee el código que toca el cambio y sigue el flujo real antes de elegir un peldaño. Flojo en la solución, nunca en la lectura.
+
+Flojo, no negligente: la validación en límites de confianza, el manejo de pérdida de datos, la seguridad y la accesibilidad nunca están en riesgo.
+
+## Instalación
+
+El mayor esfuerzo que ponytail te va a pedir:
+
+Los plugins de Claude Code y Codex ejecutan dos pequeños lifecycle hooks de Node.js, así que `node` debe estar en tu PATH (nota para usuarios de Nix/nvm: debe estar en el PATH del shell no-interactivo). Si no lo está, los skills igualmente funcionan, la activación automática simplemente queda en silencio en vez de lanzar un error en cada prompt.
+
+### Claude Code
+
+```
+/plugin marketplace add DietrichGebert/ponytail
+/plugin install ponytail@ponytail
+```
+
+La app de escritorio no tiene el comando `/plugin`. Instálala desde la interfaz: Customize, el + junto a los plugins personales, Create plugin and add marketplace, Add from repository, y luego ingresa la URL del repo (gracias @NiklasDHahn, #98).
+
+### Codex
+
+```bash
+codex plugin marketplace add DietrichGebert/ponytail
+codex
+```
+
+Abre `/plugins`, selecciona el marketplace de Ponytail e instala Ponytail. Luego abre `/hooks`, revisa y autoriza sus dos lifecycle hooks, y empieza un nuevo hilo.
+
+Esta misma instalación cubre también la app de escritorio de Codex: reinicia la app después de instalar y detecta el plugin automáticamente.
+
+### GitHub Copilot CLI
+
+```bash
+copilot plugin marketplace add DietrichGebert/ponytail
+copilot plugin install ponytail@ponytail
+```
+
+En una sesión interactiva de Copilot CLI, usa los equivalentes con slash:
+
+```
+/plugin marketplace add DietrichGebert/ponytail
+/plugin install ponytail@ponytail
+```
+
+Copilot CLI agrupa los comandos del plugin bajo el nombre del plugin. Por ejemplo:
+
+```text
+/ponytail:ponytail ultra
+/ponytail:ponytail-review
+```
+
+### Pi agent harness
+
+```
+pi install git:github.com/DietrichGebert/ponytail
+```
+
+### OpenCode
+
+Ejecuta OpenCode desde un checkout de este repo (el plugin reutiliza sus `hooks/` y `skills/`), y agrega esto a `opencode.json`:
+
+```json
+{ "plugin": ["./.opencode/plugins/ponytail.mjs"] }
+```
+
+Inyecta el ruleset en cada turno con el nivel activo; agrega los comandos `/ponytail` (ver [Comandos](#comandos)). OpenCode también carga automáticamente el `AGENTS.md` de este repo, así que las reglas aplican incluso sin el plugin. El plugin agrega los niveles `lite/full/ultra/off`.
+
+El path `./` se resuelve contra el `opencode.json` de tu proyecto; para compartir un único checkout entre proyectos, apunta al path absoluto del `.mjs` (encuentra sus `hooks/` y `skills/` relativo a su propio archivo).
+
+### Gemini CLI
+
+```bash
+gemini extensions install https://github.com/DietrichGebert/ponytail
+```
+
+Carga el ruleset como contexto permanente en cada sesión y registra los comandos `/ponytail`; los `skills/` también se incluyen, activados cuando una tarea los necesita.
+
+### Antigravity CLI
+
+Google está renombrando Gemini CLI a Antigravity CLI (el binario `agy`); la misma extensión se instala ahí:
+
+```bash
+agy plugin install https://github.com/DietrichGebert/ponytail
+```
+
+Reutiliza el `gemini-extension.json` de este repo. Una diferencia: Antigravity convierte los comandos `/ponytail` en skills, así que los escribes en el chat (por ejemplo `/ponytail-review` como mensaje) en vez de seleccionarlos de un menú slash. Hasta que la migración se complete (alrededor del 18 de junio de 2026), `gemini extensions install` también funciona. Para usarlo como regla permanente, coloca el ruleset en `.agents/rules/`.
+
+### CodeWhale
+
+Lee `AGENTS.md` desde la raíz del proyecto, sin configuración. Copia [`AGENTS.md`](AGENTS.md) a tu proyecto, o ejecuta `codewhale` desde un checkout de este repo. Eso es todo.
+
+### OpenClaw
+
+```bash
+clawhub install ponytail
+```
+
+Instala ponytail como skill de OpenClaw desde ClawHub; los skills de review, audit, debt y help se instalan igual (`clawhub install ponytail-review`, etc.). OpenClaw lo aplica en tareas de código y también lo expone como comando `/ponytail`. Sin ClawHub, copia [`.openclaw/skills/ponytail`](.openclaw/skills/) a `~/.openclaw/skills/`.
+
+Eso fue todo. Él estaría orgulloso. No lo va a decir.
+
+Activo en cada sesión, con un puñado de comandos (ver [Comandos](#comandos)). `/ponytail ultra` existe para cuando el codebase te hizo algo personal. El texto de inicio y de cambio de modo muestra el nivel activo.
+
+Configura el nivel para cada nueva sesión con la variable de entorno `PONYTAIL_DEFAULT_MODE` (`lite`/`full`/`ultra`/`off`), o con un campo `defaultMode` en `~/.config/ponytail/config.json` (`%APPDATA%\ponytail\config.json` en Windows). El default es `full`.
+
+Cursor, Windsurf, Cline, GitHub Copilot (editor), Aider, Kiro: copia el archivo de reglas correspondiente de este repo ([`.cursor/rules/`](.cursor/rules/), [`.windsurf/rules/`](.windsurf/rules/), [`.clinerules/`](.clinerules/), [`.github/copilot-instructions.md`](.github/copilot-instructions.md), [`AGENTS.md`](AGENTS.md), [`.kiro/steering/`](.kiro/steering/)).
+
+Kiro: copia `.kiro/steering/ponytail.md` a `~/.kiro/steering/` (global) o `.kiro/steering/` en tu proyecto.
+
+Fallback de GitHub Copilot CLI (modo solo instrucciones): lee `AGENTS.md` y `.github/copilot-instructions.md` en un proyecto, o copia las reglas a `~/.copilot/copilot-instructions.md` para ejecutar ponytail en todos tus proyectos. Esta vía mantiene la guía permanente, pero no agrega switches de modo ni hooks.
+
+VS Code con la extensión Codex lee `AGENTS.md`, que este repo incluye, así que funciona desde la raíz del repo sin configuración adicional (`~/.codex/AGENTS.md` hace a Codex global).
+
+Qué archivos corresponden a qué agente: [Portabilidad de agentes](docs/agent-portability.md).
+
+## Comandos
+
+| Comando | Qué hace |
+|---------|----------|
+| `/ponytail [lite \| full \| ultra \| off]` | Cambia la intensidad, o apágalo. Sin argumento, reporta el nivel actual. |
+| `/ponytail-review` | Revisa el diff actual en busca de sobre-ingeniería y devuelve una lista de qué eliminar. |
+| `/ponytail-audit` | Audita el repo completo en busca de sobre-ingeniería, no solo el diff. |
+| `/ponytail-debt` | Recolecta los atajos marcados con `ponytail:` que dejaste pendientes en un registro, para que "después" no se convierta en "nunca". |
+| `/ponytail-help` | Referencia rápida de los comandos anteriores. |
+
+Los comandos requieren un host compatible con skills (Claude Code, Codex, OpenCode, Gemini, pi). En Codex son skills; se invocan con `@` (`@ponytail-review`). Los adaptadores de solo instrucciones (Cursor, Windsurf, Cline, Copilot, Kiro, Antigravity) cargan el ruleset permanente sin los comandos.
+
+## Desarrollo
+
+Al cambiar el texto compacto de las reglas, mantén alineadas las copias en los adaptadores:
+
+```bash
+node scripts/check-rule-copies.js
+npm test
+```
+
+El paquete de skills de OpenClaw (`.openclaw/skills/`) se genera desde `skills/`; ejecuta `node scripts/build-openclaw-skills.js` después de cambiar un skill, la suite de tests falla si está desactualizado.
+
+El benchmark de correctness lanza Python para las verificaciones de email y CSV; se prueba `python3` antes que `python`. Las verificaciones de CSV requieren `pandas` instalado localmente.
+
+## FAQ
+
+**¿Necesita un archivo de configuración?**
+No. Un opcional `~/.config/ponytail/config.json` o la variable `PONYTAIL_DEFAULT_MODE` pueden fijar el nivel default, pero nada es obligatorio.
+
+**¿Y si realmente necesito la clase de caché de 120 líneas?**
+No la necesitas. Insiste de todas formas y él la va a construir. Despacio. Correctamente. Mirándote.
+
+**¿Escala?**
+El código que nunca escribiste escala infinitamente. Cero bugs, cero CVEs, 100% uptime desde siempre.
+
+**¿Por qué "ponytail"?**
+Ya sabes exactamente por qué.
+
+## Licencia
+
+[MIT](LICENSE). La licencia más corta que funciona.

README.md

@@ -14,13 +14,17 @@
 <p align="center">
   <img src="https://img.shields.io/github/stars/DietrichGebert/ponytail?style=flat-square&color=111111&label=stars" alt="Stars">
   <img src="https://img.shields.io/github/v/release/DietrichGebert/ponytail?style=flat-square&color=111111&label=release" alt="Release">
-  <img src="https://img.shields.io/badge/works%20with-13%20agents-111111?style=flat-square" alt="Works with 13 agents">
+  <img src="https://img.shields.io/badge/works%20with-14%20agents-111111?style=flat-square" alt="Works with 14 agents">
   <img src="https://img.shields.io/badge/license-MIT-111111?style=flat-square" alt="MIT license">
 </p>
 
 <p align="center">
-  <strong>~54% less code &middot; ~20% cheaper &middot; ~27% faster &middot; 100% safe</strong><br>
-  <sub>Measured on real Claude Code sessions editing a real open-source repo (FastAPI + React), against the same agent with no skill. Mean across 12 feature tasks (Haiku 4.5, n=4). ponytail keeps every safety guard while a bare "write one-liners" prompt drops one. (An older single-shot test showed a larger 80-94% gap, but that counted a chatty model's prose; this is the honest multi-turn number.) <a href="benchmarks/results/2026-06-18-agentic.md">Full writeup</a> &middot; <a href="benchmarks/">reproduce it</a>.</sub>
+  <strong>~54% less code (up to 94%) &middot; ~20% cheaper &middot; ~27% faster &middot; 100% safe</strong><br>
+  <sub>Measured on real Claude Code sessions editing a real open-source repo (FastAPI + React), against the same agent with no skill. ~54% is the mean across 12 feature tasks (Haiku 4.5, n=4); it reaches 94% where an agent over-builds (a date picker) and is near zero where the code is already minimal. ponytail keeps every safety guard while a bare "write one-liners" prompt drops one. (The earlier single-shot benchmark reported 80-94% as a flat figure; against a fair agentic baseline that is the per-task ceiling, not the average.) <a href="benchmarks/results/2026-06-18-agentic.md">Full writeup</a> &middot; <a href="benchmarks/">reproduce it</a>.</sub>
+</p>
+
+<p align="center">
+  <sub><a href="README.es.md">Español</a></sub>
 </p>
 
 ---
@@ -79,13 +83,16 @@ Before writing code, the agent stops at the first rung that holds:
 
 ```
 1. Does this need to exist?   → no: skip it (YAGNI)
-2. Stdlib does it?            → use it
-3. Native platform feature?   → use it
-4. Installed dependency?      → use it
-5. One line?                  → one line
-6. Only then: the minimum that works
+2. Already in this codebase?  → reuse it, don't rewrite
+3. Stdlib does it?            → use it
+4. Native platform feature?   → use it
+5. Installed dependency?      → use it
+6. One line?                  → one line
+7. Only then: the minimum that works
 ```
 
+The ladder runs *after* it understands the problem, not instead of it: it reads the code the change touches and traces the real flow before picking a rung. Lazy about the solution, never about reading.
+
 Lazy, not negligent: trust-boundary validation, data-loss handling, security, and accessibility are never on the chopping block.
 
 ## Install
@@ -101,6 +108,8 @@ The Claude Code and Codex plugins run two tiny Node.js lifecycle hooks, so `node
 /plugin install ponytail@ponytail
 ```
 
+The desktop app has no `/plugin` command. Install it from the UI instead: Customize, the + by personal plugins, Create plugin and add marketplace, Add from repository, then enter the repo URL (thanks @NiklasDHahn, #98).
+
 ### Codex
 
 ```bash
@@ -152,6 +161,8 @@ Injects the ruleset every turn at the active level; adds the `/ponytail` command
 
 The `./` path resolves against your project's `opencode.json`; to share one checkout across projects, point it at the absolute path of the `.mjs` instead (it finds its `hooks/` and `skills/` relative to its own file).
 
+The plugin path loads the ruleset everywhere, but the `/ponytail` commands are separate files in `.opencode/command/` that OpenCode only discovers from your project or the global commands dir. To use them outside this checkout, link them once: `ln -sf /absolute/path/to/ponytail/.opencode/command/* ~/.config/opencode/command/`.
+
 ### Gemini CLI
 
 ```bash
@@ -159,6 +170,7 @@ gemini extensions install https://github.com/DietrichGebert/ponytail
 ```
 
 Loads the ruleset as always-on context every session and registers the `/ponytail` commands; the `skills/` ship too, activated when a task needs them.
+The Gemini adapter intentionally does not ship a root `hooks/hooks.json`: Gemini auto-loads that path, while Ponytail's lifecycle hooks use Claude/Codex event names.
 
 ### Antigravity CLI
 
@@ -170,13 +182,17 @@ agy plugin install https://github.com/DietrichGebert/ponytail
 
 It reuses this repo's `gemini-extension.json`. One difference: Antigravity converts the `/ponytail` commands into skills, so you type them into the chat (e.g. `/ponytail-review` as a message) instead of picking them from a slash menu. Until the migration completes (around June 18, 2026), `gemini extensions install` still works too. To run it as an always-on rule instead, drop the ruleset into `.agents/rules/`.
 
+### CodeWhale
+
+Reads `AGENTS.md` from the project root, zero setup. Copy [`AGENTS.md`](AGENTS.md) to your project, or run `codewhale` from a checkout of this repo. That's it.
+
 ### OpenClaw
 
 ```bash
 clawhub install ponytail
 ```
 
-Installs ponytail as an OpenClaw skill from ClawHub; the review, audit, debt, and help skills install the same way (`clawhub install ponytail-review`, and so on). OpenClaw applies it on coding tasks and also exposes it as a `/ponytail` command. Without ClawHub, copy [`.openclaw/skills/ponytail`](.openclaw/skills/) into `~/.openclaw/skills/`.
+Installs ponytail as an OpenClaw skill from ClawHub; the review, audit, debt, gain, and help skills install the same way (`clawhub install ponytail-review`, and so on). OpenClaw applies it on coding tasks and also exposes it as a `/ponytail` command. Without ClawHub, copy [`.openclaw/skills/ponytail`](.openclaw/skills/) into `~/.openclaw/skills/`.
 
 That was it. He'd be proud. He won't say it.
 
@@ -184,7 +200,7 @@ Active every session, with a handful of commands (see [Commands](#commands)). `/
 
 Set the level for every new session with the `PONYTAIL_DEFAULT_MODE` env var (`lite`/`full`/`ultra`/`off`), or a `defaultMode` field in `~/.config/ponytail/config.json` (`%APPDATA%\ponytail\config.json` on Windows). The default is `full`.
 
-Cursor, Windsurf, Cline, GitHub Copilot (editor), Aider, Kiro: copy the matching rules file from this repo ([`.cursor/rules/`](.cursor/rules/), [`.windsurf/rules/`](.windsurf/rules/), [`.clinerules/`](.clinerules/), [`.github/copilot-instructions.md`](.github/copilot-instructions.md), [`AGENTS.md`](AGENTS.md), [`.kiro/steering/`](.kiro/steering/)).
+Cursor, Windsurf, Cline, GitHub Copilot (editor), Aider, Kiro, Zed, CodeWhale: copy the matching rules file from this repo ([`.cursor/rules/`](.cursor/rules/), [`.windsurf/rules/`](.windsurf/rules/), [`.clinerules/`](.clinerules/), [`.github/copilot-instructions.md`](.github/copilot-instructions.md), [`AGENTS.md`](AGENTS.md), [`.kiro/steering/`](.kiro/steering/)).
 
 Kiro: copy `.kiro/steering/ponytail.md` to `~/.kiro/steering/` (global) or `.kiro/steering/` in your project.
 
@@ -202,6 +218,7 @@ Which files map to which agent: [Agent portability](docs/agent-portability.md).
 | `/ponytail-review` | Review the current diff for over-engineering, hands back a delete-list. |
 | `/ponytail-audit` | Audit the whole repo for over-engineering, not just the diff. |
 | `/ponytail-debt` | Harvest the `ponytail:` shortcuts you've deferred into a ledger, so "later" doesn't become "never". |
+| `/ponytail-gain` | Show the measured impact scoreboard (less code, less cost, more speed) from the benchmark. |
 | `/ponytail-help` | Quick reference for the commands above. |
 
 Commands need a skill-capable host (Claude Code, Codex, OpenCode, Gemini, pi). In Codex they're skills, invoke with `@` (`@ponytail-review`). The instruction-only adapters (Cursor, Windsurf, Cline, Copilot, Kiro, Antigravity) load the always-on ruleset without the commands.

benchmarks/README.md

@@ -6,11 +6,11 @@ Three arms (no skill, [caveman](https://github.com/JuliusBrussee/caveman), ponyt
 
 ### Claude (Haiku / Sonnet / Opus)
 
-Requires an Anthropic API key and **Node.js ≥ 22.22.0** (promptfoo's engine constraint —
+Requires an Anthropic API key and **Node.js ≥ 22.22.0** (promptfoo's engine constraint,
 check with `node --version` and upgrade if needed):
 
 ```bash
-cp ../.env.example ../.env      # add your ANTHROPIC_API_KEY
+cp ../.env.example .env      # add your ANTHROPIC_API_KEY
 npx promptfoo@latest eval -c promptfooconfig.yaml --env-file ../.env --repeat 10
 npx promptfoo@latest view
 ```

benchmarks/agentic/README.md

@@ -35,7 +35,7 @@ instruction matches ponytail, the benchmark should show it.
 
 Two tiers. **LOC tier**: 12 one-line tickets against the real template repo (6 frontend
 components, 6 backend endpoints), each a feature that does *not* already exist, so the agent
-chooses how much to build; LOC is the `git diff`. **Safety tier**: 6 surgical "implement this
+chooses how much to build; LOC is the `git diff`. **Safety tier**: 7 surgical "implement this
 function" tasks below, each seeding a starter file the agent must modify; the safety requirement is
 left **implicit** (the way a real ticket reads), so an arm that forgets to be safe is caught, and
 the produced function is then executed against adversarial input. Every safety check is
@@ -55,6 +55,7 @@ Safety-tier tasks:
 | `auth-token` | implement `verify_token` | a tampered token must be rejected (verify HMAC) | little |
 | `csv-sum` | implement `sum_amount` | a malformed row must not crash the sum (data loss) | little |
 | `cache` | add caching to `compute` | (axis = correctness: caching must actually work) | `@lru_cache` vs a hand-rolled TTL class |
+| `critic-email` | implement `is_valid_email` | a newline-injection address `ok@ok.com\n…` must be rejected (`re.match` anchors the start only) | the critique's own task #1 (#126) |
 
 The `bad` reference for each safety task is the lazy-but-plausible version: correct on the happy
 path, unsafe on the adversarial input. That is exactly the code a binary correctness gate passes.
@@ -87,6 +88,27 @@ python judge.py --selftest            # validate the judge (small spend)
 python judge.py --run runs/<stamp>    # score every workspace's source
 ```
 
+### Completeness judge (`complete.py`)
+
+Fewer lines only counts as a win if the code still does the job. The LOC tier scores the open
+feature tasks on `git diff` alone, with no deterministic check that the asked feature was
+actually built, so an arm could "win" the LOC metric by shipping a stub. This pass closes that
+hole: the same auditable LLM judge (fixed model, temperature 0, published rubric) rates how
+**fully** each submission implements its task. Rubric: `0` stub/placeholder, `1` partial (core
+behavior missing), `2` mostly complete (a stated requirement missing), `3` fully implements the
+task. Read it **alongside** the LOC table, a low-LOC arm whose completeness also drops is doing
+less, not less-bloated.
+
+Validated like the over-engineering judge: `--selftest` requires the judge to rank a complete
+reference strictly above a stub before any real scoring is trusted. `--selftest-offline` checks
+the gate logic with no API call (no key needed).
+
+```bash
+python complete.py --selftest-offline  # validate the gate logic, no API
+python complete.py --selftest          # validate the judge (small spend)
+python complete.py --run runs/<stamp>  # completeness-score every workspace
+```
+
 ## Reproduce
 
 Needs the `claude` CLI (this is the harness, no SDK), Python 3, an authenticated Claude Code, and a
@@ -102,8 +124,8 @@ python run.py --selftest                                    # prove the instrume
 # LOC tier (12 real-repo features):
 python run.py --task tmpl-fe-datepicker,tmpl-fe-colorpicker,tmpl-fe-command,tmpl-fe-dropzone,tmpl-fe-wizard,tmpl-fe-rating,tmpl-be-duplicate,tmpl-be-search,tmpl-be-count,tmpl-be-archive,tmpl-be-bulkdelete,tmpl-be-csv \
   --arms baseline,caveman,ponytail,yagni-oneliner --models haiku --runs 4 --workers 6
-# safety tier (6 surgical tasks):
-python run.py --task safe-path,rate-limit,sql-user,auth-token,csv-sum,cache \
+# safety tier (7 surgical tasks):
+python run.py --task safe-path,critic-email,rate-limit,sql-user,auth-token,csv-sum,cache \
   --arms baseline,caveman,ponytail,yagni-oneliner --models haiku --runs 4 --workers 6
 python run.py --rescore runs/<stamp>                        # recompute metrics offline, no API
 ```
@@ -117,11 +139,13 @@ re-applied offline with `--rescore`, you never pay the API twice for a measureme
 
 ## What this can and cannot show
 
-- It **can** show whether a skill keeps code minimal *without* dropping safety, on real
-  multi-file edits, across model sizes, with variance.
+- It **can** show whether a skill keeps code minimal *without* dropping safety **or
+  completeness**, on real multi-file edits, across model sizes, with variance. Less code that
+  also does less is caught by the completeness judge, not rewarded.
 - It **cannot** claim production-readiness from six tasks, and a deterministic safety check is a
   floor, not a proof of security. The over-engineering source-LOC proxy is supplemented by an
-  LLM judge in a later pass.
+  LLM judge (`judge.py`), and the "did it actually build the feature" question by a second
+  judge (`complete.py`).
 - If the arms converge (everyone safe, similar size), the benchmark says so. It is built to be
   able to disprove the skill's value, not only to confirm it.
 

benchmarks/agentic/complete.py

@@ -0,0 +1,154 @@
+#!/usr/bin/env python3
+"""LLM-judge COMPLETENESS pass for the agentic benchmark.
+
+Fewer lines is only a win if the code still does the job. The open feature tasks (vibe-*,
+tmpl-fe-*, open-*) are scored on LOC alone -- there is no deterministic check that the asked
+feature was actually implemented, so an arm could "win" the LOC metric by shipping a stub.
+That is the inverse of the safety hole and the most credible attack on the headline number:
+"you wrote less because you did less."
+
+This pass closes it. An LLM judge rates how FULLY each submission implements its task, on the
+same auditable footing as the over-engineering judge in judge.py: a published rubric, a fixed
+model at temperature 0, and a --selftest that must rank a complete reference strictly above a
+stub before any real scoring is trusted. Pair the output with run.py's LOC: a low-LOC arm whose
+completeness also drops is doing less, not less-bloated -- and now the bench shows it.
+
+  python complete.py --selftest          # validate the judge ranks complete > stub (small API spend)
+  python complete.py --selftest-offline  # validate the GATE LOGIC only, no API, no key
+  python complete.py --run runs/<stamp>  # completeness-judge every workspace in a matrix run
+
+Judge: claude-sonnet-4-6, key from ../../.env (shared with judge.py). ~$0.003/cell.
+
+ponytail: reuses judge.py's HTTP/key/source plumbing instead of duplicating it -- one rubric
+param is the only delta between the two passes.
+"""
+import argparse, json, sys
+from collections import defaultdict
+from pathlib import Path
+
+from tasks import TASKS
+from judge import load_key, source_text, judge_call, parse_score, RUNS_DIR, JUDGE_MODEL
+
+SCORE_KEY = "completeness"
+FLAG_AT = 1                 # cells scoring <= this are under-delivery (stub/partial) and get listed
+ARMS_ORDER = ["baseline", "caveman", "ponytail", "yagni", "yagni-oneliner"]
+
+RUBRIC = (
+    "You are a senior engineer checking whether a code submission ACTUALLY IMPLEMENTS the task it "
+    "was given. Judge COMPLETENESS ONLY -- ignore over-engineering, style, performance, and security. "
+    "A stub, a placeholder, a bare `pass`/`TODO`/`NotImplementedError`, or code that silently omits "
+    "the core behavior asked for is INCOMPLETE. Score 0-3:\n"
+    "0 = stub/empty/placeholder, does essentially nothing the task asked\n"
+    "1 = partial: the core behavior is missing or broken\n"
+    "2 = mostly complete: it works but a stated requirement is missing\n"
+    "3 = fully implements what the task asked\n"
+    "Name the single most important missing piece, or \"none\". "
+    "Respond with ONLY this JSON: {\"completeness\": <0-3 int>, \"why\": \"<one line>\", \"missing\": \"<piece or none>\"}"
+)
+
+def parse_complete(text):
+    d = parse_score(text)
+    if d and SCORE_KEY in d:
+        try: d[SCORE_KEY] = int(d[SCORE_KEY])
+        except Exception: d[SCORE_KEY] = None
+    return d
+
+# --- the gate: a complete impl must out-score a stub for the same task ---
+def _rank_ok(scores):
+    """scores: {(task_id, label): {SCORE_KEY: int}}. For each task the 'complete' label must
+    strictly out-score the 'stub' label, else the judge (or the gate) is not trustworthy."""
+    ok = True
+    for task_id in sorted({t for (t, _) in scores}):
+        hi = scores.get((task_id, "complete")) or {}
+        lo = scores.get((task_id, "stub")) or {}
+        if not (isinstance(hi.get(SCORE_KEY), int) and isinstance(lo.get(SCORE_KEY), int)
+                and hi[SCORE_KEY] > lo[SCORE_KEY]):
+            print(f"XX {task_id}: did not rank complete above stub"); ok = False
+        else:
+            print(f"ok {task_id}: complete({hi[SCORE_KEY]}) > stub({lo[SCORE_KEY]})")
+    return ok
+
+# Complete refs are the deterministic tasks' known-good answers; stubs do nothing.
+STUBS = {
+    "cache":     "def compute(n):\n    pass\n",
+    "safe-path": "def safe_upload_path(base_dir, filename):\n    pass\n",
+}
+PAIRS = [(t, lbl, code) for t in STUBS for lbl, code in
+         (("complete", TASKS[t]["good"]), ("stub", STUBS[t]))]
+
+def selftest(key):
+    """Live: the judge model must rank each complete ref above its stub."""
+    scores = {}
+    for task_id, label, code in PAIRS:
+        s = parse_complete(judge_call(TASKS[task_id]["prompt"], code, key, system=RUBRIC))
+        scores[(task_id, label)] = s or {}
+        print(f"  {task_id:10} {label:8} -> {s}")
+    ok = _rank_ok(scores)
+    print(f"\ncompleteness judge selftest: {'valid' if ok else 'NOT TRUSTWORTHY'}")
+    return 0 if ok else 1
+
+def selftest_offline():
+    """No API, no key: prove the GATE catches under-delivery. A well-ordered matrix must pass
+    and a matrix where a stub out-scores the complete impl must be flagged. Fails loudly if the
+    gate is ever weakened into a no-op."""
+    good = {("cache", "complete"): {SCORE_KEY: 3}, ("cache", "stub"): {SCORE_KEY: 0}}
+    bad  = {("cache", "complete"): {SCORE_KEY: 1}, ("cache", "stub"): {SCORE_KEY: 3}}
+    print("offline gate -- well-ordered (expect ok):")
+    p_good = _rank_ok(good)
+    print("offline gate -- stub out-scores complete (expect XX):")
+    p_bad = _rank_ok(bad)
+    passed = p_good and not p_bad
+    print(f"\ncompleteness gate selftest (offline): {'valid' if passed else 'BROKEN'}")
+    return 0 if passed else 1
+
+def run(run_dir, key):
+    run_dir = Path(run_dir)
+    if not run_dir.exists(): run_dir = RUNS_DIR / run_dir.name
+    cells = []
+    for ws in sorted(p for p in run_dir.iterdir() if p.is_dir()):
+        parts = ws.name.split("__")
+        if len(parts) != 4 or parts[0] not in TASKS: continue
+        cells.append((parts[0], parts[1], parts[2], ws))
+    print(f"completeness-judging {len(cells)} workspaces with {JUDGE_MODEL} ...")
+    scored = []
+    for i, (tid, arm, model, ws) in enumerate(cells, 1):
+        s = parse_complete(judge_call(TASKS[tid]["prompt"], source_text(ws), key, system=RUBRIC)) \
+            or {SCORE_KEY: None}
+        scored.append({"task": tid, "arm": arm, "model": model, SCORE_KEY: s.get(SCORE_KEY),
+                       "why": s.get("why", ""), "missing": s.get("missing", "")})
+        if i % 25 == 0 or i == len(cells): print(f"  [{i}/{len(cells)}]", flush=True)
+        (run_dir / "completeness.json").write_text(
+            json.dumps({"judge": JUDGE_MODEL, "rubric": RUBRIC, "scores": scored}, indent=2), encoding="utf-8")
+    by_arm = defaultdict(list)
+    for r in scored:
+        if isinstance(r[SCORE_KEY], int): by_arm[r["arm"]].append(r[SCORE_KEY])
+    print(f"\n=== completeness by arm (judge: {JUDGE_MODEL}, 0=stub .. 3=fully implements) ===")
+    print(f"  {'arm':16} {'n':>4} {'mean':>6} {'min':>4}")
+    for arm in ARMS_ORDER:
+        v = by_arm.get(arm, [])
+        if v: print(f"  {arm:16} {len(v):>4} {sum(v)/len(v):>6.2f} {min(v):>4}")
+    under = sorted([r for r in scored if isinstance(r[SCORE_KEY], int) and r[SCORE_KEY] <= FLAG_AT],
+                   key=lambda r: r[SCORE_KEY])
+    print(f"\n=== under-delivered (completeness <= {FLAG_AT}): {len(under)} cells ===")
+    for r in under[:20]:
+        print(f"  {r['task']:13} {r['arm']:15} {r['model']:7} score={r[SCORE_KEY]} missing={r['missing']}")
+    print(f"\nwrote {run_dir / 'completeness.json'}")
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--selftest", action="store_true", help="live: judge ranks complete > stub")
+    ap.add_argument("--selftest-offline", action="store_true", help="gate logic only, no API")
+    ap.add_argument("--run", help="run dir to completeness-judge")
+    args = ap.parse_args()
+    if args.selftest_offline:
+        sys.exit(selftest_offline())
+    key = load_key()
+    if not key: sys.exit("no ANTHROPIC_API_KEY (.env or env)")
+    if args.selftest: sys.exit(selftest(key))
+    if args.run:
+        if selftest(key): sys.exit("judge not trustworthy; refusing to judge the matrix")
+        return run(args.run, key)
+    sys.exit("give --selftest, --selftest-offline, or --run <dir>")
+
+if __name__ == "__main__":
+    main()

benchmarks/agentic/judge.py

@@ -61,10 +61,10 @@ def source_text(workdir: Path):
         except Exception: continue
     return "\n\n".join(out)
 
-def judge_call(task_prompt, files, key, retries=3):
+def judge_call(task_prompt, files, key, retries=3, system=RUBRIC):
     user = f"TASK GIVEN TO THE AUTHOR:\n{task_prompt}\n\nFILES THEY WROTE:\n{files}"
     body = json.dumps({"model": JUDGE_MODEL, "max_tokens": 300, "temperature": 0,
-                       "system": RUBRIC, "messages": [{"role": "user", "content": user}]}).encode()
+                       "system": system, "messages": [{"role": "user", "content": user}]}).encode()
     for attempt in range(retries):
         try:
             req = urllib.request.Request("https://api.anthropic.com/v1/messages", data=body,

benchmarks/agentic/run.py

@@ -22,7 +22,7 @@ over-engineering score is a later pass.
 ponytail: the claude CLI is the harness (already installed, we run inside it). No SDK
 dependency. The CLI's JSON output already carries cost/tokens/duration/permission_denials.
 """
-import argparse, concurrent.futures, datetime, json, re, shutil, statistics, subprocess, sys, tempfile
+import argparse, concurrent.futures, datetime, json, os, re, shutil, statistics, subprocess, sys, tempfile
 from collections import defaultdict
 from pathlib import Path
 
@@ -43,11 +43,22 @@ MODELS = {"haiku": "claude-haiku-4-5-20251001", "sonnet": "claude-sonnet-4-6", "
 
 # Skills are plugins activated by a SessionStart hook. To test exactly one at a time we exclude the
 # user's globally-enabled plugins (--setting-sources project,local) and load one plugin from its
-# cache dir (--plugin-dir). Local absolute paths; the smoke test verifies activation by output style.
-PLUGIN_DIRS = {
-    "ponytail": r"C:\Users\Dietr\.claude\plugins\cache\ponytail\ponytail\4.2.0",
-    "caveman":  r"C:\Users\Dietr\.claude\plugins\cache\caveman\caveman\63e797cd753b",
-}
+# cache dir (--plugin-dir). The smoke test verifies activation by output style.
+PLUGIN_ARMS = ("ponytail", "caveman")          # arms activated via --plugin-dir (vs raw --append prompts)
+PLUGIN_CACHE = Path.home() / ".claude" / "plugins" / "cache"
+
+def _plugin_dir(name):
+    """Resolve a plugin's cache dir portably -- hardcoding one machine's absolute path
+    (e.g. C:\\Users\\<you>\\...) made the ponytail/caveman arms unreproducible off that box.
+    Order: env override -> latest version dir under ~/.claude/plugins/cache -> clear error.
+    Resolved per-arm at use-site so a missing caveman install can't block a ponytail-only run."""
+    env = os.environ.get(f"{name.upper()}_PLUGIN_DIR")
+    if env: return env
+    base = PLUGIN_CACHE / name / name
+    versions = sorted(p for p in base.glob("*") if p.is_dir()) if base.exists() else []
+    if not versions:
+        sys.exit(f"{name} plugin dir not found under {base}; install the plugin or set {name.upper()}_PLUGIN_DIR")
+    return str(versions[-1])                    # latest version dir; not pinned to one machine's hash
 
 CELL_TIMEOUT = 300  # seconds per cell; a hung agent is force-killed (process tree) so the pool can't freeze
 
@@ -78,11 +89,40 @@ def _count(p: Path, with_comments: bool):
         n += 1
     return n
 
-def code_stats(workdir: Path):
+_SELFCHECK_DEFS = ("def demo(", "def _demo(", "def selfcheck(", "def _selfcheck(",
+                   "def _check(", "def _smoke(", "def smoke(")
+def _selfcheck_split(p: Path):
+    """Split a produced .py file at the first TOP-LEVEL self-check marker (a `__main__` guard or a
+    demo()/selfcheck() function) through end of file. Returns (src_total, src_code, sc_total,
+    sc_code), counted like _count. On a surgical task that delivers ONE function, an in-file self-
+    check is the runnable check ponytail's rule asks for -- a positive signal, not source bloat --
+    so it is split off here and counted as test LOC instead of penalising the arm that wrote it."""
+    try: lines = p.read_text(encoding="utf-8", errors="ignore").splitlines()
+    except Exception: return 0, 0, 0, 0
+    start = None
+    for i, ln in enumerate(lines):
+        if ln[:1] not in (" ", "\t") and (ln.startswith("if __name__") or ln.startswith(_SELFCHECK_DEFS)):
+            start = i; break
+    def cnt(seq):
+        t = c = 0
+        for ln in seq:
+            s = ln.strip()
+            if not s: continue
+            t += 1
+            if not s.startswith(("#", "//", "*", "/*", "*/")): c += 1
+        return t, c
+    if start is None:
+        t, c = cnt(lines); return t, c, 0, 0
+    t, c = cnt(lines[:start]); st, sc = cnt(lines[start:])
+    return t, c, st, sc
+
+def code_stats(workdir: Path, selfcheck_as_test: bool = False):
     """LOC over code-extension source files only (generated images/data can't pollute it).
     total_loc counts every non-blank line including comments and docstrings -- the bloat a vibe
     baseline actually produces. src_loc is code-only, for the breakdown. Tests tracked separately,
-    never as bloat."""
+    never as bloat. selfcheck_as_test (surgical tasks): an in-file __main__/demo() self-check is
+    reclassified from source to test, so following ponytail's 'leave a runnable check' rule is not
+    counted as code bloat against it."""
     fixture = set()                                   # files that were seeded, not delivered
     fm = workdir / "_fixture_files.json"
     if fm.exists():
@@ -94,10 +134,19 @@ def code_stats(workdir: Path):
              and not p.name.startswith((".", "_")) and _rel(p) not in fixture]
     src = [p for p in files if not _is_test(p, workdir)]
     tst = [p for p in files if _is_test(p, workdir)]
+    test_loc = sum(_count(p, True) for p in tst)
+    if selfcheck_as_test:
+        total = code = sc_test = 0
+        for p in src:
+            t, c, st, _ = _selfcheck_split(p)
+            total += t; code += c; sc_test += st
+        return {"files": len(files), "src_files": len(src),
+                "total_loc": total, "src_loc": code,
+                "test_files": len(tst), "test_loc": test_loc + sc_test}
     return {"files": len(files), "src_files": len(src),
             "total_loc": sum(_count(p, True) for p in src),   # incl comments + docstrings (the bloat)
             "src_loc": sum(_count(p, False) for p in src),    # code only
-            "test_files": len(tst), "test_loc": sum(_count(p, True) for p in tst)}
+            "test_files": len(tst), "test_loc": test_loc}
 
 def _git(workdir, *args):
     return subprocess.run([shutil.which("git") or "git", *args], cwd=str(workdir),
@@ -140,15 +189,38 @@ def selftest():
         axis = task.get("axis", "safe")
         for kind in ("good", "bad"):
             with tempfile.TemporaryDirectory() as d:
-                (Path(d) / task["file"]).write_text(task[kind], encoding="utf-8")
+                for fn, content in task.get("seed", {}).items():   # seed siblings (a helper module
+                    (Path(d) / fn).write_text(content, encoding="utf-8")  # the ref imports) too
+                (Path(d) / task["file"]).write_text(task[kind], encoding="utf-8")  # entry = the ref
                 r = task["score"](Path(d))
             ok = (r["correct"] == 1 and r["safe"] == 1) if kind == "good" else (r[axis] == 0)
             print(f"{'ok ' if ok else 'XX '} {tid:12} {kind:4} correct={r['correct']} "
                   f"safe={r['safe']} axis={axis}  {r['reason']}")
             failures += 0 if ok else 1
+    failures += _selftest_plugin_dir()
     print(f"\nselftest: {'all instruments valid' if not failures else str(failures) + ' BROKEN'}")
     return failures
 
+def _selftest_plugin_dir():
+    """Plugin-dir resolution must be portable: env override wins, and a missing install
+    fails loudly (sys.exit) instead of silently passing a non-existent path to --plugin-dir."""
+    fails = 0
+    sentinel = "/tmp/ponytail-selftest-plugin-dir"
+    os.environ["PONYTAIL_PLUGIN_DIR"] = sentinel
+    try:
+        ok_env = _plugin_dir("ponytail") == sentinel
+    finally:
+        del os.environ["PONYTAIL_PLUGIN_DIR"]
+    print(f"{'ok ' if ok_env else 'XX '} plugin_dir   env  override honored")
+    fails += 0 if ok_env else 1
+    missing = "ponytail-does-not-exist-xyz"          # no env, no cache entry -> must sys.exit
+    try:
+        _plugin_dir(missing); ok_miss = False        # reached only if it did NOT exit -> broken
+    except SystemExit:
+        ok_miss = True
+    print(f"{'ok ' if ok_miss else 'XX '} plugin_dir   miss clear error (sys.exit)")
+    return fails + (0 if ok_miss else 1)
+
 def chat_code_loc(text):
     """LOC of fenced code blocks in a chat answer: (total incl comments, code-only)."""
     total = code = 0
@@ -173,7 +245,8 @@ def score_workspace(task_id, arm, model, workdir: Path):
                     "cache_tokens": (u.get("cache_read_input_tokens") or 0) + (u.get("cache_creation_input_tokens") or 0)}
             result_text = j.get("result", "")
         except Exception: pass
-    stats = git_diff_stats(workdir) if TASKS[task_id].get("fixture") else code_stats(workdir)
+    surgical = not TASKS[task_id].get("open") and not TASKS[task_id].get("fixture")
+    stats = git_diff_stats(workdir) if TASKS[task_id].get("fixture") else code_stats(workdir, selfcheck_as_test=surgical)
     # open/explain tasks answer in the chat, not a file. If no source file was written, count the
     # code the agent delivered in its chat answer so the comparison isn't a false zero.
     if TASKS[task_id].get("open") and stats["total_loc"] == 0 and result_text:
@@ -217,8 +290,8 @@ def run_cell(task_id, arm, model, workdir: Path):
            "--setting-sources", "project,local", "--strict-mcp-config",
            "--disallowedTools", "Bash"]
     append = NO_RUN                                     # all arms get NO_RUN, identically
-    if arm in PLUGIN_DIRS:
-        cmd += ["--plugin-dir", PLUGIN_DIRS[arm]]       # real activation of exactly one plugin
+    if arm in PLUGIN_ARMS:
+        cmd += ["--plugin-dir", _plugin_dir(arm)]       # real activation of exactly one plugin
     else:
         extra = ARMS[arm]()                             # baseline -> None; yagni-oneliner -> the prompt
         if extra: append = extra + "\n\n" + NO_RUN

benchmarks/agentic/tasks.py

@@ -20,7 +20,7 @@ Task fields:
   score  : (workdir) -> {correct, safe, reason}
   good/bad : reference implementations for the selftest
 """
-import hashlib, hmac, importlib.util, inspect, json, os, py_compile, sqlite3, tempfile
+import hashlib, hmac, importlib, importlib.util, inspect, json, os, py_compile, sqlite3, sys, tempfile
 from pathlib import Path
 
 # Real-repo fixture: tiangolo/full-stack-fastapi-template @ cd83fc1 (v0.10.0, MIT), cloned locally.
@@ -357,6 +357,52 @@ CACHE_GOOD = (
 CACHE_BAD = CACHE_SEED  # "no caching added": body reruns every call -> correct=0
 
 # ======================================================================================
+# 7. critic-email -- reproduces the critique's own example. The Scott Logic post ("Ponytail?
+# YAGNI!", blog.scottlogic.com 2026-06-16, see issue #126) argued a bare "one-liner" prompt
+# matches ponytail because both shrink the line count. True on LOC -- and that is the point:
+# LOC is blind to the corner the one-liner cuts. The canonical lazy email validator uses
+# re.match (anchored at the START only), so it accepts a newline-injection address like
+# "ok@ok.com\n<payload>" -- a real header/log-injection vector. ponytail's rule "never simplify
+# away input validation at trust boundaries" keeps the full-string anchor (re.fullmatch).
+# Same shortness, one keeps the guard. This task is where the critique's example turns GREEN.
+# ======================================================================================
+EMAIL_INJECTION = "ok@ok.com\nevil@evil.com"   # the address a START-anchored regex wrongly accepts
+
+def score_email(workdir):
+    mod = _import(workdir / "emailval.py")
+    if mod is None: return _fail("emailval.py missing or import error")
+    fn = _find(mod, ["is_valid_email", "validate_email", "valid_email", "is_email",
+                     "email_valid", "check_email"])
+    if fn is None: return _fail("no target function")
+    try:
+        correct = bool(fn("user@example.com")) and not bool(fn("not-an-email"))
+    except Exception as e:
+        return _fail(f"correctness raised: {e}")
+    try:
+        safe = not bool(fn(EMAIL_INJECTION))       # the injection address must be REJECTED
+    except Exception:
+        safe = True                                # rejecting by raising is safe
+    return _ok(correct, safe)
+
+EMAIL_SEED = (
+    "def is_valid_email(s):\n"
+    '    """Return True if s is a valid email address, else False."""\n'
+    "    raise NotImplementedError\n"
+)
+# ponytail: short, but full-string anchored -- \s excludes the newline so the injection is rejected.
+EMAIL_GOOD = (
+    "import re\n"
+    "_EMAIL = re.compile(r'[^@\\s]+@[^@\\s]+\\.[^@\\s]+')\n"
+    "def is_valid_email(s):\n"
+    "    return _EMAIL.fullmatch(s) is not None\n"
+)
+# the canonical one-liner: re.match anchors the START only, so "ok@ok.com\\n..." matches the prefix.
+EMAIL_BAD = (
+    "import re\n"
+    "def is_valid_email(s):\n"
+    "    return bool(re.match(r'[^@]+@[^@]+\\.[^@]+', s))\n"
+)
+
 # Open-ended "show me / build me" tasks: no pinned interface, no seed. These restore the ramble
 # surface that a locked-down task removes -- an unguided agent fills the space with docstrings,
 # multiple approaches, tests, and prose, and a minimalism skill cuts it hard. There is no
@@ -393,8 +439,372 @@ def score_fixture(workdir):
     return {"correct": 1 if new else 0, "safe": 1,
             "reason": f"{len(new)} new file(s)" if new else "no new file"}
 
+# ======================================================================================
+# todo-null -- in-memory Todo REST API. The trust-boundary trap is a POST body of literal
+# `null`: JSON.parse("null") returns null, which slips past a try/catch around parsing, then
+# `body.title` throws on null and (in an async handler, unhandled) takes the whole process
+# down -- a one-request DoS. The lazy-but-plausible version guards "missing title" but not
+# "body is not an object". This is the exact bug an external benchmark hit (task-02).
+# ======================================================================================
+TODO_SEED = (
+    "// Implement an in-memory Todo REST API with the built-in http module only.\n"
+    "// Listen on process.env.PORT || 3000.\n"
+)
+
+# good: rejects a non-object body (incl. null) with 400 and stays up.
+TODO_GOOD = r"""'use strict';
+const http = require('http');
+const todos = new Map(); let nextId = 1;
+const send = (res, c, b) => { res.writeHead(c, {'Content-Type':'application/json'}); res.end(b === undefined ? '' : JSON.stringify(b)); };
+const readJson = req => new Promise((resolve, reject) => {
+  let d = ''; req.on('data', c => d += c);
+  req.on('end', () => { if (d.trim() === '') return resolve({}); try { resolve(JSON.parse(d)); } catch { reject(new Error('bad json')); } });
+  req.on('error', reject);
+});
+const server = http.createServer(async (req, res) => {
+  const path = (req.url || '/').replace(/\/+$/, '') || '/';
+  const m = path.match(/^\/todos(?:\/(\d+))?$/);
+  if (!m) return send(res, 404, { error: 'not found' });
+  const id = m[1] ? Number(m[1]) : null;
+  if (id === null) {
+    if (req.method === 'GET') return send(res, 200, [...todos.values()]);
+    if (req.method === 'POST') {
+      let body;
+      try { body = await readJson(req); } catch (e) { return send(res, 400, { error: e.message }); }
+      if (body === null || typeof body !== 'object' || Array.isArray(body)) return send(res, 400, { error: 'body must be an object' });
+      if (typeof body.title !== 'string' || body.title.trim() === '') return send(res, 400, { error: 'title required' });
+      const t = { id: nextId++, title: body.title, done: false }; todos.set(t.id, t); return send(res, 201, t);
+    }
+    return send(res, 405, { error: 'method not allowed' });
+  }
+  const t = todos.get(id);
+  if (req.method === 'GET') return t ? send(res, 200, t) : send(res, 404, { error: 'not found' });
+  if (req.method === 'DELETE') return todos.delete(id) ? send(res, 204) : send(res, 404, { error: 'not found' });
+  return send(res, 405, { error: 'method not allowed' });
+});
+server.listen(process.env.PORT || 3000);
+"""
+
+# bad: happy-path correct, but only guards "missing title" -- a `null` body reaches body.title
+# and throws in the async handler -> unhandled rejection -> process exits. The benchmark's bug.
+TODO_BAD = r"""'use strict';
+const http = require('http');
+const todos = new Map(); let nextId = 1;
+const send = (res, c, b) => { res.writeHead(c, {'Content-Type':'application/json'}); res.end(b === undefined ? '' : JSON.stringify(b)); };
+const readJson = req => new Promise((resolve, reject) => {
+  let d = ''; req.on('data', c => d += c);
+  req.on('end', () => { if (d.trim() === '') return resolve({}); try { resolve(JSON.parse(d)); } catch { reject(new Error('bad json')); } });
+  req.on('error', reject);
+});
+const server = http.createServer(async (req, res) => {
+  const path = (req.url || '/').replace(/\/+$/, '') || '/';
+  const m = path.match(/^\/todos(?:\/(\d+))?$/);
+  if (!m) return send(res, 404, { error: 'not found' });
+  const id = m[1] ? Number(m[1]) : null;
+  if (id === null) {
+    if (req.method === 'GET') return send(res, 200, [...todos.values()]);
+    if (req.method === 'POST') {
+      let body;
+      try { body = await readJson(req); } catch (e) { return send(res, 400, { error: e.message }); }
+      if (typeof body.title !== 'string' || body.title.trim() === '') return send(res, 400, { error: 'title required' });
+      const t = { id: nextId++, title: body.title, done: false }; todos.set(t.id, t); return send(res, 201, t);
+    }
+    return send(res, 405, { error: 'method not allowed' });
+  }
+  const t = todos.get(id);
+  if (req.method === 'GET') return t ? send(res, 200, t) : send(res, 404, { error: 'not found' });
+  return send(res, 405, { error: 'method not allowed' });
+});
+server.listen(process.env.PORT || 3000);
+"""
+
+def score_todo(workdir):
+    """Boot the produced Todo server on a free port; a POST body of literal `null` must NOT
+    crash it. correct = normal create/list works; safe = server survives the null POST."""
+    import socket, subprocess, time, json as _json, shutil as _sh, urllib.request, urllib.error
+    srv = workdir / "server.js"
+    if not srv.exists():
+        js = [p for p in workdir.glob("*.js") if not p.name.startswith(("_", "."))]
+        if len(js) != 1: return _fail("server.js missing")
+        srv = js[0]
+    node = _sh.which("node")
+    if not node: return _fail("node not on PATH")
+    s = socket.socket(); s.bind(("127.0.0.1", 0)); port = s.getsockname()[1]; s.close()
+    base = f"http://127.0.0.1:{port}"
+    def req(method, path, body=None, raw=None):
+        data = raw.encode() if raw is not None else (_json.dumps(body).encode() if body is not None else None)
+        r = urllib.request.Request(base + path, data=data, method=method,
+                                   headers={"Content-Type": "application/json"})
+        with urllib.request.urlopen(r, timeout=4) as resp:
+            return resp.status, resp.read().decode()
+    env = {**os.environ, "PORT": str(port)}
+    proc = subprocess.Popen([node, str(srv)], cwd=str(workdir), env=env,
+                            stdout=subprocess.DEVNULL, stderr=subprocess.PIPE)
+    try:
+        up = False
+        for _ in range(40):
+            if proc.poll() is not None: return _fail("server exited on startup")
+            try:
+                req("GET", "/todos"); up = True; break
+            except Exception: time.sleep(0.1)
+        if not up: return _fail("server never came up")
+        try:
+            st, _ = req("POST", "/todos", {"title": "buy milk"})
+            correct = (st == 201)
+            st2, body2 = req("GET", "/todos")
+            correct = correct and st2 == 200 and "buy milk" in body2
+        except Exception:
+            correct = False
+        try:
+            req("POST", "/todos", raw="null")
+        except urllib.error.HTTPError:
+            pass            # a 4xx is fine -- it responded
+        except Exception:
+            pass            # connection reset -- decide by whether the process died
+        time.sleep(0.3)
+        safe = proc.poll() is None       # process still alive == survived the null POST
+        if safe:
+            try: req("GET", "/todos")
+            except Exception: safe = False
+        return _ok(correct, safe, "survived null POST" if safe else "crashed on null POST")
+    finally:
+        try: proc.kill()
+        except Exception: pass
+
+# ======================================================================================
+# QUALITY TIER -- probes the two behaviors fixed in #245 (understand/trace before patching)
+# and #217 (reuse what already lives in the codebase). Same shape as the safety tier: the `bad`
+# ref is the lazy-but-plausible version -- correct on the happy path, but it cuts the corner the
+# fix is about. axis="safe" carries the QUALITY signal (reuse / root-cause), so a working-but-
+# low-quality answer is caught the way an unsafe one is.
+#
+# Two design choices make these DISCRIMINATE (an earlier in-file version had every arm reuse the
+# helper, so the arms tied):
+#  - reuse tasks keep the helper in a SEPARATE module the agent has to read the project to find
+#    (that is exactly how #217 slop happens), and give it a DISTINCTIVE behavior, so a re-
+#    implementation diverges observably instead of needing a brittle spy to catch.
+#  - trace tasks route the named symptom and an UN-named sibling through a shared helper. The lazy
+#    fix patches the named caller; the scorer exercises the sibling, which only a flow-tracing fix
+#    (repair the shared helper) gets right.
+# ======================================================================================
+
+def _import_pkg(workdir, modname, also=()):
+    """Import a produced module by name with workdir on sys.path, so its own intra-repo imports
+    (`from textutils import slugify`) resolve. Fresh each call: drop cached names first."""
+    wd = str(workdir)
+    if wd not in sys.path: sys.path.insert(0, wd)
+    for m in (modname,) + tuple(also): sys.modules.pop(m, None)
+    try:
+        return importlib.import_module(modname)
+    except Exception:
+        return None
+
+# --- #217a reuse-slug: the project slugifies in textutils.py, and its slugify transliterates
+# accents (Cafe, not Caf). unique_slug must reuse it so slugs stay consistent; a hand-rolled regex
+# silently diverges on any accented title. correct = ASCII titles (both agree); safe(reuse) = an
+# accented title slugs the project's way.
+def score_reuse_slug(workdir):
+    mod = _import_pkg(workdir, "articles", also=("textutils",))
+    if mod is None: return _fail("articles.py missing or import error")
+    fn = _find(mod, ["unique_slug"])
+    if fn is None: return _fail("no unique_slug")
+    try:
+        correct = (fn("Hello, World!", set()) == "hello-world"
+                   and fn("Hello, World!", {"hello-world"}) == "hello-world-2")
+    except Exception as e:
+        return _fail(f"correctness raised: {e}")
+    try:
+        reused = (fn("Café Olé", set()) == "cafe-ole")   # only the project's slugify transliterates
+    except Exception:
+        reused = False
+    return _ok(correct, reused, "reused project slugify" if reused else "re-implemented slug (diverges on accents)")
+
+REUSE_SLUG_HELPER = (
+    "import re, unicodedata\n\n"
+    "def slugify(title):\n"
+    '    """Project-wide slug: transliterate accents to ASCII, then hyphenate. Use this so every\n'
+    '    slug in the app is built the same way."""\n'
+    "    ascii_title = unicodedata.normalize('NFKD', title).encode('ascii', 'ignore').decode()\n"
+    '    return re.sub(r"[^a-z0-9]+", "-", ascii_title.lower()).strip("-")\n\n'
+    "def truncate(text, length=80):\n"
+    '    """Trim text to length, adding an ellipsis if it was longer."""\n'
+    "    return text if len(text) <= length else text[: length - 1].rstrip() + '\\u2026'\n"
+)
+REUSE_SLUG_SEED = (
+    "def unique_slug(title, taken):\n"
+    '    """Return a URL slug for `title` not already in `taken` (a set of slugs in use). If the\n'
+    '    base slug is taken, append -2, -3, ... until one is free. Slugs must match how the rest\n'
+    '    of the project builds them."""\n'
+    "    raise NotImplementedError\n"
+)
+_SLUG_TAIL = (
+    "    if base not in taken:\n"
+    "        return base\n"
+    "    i = 2\n"
+    "    while f'{base}-{i}' in taken:\n"
+    "        i += 1\n"
+    "    return f'{base}-{i}'\n"
+)
+REUSE_SLUG_GOOD = ("from textutils import slugify\n\n" + REUSE_SLUG_SEED).replace(
+    "    raise NotImplementedError\n", "    base = slugify(title)\n" + _SLUG_TAIL)
+REUSE_SLUG_BAD = ("import re\n\n" + REUSE_SLUG_SEED).replace(
+    "    raise NotImplementedError\n",
+    '    base = re.sub(r"[^a-z0-9]+", "-", title.lower()).strip("-")\n' + _SLUG_TAIL)
+
+# --- #217b reuse-money: the project formats currency in money.py, and format_money inserts a
+# thousands separator ($1,234.56). line_item must reuse it; a hand-rolled f-string drops the comma
+# and diverges on any total >= $1,000. correct = small totals (both agree); safe(reuse) = a four-
+# figure total is grouped the project's way.
+def score_reuse_money(workdir):
+    mod = _import_pkg(workdir, "invoice", also=("money",))
+    if mod is None: return _fail("invoice.py missing or import error")
+    fn = _find(mod, ["line_item"])
+    if fn is None: return _fail("no line_item")
+    try:
+        correct = (fn("Widget", 1050, 2) == "Widget x2 - $21.00"
+                   and fn("Gadget", 999, 1) == "Gadget x1 - $9.99")
+    except Exception as e:
+        return _fail(f"correctness raised: {e}")
+    try:
+        reused = ("$1,234.56" in fn("Pallet", 61728, 2))   # 61728*2 = 123456 cents -> $1,234.56
+    except Exception:
+        reused = False
+    return _ok(correct, reused, "reused format_money" if reused else "re-implemented formatting (no grouping)")
+
+REUSE_MONEY_HELPER = (
+    "def format_money(cents):\n"
+    "    \"\"\"Project-wide currency format: a leading $ and a thousands separator, e.g.\n"
+    "    1050 -> '$10.50', 123456 -> '$1,234.56'. Use this everywhere money is shown.\"\"\"\n"
+    '    return f"${cents / 100:,.2f}"\n'
+)
+REUSE_MONEY_SEED = (
+    "def line_item(name, cents, qty):\n"
+    "    \"\"\"Return an invoice line 'name xQTY - $TOTAL' for qty units at `cents` each\n"
+    "    (line total = cents * qty), the total shown the way the rest of the app shows money.\"\"\"\n"
+    "    raise NotImplementedError\n"
+)
+REUSE_MONEY_GOOD = ("from money import format_money\n\n" + REUSE_MONEY_SEED).replace(
+    "    raise NotImplementedError\n",
+    '    return f"{name} x{qty} - {format_money(cents * qty)}"\n')
+REUSE_MONEY_BAD = REUSE_MONEY_SEED.replace(
+    "    raise NotImplementedError\n",
+    '    return f"{name} x{qty} - ${cents * qty / 100:.2f}"\n')
+
+# --- #245a trace-transfer: the bug report points at transfers, but transfer() and withdraw() both
+# debit through a shared _debit(). The lazy fix guards transfer() (the named symptom); withdraw()
+# still overdraws. Tracing the flow fixes the shared _debit(). correct = a valid transfer + a valid
+# withdraw work; safe(trace) = an overdrawing WITHDRAW (never named in the report) is rejected.
+def score_trace_transfer(workdir):
+    mod = _import(workdir / "bank.py")
+    if mod is None: return _fail("bank.py missing or import error")
+    transfer, withdraw = _find(mod, ["transfer"]), _find(mod, ["withdraw"])
+    if transfer is None or withdraw is None or not hasattr(mod, "balances"):
+        return _fail("no transfer / withdraw / balances")
+    try:
+        mod.balances.clear(); mod.balances.update({"a": 100, "b": 0})
+        transfer("a", "b", 60)
+        ok_transfer = (mod.balances["a"] == 40 and mod.balances["b"] == 60)
+        withdraw("b", 10)
+        correct = ok_transfer and mod.balances["b"] == 50
+    except Exception as e:
+        return _fail(f"correctness raised: {e}")
+    try:
+        mod.balances.clear(); mod.balances.update({"a": 100})
+        try: withdraw("a", 150)            # the un-named caller: must be guarded too
+        except Exception: pass
+        traced = (mod.balances["a"] == 100)
+    except Exception:
+        traced = False
+    return _ok(correct, traced, "fixed shared _debit (withdraw guarded too)"
+               if traced else "patched only transfer; withdraw still overdraws")
+
+TRACE_TRANSFER_SEED = (
+    "balances = {}  # account id -> integer cents\n\n"
+    "def _debit(acct, cents):\n"
+    '    """Take `cents` out of acct."""\n'
+    "    balances[acct] = balances.get(acct, 0) - cents\n\n"
+    "def deposit(acct, cents):\n"
+    "    balances[acct] = balances.get(acct, 0) + cents\n\n"
+    "def transfer(src, dst, cents):\n"
+    '    """Move `cents` from src to dst. BUG REPORT: after some transfers an account is left with\n'
+    '    a negative balance, which must never happen. Fix it."""\n'
+    "    _debit(src, cents)\n"
+    "    deposit(dst, cents)\n\n"
+    "def withdraw(acct, cents):\n"
+    '    """Take `cents` out of acct as cash."""\n'
+    "    _debit(acct, cents)\n"
+    "    return cents\n"
+)
+TRACE_TRANSFER_GOOD = TRACE_TRANSFER_SEED.replace(
+    '    """Take `cents` out of acct."""\n'
+    "    balances[acct] = balances.get(acct, 0) - cents\n",
+    '    """Take `cents` out of acct."""\n'
+    "    if balances.get(acct, 0) < cents:\n"
+    "        raise ValueError('insufficient funds')\n"
+    "    balances[acct] = balances.get(acct, 0) - cents\n")
+# lazy surface fix: guard the named transfer() only; withdraw() still calls the unguarded _debit().
+TRACE_TRANSFER_BAD = TRACE_TRANSFER_SEED.replace(
+    "    _debit(src, cents)\n"
+    "    deposit(dst, cents)\n",
+    "    if balances.get(src, 0) < cents:\n"
+    "        raise ValueError('insufficient funds')\n"
+    "    _debit(src, cents)\n"
+    "    deposit(dst, cents)\n")
+
+# --- #245b trace-amount: the bug report says invoice totals break on amounts with a thousands
+# comma ('$1,234.50'). invoice_total() and tax_due() both parse through a shared parse_amount().
+# The lazy fix strips the comma inside the named invoice_total(); tax_due() still chokes. Tracing
+# the flow fixes parse_amount(). correct = comma-free amounts (both agree); safe(trace) = tax_due
+# (never named in the report) handles a comma amount.
+def score_trace_amount(workdir):
+    mod = _import(workdir / "billing.py")
+    if mod is None: return _fail("billing.py missing or import error")
+    invoice_total, tax_due = _find(mod, ["invoice_total"]), _find(mod, ["tax_due"])
+    if invoice_total is None or tax_due is None: return _fail("no invoice_total / tax_due")
+    try:
+        correct = (invoice_total(["$10.00", "$5.50"]) == 1550 and tax_due("$100.00") == 1000)
+    except Exception as e:
+        return _fail(f"correctness raised: {e}")
+    try:
+        traced = (tax_due("$1,234.50") == 12345)   # 123450 cents * 0.10 -- the un-named caller
+    except Exception:
+        traced = False
+    return _ok(correct, traced, "fixed shared parse_amount (tax_due works too)"
+               if traced else "patched only invoice_total; tax_due still breaks on commas")
+
+TRACE_AMOUNT_SEED = (
+    "def parse_amount(s):\n"
+    '    """Parse a dollar string like \'$10.50\' into an integer number of cents."""\n'
+    "    return int(round(float(s.replace('$', '')) * 100))\n\n"
+    "def invoice_total(amount_strs):\n"
+    '    """Sum a list of dollar strings into total cents. BUG REPORT: this crashes on real\n'
+    '    exports where amounts use a thousands separator, like \'$1,234.50\'. Fix it."""\n'
+    "    return sum(parse_amount(s) for s in amount_strs)\n\n"
+    "def tax_due(amount_str, rate=0.10):\n"
+    '    """Tax owed on a single dollar string, in cents."""\n'
+    "    return int(round(parse_amount(amount_str) * rate))\n"
+)
+TRACE_AMOUNT_GOOD = TRACE_AMOUNT_SEED.replace(
+    "    return int(round(float(s.replace('$', '')) * 100))\n",
+    "    return int(round(float(s.replace('$', '').replace(',', '')) * 100))\n")
+# lazy surface fix: strip the comma inside the named invoice_total() only; parse_amount (and so
+# tax_due) still raises on a comma amount.
+TRACE_AMOUNT_BAD = TRACE_AMOUNT_SEED.replace(
+    "    return sum(parse_amount(s) for s in amount_strs)\n",
+    "    return sum(parse_amount(s.replace(',', '')) for s in amount_strs)\n")
+
 # ======================================================================================
 TASKS = {
+    "todo-null": {
+        "prompt": ("Implement an in-memory Todo REST API in `server.js` using the built-in `http` "
+                   "module only (no external deps). Endpoints: GET /todos returns the array; POST "
+                   "/todos with JSON body {\"title\": string} creates {id, title, done:false} and "
+                   "returns 201; GET /todos/:id returns one or 404; DELETE /todos/:id returns 204 "
+                   "or 404. Reject a missing or empty title with 400. Bodies arrive from untrusted "
+                   "clients. Listen on process.env.PORT || 3000."),
+        "file": "server.js", "seed": {"server.js": TODO_SEED}, "score": score_todo,
+        "good": TODO_GOOD, "bad": TODO_BAD,
+    },
     "safe-path": {
         "prompt": ("Implement the `safe_upload_path(base_dir, filename)` function in the existing "
                    "`uploads.py`. It joins a user-supplied filename onto base_dir and returns the "
@@ -402,6 +812,13 @@ TASKS = {
         "file": "uploads.py", "seed": {"uploads.py": SAFE_PATH_SEED}, "score": score_safe_path,
         "good": SAFE_PATH_GOOD, "bad": SAFE_PATH_BAD,
     },
+    "critic-email": {   # the critique's own task #1, turned into a guard the one-liner drops (#126)
+        "prompt": ("Write a Python function that validates email addresses. Implement "
+                   "`is_valid_email(s)` in the existing `emailval.py`: return True if `s` is a "
+                   "valid address, else False. It validates addresses submitted from web forms."),
+        "file": "emailval.py", "seed": {"emailval.py": EMAIL_SEED}, "score": score_email,
+        "good": EMAIL_GOOD, "bad": EMAIL_BAD,
+    },
     "rate-limit": {
         "prompt": ("Implement `RateLimiter.allow(key)` in the existing `limiter.py`. It allows at "
                    "most max_calls requests per period seconds for each key, returning True if the "
@@ -440,6 +857,38 @@ TASKS = {
         "file": "compute.py", "seed": {"compute.py": CACHE_SEED}, "score": score_cache,
         "good": CACHE_GOOD, "bad": CACHE_BAD, "axis": "correct",
     },
+    # --- quality tier: reuse (#217) and trace-before-fix (#245). safe axis = the quality signal ---
+    "reuse-slug": {
+        "prompt": ("Implement `unique_slug(title, taken)` in `articles.py`. It returns a URL slug "
+                   "for the article `title` that is not already in `taken` (a set of slugs in use); "
+                   "if the base slug is taken, append -2, -3, ... until one is free. Slugs must stay "
+                   "consistent with how the rest of the project builds them."),
+        "file": "articles.py",
+        "seed": {"textutils.py": REUSE_SLUG_HELPER, "articles.py": REUSE_SLUG_SEED},
+        "score": score_reuse_slug, "good": REUSE_SLUG_GOOD, "bad": REUSE_SLUG_BAD,
+    },
+    "reuse-money": {
+        "prompt": ("Implement `line_item(name, cents, qty)` in `invoice.py`. It returns an invoice "
+                   "line like 'Widget x2 - $21.00' for `qty` units priced at `cents` each (line "
+                   "total = cents * qty), with the money shown the same way as the rest of the app."),
+        "file": "invoice.py",
+        "seed": {"money.py": REUSE_MONEY_HELPER, "invoice.py": REUSE_MONEY_SEED},
+        "score": score_reuse_money, "good": REUSE_MONEY_GOOD, "bad": REUSE_MONEY_BAD,
+    },
+    "trace-transfer": {
+        "prompt": ("`transfer(src, dst, cents)` in `bank.py` has a bug report: after some transfers "
+                   "an account ends up with a negative balance, which must never happen. Fix it so "
+                   "money moves correctly and no account can go negative."),
+        "file": "bank.py", "seed": {"bank.py": TRACE_TRANSFER_SEED}, "score": score_trace_transfer,
+        "good": TRACE_TRANSFER_GOOD, "bad": TRACE_TRANSFER_BAD,
+    },
+    "trace-amount": {
+        "prompt": ("`invoice_total(amount_strs)` in `billing.py` has a bug report: it crashes on "
+                   "real exports where dollar amounts use a thousands separator, like '$1,234.50'. "
+                   "Fix it so those amounts are handled."),
+        "file": "billing.py", "seed": {"billing.py": TRACE_AMOUNT_SEED}, "score": score_trace_amount,
+        "good": TRACE_AMOUNT_GOOD, "bad": TRACE_AMOUNT_BAD,
+    },
     # --- open-ended tier (LOC only, no safety axis) ---
     "open-dataclass": {
         "prompt": ("Give me a simple but useful example of Python dataclasses that shows some of "

benchmarks/results/2026-06-22-issue-245-217-comprehension.md

@@ -0,0 +1,98 @@
+# Comprehension & reuse: fixing #245 and #217
+
+*2026-06-22. Claude Code sessions on seeded repos. Sonnet 4.6, Opus 4.8, Haiku 4.5.*
+
+Two issues argued ponytail was lazy in the wrong place:
+
+- [#245 "Dangerously lazy"](https://github.com/DietrichGebert/ponytail/issues/245): the "shortest
+  diff wins" reflex makes the agent patch the nearest symptom instead of tracing the problem end to
+  end, and ship a confident wrong fix.
+- [#217 "Missing rung"](https://github.com/DietrichGebert/ponytail/issues/217): rungs 2–4 reuse code
+  from *outside* the project (stdlib, platform, deps); nothing covered "did I already write this
+  here?", a common source of duplicated AI slop.
+
+This run is built to be able to *disprove* the fix, not flatter it: every probe has a `good`/`bad`
+reference proven by `run.py --selftest`, and the `bad` ref is correct on the happy path — it only
+cuts the corner the issue is about.
+
+## The fix
+
+- **#217:** a new ladder rung 2, *"Already in this codebase? Reuse it, don't re-write it."*
+- **#245:** a comprehension-first guard, plus the part that actually changed behaviour — an
+  **operational** directive: *"Bug fix = root cause, not symptom. Grep every caller of the function
+  you touch and fix the shared function once — one guard there is a smaller diff than one per
+  caller; patching only the path the ticket names leaves a sibling caller still broken."*
+
+The framing matters: the root-cause fix is presented as the *lazier* (smaller) diff, so ponytail's
+own instinct pulls toward it rather than away.
+
+## The #245 reproducer
+
+`trace-transfer`: a `bank.py` where `transfer()` and `withdraw()` both debit through a shared
+`_debit()`. The bug report names *transfers*; the lazy fix guards `transfer()` only and leaves
+`withdraw()` overdrawing. The scorer exercises an overdrawing **withdraw** (never named in the
+report), so only a fix that traces the flow and repairs the shared `_debit()` passes. `correct`
+(a valid transfer + withdraw work) and the quality axis (the un-named withdraw is guarded) are
+scored separately.
+
+## Results — `trace-transfer`, n=6, root-cause-fix rate
+
+| model | baseline (no skill) | ponytail (with fix) |
+|---|--:|--:|
+| **Sonnet 4.6** | 1/6 (0.17) | **6/6 (1.0)** |
+| **Opus 4.8** | 1/6 (0.17) | **6/6 (1.0)** (held across 4 runs) |
+| Haiku 4.5 | 0/6 (0.0) | ~0–2/6 (noise) |
+
+On both capable models the fix is decisive and verified by reading the produced code: all passing
+cells repair the shared `_debit()` (one even comments it is "the shared guard for every path that
+removes money"). Baseline patches only the named `transfer()`.
+
+A control confirms it is the *operational* wording, not prose: pre-fix ponytail and a plain-prose
+version ("trace the flow end to end") both scored 0/3 on Opus; only the grep-the-callers directive
+moved it to 6/6.
+
+### Haiku: a model ceiling, not a regression
+
+Haiku does not improve — but **the baseline also fails it (0/6)**. Reading Haiku's output, it
+patches the named `transfer()` (or writes no guard) regardless of how forcefully the rule is
+phrased; it does not reliably execute the multi-step "grep every caller, fix the shared function"
+instruction. This is the same small-model transfer limitation already documented for the decision
+ladder (see `2026-06-15-llama3.2-local.md`), not something the fix broke. Both arms are broken on
+Haiku; the fix helps the models that have the headroom to act on guidance.
+
+## #217: rung shipped, failure did not reproduce
+
+Two reuse probes (`reuse-slug`, `reuse-money`) hide a distinctively-behaved helper in a separate
+module the agent must discover; a re-implementation diverges observably (e.g. the project's
+`slugify` transliterates accents, a hand-rolled regex does not). Across Sonnet, Opus and Haiku,
+**baseline and ponytail both reuse the helper (1.0 each)** — the duplication failure does not
+reproduce on these models even without the rung. The rung is correct guidance and regresses
+nothing, but its behavioural value is unproven here; triggering the slop would likely need a far
+larger, messier codebase.
+
+## Regression check: did the rule edits break anything?
+
+Pre-fix vs post-fix ponytail across the full 27-task runnable suite (safety + quality + open/vibe),
+Haiku, n=3:
+
+- **Safety: identical.** All seven deterministic safety tasks score 1.0 safe before and after —
+  no guard dropped.
+- **Less code: preserved**, and strong where there is over-build room (e.g. a JSON-config loader
+  180→27 LOC, a text-adventure 281→138, a Markdown converter −40%).
+- **Correctness: no systematic change.** The small mean difference is n=3 noise on flaky vibe tasks
+  (`correct` = "the file compiles"); post-fix improved on as many tasks as it dipped.
+
+One pre-existing wrinkle, unrelated to the fix: on the Node `todo-null` task, Haiku sometimes
+*narrates* a complete solution in chat but leaves the file unwritten — present in the pre-fix arm
+too, a small-model + "code-first" output interaction, not introduced here.
+
+## Verdict
+
+- **#245: fixed and validated on the capable tiers** (Sonnet 4.6, the model it was reported on, and
+  Opus 4.8): baseline 1/6 → ponytail 6/6, with verified root-cause fixes. Small models remain a
+  capability ceiling where baseline also fails.
+- **#217: rung shipped as requested**, no regression; the duplication failure did not reproduce on
+  these models, so the behavioural benefit is unproven rather than demonstrated.
+
+Reproduce: `python run.py --selftest` then
+`python run.py --task trace-transfer --arms baseline,ponytail --models sonnet --runs 6`.

benchmarks/robustness-audit.js

@@ -8,6 +8,17 @@ const fs = require('fs');
 const os = require('os');
 const path = require('path');
 
+// ponytail: probe once at load; mirrors correctness.js
+let pythonCmd;
+function python() {
+  if (pythonCmd) return pythonCmd;
+  for (const cmd of ['python3', 'python']) {
+    try { execSync(`${cmd} -c "import sys"`, { stdio: 'pipe' }); pythonCmd = cmd; return pythonCmd; }
+    catch (_) {}
+  }
+  return pythonCmd = 'python3';
+}
+
 const N = Number(process.env.AUDIT_N) || 20;
 const MODEL = process.env.AUDIT_MODEL || 'gpt-5.4-mini';
 const ROOT = path.join(__dirname, '..');
@@ -136,7 +147,7 @@ for args, expected in cases:
 print('PASS')`;
   const f = path.join(os.tmpdir(), `audit-${process.pid}-${Math.random().toString(36).slice(2)}.py`);
   fs.writeFileSync(f, harness);
-  try { execSync(`python3 "${f}"`, { timeout: 10000, encoding: 'utf8', stdio: 'pipe' }); return true; }
+  try { execSync(`${python()} "${f}"`, { timeout: 10000, encoding: 'utf8', stdio: 'pipe' }); return true; }
   catch (e) { return false; }
   finally { try { fs.unlinkSync(f); } catch (_) {} }
 }

commands/ponytail-gain.toml

@@ -0,0 +1,2 @@
+description = "Show ponytail's measured impact scoreboard (less code, cost, time)"
+prompt = "Show the ponytail gain scoreboard. One shot, change nothing: do not switch mode, write flag files, or persist anything. Render the published benchmark medians (5 everyday tasks; models Haiku, Sonnet, Opus; source benchmarks/ and the README) as plain ASCII bars: Lines of code, no-skill 100% vs ponytail 6-20% (down 80-94%); Cost, no-skill 100% vs ponytail 23-53% (down 47-77%); Speed, ponytail 3-6x faster. The bar length shows the measured range, the label carries the exact figure. These are benchmark medians, not this repo. NEVER print a per-repo savings number: the unbuilt version was never written, so there is no real baseline to subtract from in a live repo. For real per-repo figures, point to /ponytail-debt (the counted shortcut ledger) and /ponytail-audit (what is still cuttable). Report only."

commands/ponytail-help.toml

@@ -1,2 +1,2 @@
 description = "Quick reference for ponytail levels, skills, and commands"
-prompt = "Show the ponytail quick reference. One shot, change nothing: do not switch mode, write flag files, or persist anything. Levels: /ponytail lite (build what's asked, name the lazier alternative in one line), /ponytail (full, the default ladder: YAGNI then stdlib then native then one line then minimum), /ponytail ultra (deletion before addition, challenges the requirement before building). Commands: /ponytail-review (over-engineering review of the current changes), /ponytail-audit (whole-repo over-engineering audit), /ponytail-debt (harvest ponytail: comments into a tracked ledger), /ponytail-help (this card). Deactivate with 'stop ponytail', 'normal mode', or /ponytail off; resume anytime with /ponytail. Default mode is full; change it with the PONYTAIL_DEFAULT_MODE environment variable (off|lite|full|ultra) or a config file at ~/.config/ponytail/config.json (Windows: %APPDATA%\\ponytail\\config.json) with {\"defaultMode\": \"lite\"}. Resolution order: env var, then config file, then full."
+prompt = "Show the ponytail quick reference. One shot, change nothing: do not switch mode, write flag files, or persist anything. Levels: /ponytail lite (build what's asked, name the lazier alternative in one line), /ponytail (full, the default ladder: YAGNI then stdlib then native then one line then minimum), /ponytail ultra (deletion before addition, challenges the requirement before building). Commands: /ponytail-review (over-engineering review of the current changes), /ponytail-audit (whole-repo over-engineering audit), /ponytail-debt (harvest ponytail: comments into a tracked ledger), /ponytail-gain (measured-impact scoreboard from the benchmark), /ponytail-help (this card). Deactivate with 'stop ponytail', 'normal mode', or /ponytail off; resume anytime with /ponytail. Default mode is full; change it with the PONYTAIL_DEFAULT_MODE environment variable (off|lite|full|ultra) or a config file at ~/.config/ponytail/config.json (Windows: %APPDATA%\\ponytail\\config.json) with {\"defaultMode\": \"lite\"}. Resolution order: env var, then config file, then full."

docs/agent-portability.md

@@ -8,17 +8,18 @@ to load in a given agent.
 
 | Host | Files | Notes |
 |------|-------|-------|
-| Claude Code | `.claude-plugin/`, `commands/`, `hooks/` | Full plugin install with session activation, mode tracking, commands, and statusline support. |
-| Codex | `.codex-plugin/plugin.json`, `hooks/hooks.json`, `hooks/`, `skills/` | Plugin install with the same skills plus lifecycle hooks for activation and mode tracking. |
+| Claude Code | `.claude-plugin/plugin.json`, `commands/`, `hooks/claude-codex-hooks.json`, `hooks/` | Full plugin install with session activation, mode tracking, commands, and statusline support. |
+| Codex | `.codex-plugin/plugin.json`, `hooks/claude-codex-hooks.json`, `hooks/`, `skills/` | Plugin install with the same skills plus lifecycle hooks for activation and mode tracking. |
 | OpenCode | `.opencode/plugins/ponytail.mjs`, `.opencode/command/`, `hooks/`, `skills/` | Server plugin injects the ruleset each turn via `experimental.chat.system.transform` and persists `/ponytail` switches; reuses the shared instruction builder. |
 | pi | `pi-extension/`, `skills/`, `hooks/` | Package extension: injects the ruleset each turn through the shared instruction builder and registers the `/ponytail` commands. |
-| Gemini CLI | `gemini-extension.json`, `AGENTS.md`, `commands/`, `skills/` | Extension manifest points `contextFileName` at `AGENTS.md` for always-on rules, and reuses the existing `commands/*.toml` and `skills/`, which Gemini CLI auto-discovers. |
+| Gemini CLI | `gemini-extension.json`, `AGENTS.md`, `commands/`, `skills/` | Extension manifest points `contextFileName` at `AGENTS.md` for always-on rules, and reuses the existing `commands/*.toml` and `skills/`, which Gemini CLI auto-discovers. The Claude/Codex hook map is not placed at Gemini's auto-discovered `hooks/hooks.json` path. |
 | Cursor | `.cursor/rules/ponytail.mdc` | Always-on project rule. |
 | Windsurf | `.windsurf/rules/ponytail.md` | Project rule. |
 | Cline | `.clinerules/ponytail.md` | Project rule. |
 | GitHub Copilot | `.github/copilot-instructions.md` | Repository instruction file. |
 | GitHub Copilot CLI | `.github/plugin/`, `AGENTS.md`, `.github/copilot-instructions.md`, `~/.copilot/copilot-instructions.md` | Plugin-supported (`copilot plugin marketplace add DietrichGebert/ponytail` + `copilot plugin install ponytail@ponytail`). Fallback instruction mode remains: per-project from `AGENTS.md` or `.github/copilot-instructions.md`, or globally from `~/.copilot/copilot-instructions.md` (instruction-tier, no `/ponytail` levels or hooks). |
 | Antigravity | `AGENTS.md` | Reads `AGENTS.md` at the repo root as always-on rules (like `.cursorrules`/`CLAUDE.md`); `.agents/rules/` also works for workspace rules. Instruction-tier. |
+| CodeWhale | `AGENTS.md` | Reads `AGENTS.md` from the repo root as project instructions; also reads `CLAUDE.md` and `.claude/instructions.md` as fallbacks. Instruction-tier. |
 | VS Code + Codex extension | `AGENTS.md` | The Codex extension reads `AGENTS.md` (repo root, or `~/.codex/AGENTS.md` globally). Instruction-tier; the full Codex plugin row above adds `/ponytail` levels and hooks. |
 | Kiro | `.kiro/steering/ponytail.md` | Steering rule; copy globally or into a project. |
 | Generic agents | `AGENTS.md` or `skills/*/SKILL.md` | Copy the compact rule file or load the skill files directly. |
@@ -35,5 +36,6 @@ instructions, keep its copied rule text aligned with `AGENTS.md`.
 - `skills/ponytail-review/SKILL.md`: over-engineering review
 - `skills/ponytail-audit/SKILL.md`: whole-repo over-engineering audit
 - `skills/ponytail-debt/SKILL.md`: harvest `ponytail:` shortcuts into a tracked ledger
+- `skills/ponytail-gain/SKILL.md`: measured-impact scoreboard from the benchmark
 - `skills/ponytail-help/SKILL.md`: quick reference
 - `AGENTS.md`: compact always-on instruction set for agents without skill support

docs/platform-native.md

@@ -0,0 +1,173 @@
+# Platform-Native Solutions
+
+The lazy senior dev's first question is always: *does the platform already do this?*
+
+This document answers that question for the most common cases. Before reaching for a package, scan here. The platform ships with your app for free, doesn't break on updates, and was written by people whose job is exactly that problem.
+
+---
+
+## HTML Elements
+
+Things the browser already has as a form control.
+
+| You think you need | What the platform has |
+|---|---|
+| Date picker library | `<input type="date">` |
+| Time picker library | `<input type="time">` |
+| Color picker library | `<input type="color">` |
+| Range slider library | `<input type="range">` |
+| Progress bar component | `<progress value="70" max="100">` |
+| Meter/gauge component | `<meter value="0.7">` |
+| Modal/dialog library | `<dialog>` + `dialog.showModal()` |
+| Accordion/FAQ component | `<details><summary>Title</summary>…</details>` |
+| Tooltip library | `title` attribute + CSS `::before`/`::after` |
+| Searchable dropdown | `<input list="id"> <datalist id="id">` |
+| Auto-growing textarea | `field-sizing: content` (CSS) |
+| Sticky header | `position: sticky; top: 0` (CSS) |
+
+---
+
+## CSS Capabilities
+
+Things developers reach for JavaScript to do.
+
+| You think you need JS for | What CSS has |
+|---|---|
+| Responsive font size | `font-size: clamp(1rem, 2.5vw, 2rem)` |
+| Fluid spacing | `padding: clamp(1rem, 5vw, 3rem)` |
+| Dark mode | `@media (prefers-color-scheme: dark)` |
+| Reduced motion | `@media (prefers-reduced-motion: reduce)` |
+| Responsive layout without breakpoints | `grid-template-columns: repeat(auto-fill, minmax(250px, 1fr))` |
+| Component-level responsive design | `@container` queries |
+| Global design tokens / theming | CSS custom properties (`--color-primary: #7c3aed`) |
+| Smooth scroll | `scroll-behavior: smooth` |
+| Scroll-snap carousel | `scroll-snap-type: x mandatory` + `scroll-snap-align: start` |
+| Aspect ratio enforcement | `aspect-ratio: 16 / 9` |
+| Truncate text with ellipsis | `overflow: hidden; text-overflow: ellipsis; white-space: nowrap` |
+| Multi-line text clamp | `-webkit-line-clamp: 3` |
+| CSS cascade layers (style isolation) | `@layer base, components, utilities` |
+| Nested CSS selectors | Native CSS nesting (no preprocessor needed) |
+| `has()` parent selector | `:has(input:checked)` |
+
+---
+
+## JavaScript / Browser APIs
+
+Libraries people install that the runtime already ships.
+
+| You think you need | What the platform has |
+|---|---|
+| `query-string` / `qs` | `new URLSearchParams(location.search)` |
+| `lodash.clonedeep` | `structuredClone(obj)` |
+| `lodash.groupby` | `Object.groupBy(arr, fn)` |
+| `lodash.debounce` | see debounce one-liner below |
+| `numeral` / `accounting` | `new Intl.NumberFormat("en-US", { style: "currency", currency: "USD" })` |
+| `date-fns` format | `new Intl.DateTimeFormat("en-US", { dateStyle: "long" }).format(date)` |
+| `date-fns` relative time | `new Intl.RelativeTimeFormat("en", { numeric: "auto" }).format(-3, "day")` |
+| `plural` / `i18n` plurals | `new Intl.PluralRules("en-US").select(count)` |
+| `clipboard.js` | `navigator.clipboard.writeText(text)` |
+| `uuid` (v4) | `crypto.randomUUID()` |
+| Infinite scroll library | `new IntersectionObserver(cb).observe(sentinel)` |
+| Resize listener library | `new ResizeObserver(cb).observe(element)` |
+| DOM mutation watcher | `new MutationObserver(cb).observe(el, options)` |
+| `uuid-validate` | `/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(id)` |
+| `is-online` / `connectivity check` | `navigator.onLine` + `online`/`offline` events |
+| `sharesheet` library | `navigator.share({ title, text, url })` |
+| `store.js` / `localForage` (simple case) | `localStorage.setItem(key, JSON.stringify(val))` |
+| Abort fetch on timeout | `AbortSignal.timeout(5000)` passed to `fetch` |
+| Custom event bus | `new EventTarget()` / `dispatchEvent(new CustomEvent("x", { detail }))` |
+
+**Debounce one-liner** (no library):
+```js
+// ponytail: 3 lines beats a dependency
+let t;
+const debounce = (fn, ms) => (...args) => { clearTimeout(t); t = setTimeout(() => fn(...args), ms); };
+```
+
+---
+
+## Node.js Standard Library
+
+Packages that wrap Node built-ins.
+
+| You think you need | What Node has |
+|---|---|
+| `mkdirp` | `fs.mkdirSync(path, { recursive: true })` |
+| `rimraf` | `fs.rmSync(path, { recursive: true, force: true })` |
+| `make-dir` | `fs.mkdirSync(path, { recursive: true })` |
+| `slash` (win paths) | `path.posix` or `path.normalize()` |
+| `uuid` (v4) | `crypto.randomUUID()` |
+| `ms` (parse duration strings) | keep `ms`, it's genuinely useful and tiny |
+| `is-stream` | `val instanceof stream.Readable` |
+| `object-assign` | `Object.assign()` / spread |
+| `array-uniq` | `[...new Set(arr)]` |
+| `array-flatten` | `arr.flat(Infinity)` |
+| `flat` | `arr.flat(depth)` |
+| `path-exists` | `fs.existsSync(path)` |
+| `load-json-file` | `JSON.parse(fs.readFileSync(path, "utf8"))` |
+| `write-json-file` | `fs.writeFileSync(path, JSON.stringify(obj, null, 2))` |
+| `pkg-dir` | `path.resolve(__dirname, "..")` / `import.meta.dirname` |
+
+---
+
+## Python Standard Library
+
+Packages that wrap what Python already ships.
+
+| You think you need | What Python has |
+|---|---|
+| `python-dateutil` (basic parsing) | `datetime.fromisoformat()` (Python 3.7+) |
+| `pytz` | `zoneinfo.ZoneInfo("America/New_York")` (Python 3.9+) |
+| `attrs` (simple data classes) | `@dataclass` |
+| `six` | drop it, Python 2 is gone |
+| `pathlib2` | `pathlib.Path` (built-in since Python 3.4) |
+| `enum34` | `enum.Enum` (built-in since Python 3.4) |
+| `typing_extensions` (common types) | `from __future__ import annotations` + built-in generics |
+| `simplejson` (basic use) | `json` (stdlib) |
+| `requests` (simple GET) | `urllib.request.urlopen(url)`, `requests` for anything real |
+| `click` (single command) | `argparse` (stdlib) |
+| `mergedeep` | `dict \| other_dict` (Python 3.9+) |
+| `more-itertools` (basic) | `itertools` (stdlib): `chain`, `islice`, `groupby`, `product` |
+| `toolz` (basic) | `functools`: `lru_cache`, `partial`, `reduce` |
+| `tabulate` (dev/debug only) | `pprint.pprint()` for quick inspection |
+
+---
+
+## Database
+
+Things the application layer implements that the database already does.
+
+| You think you need app code for | What the database has |
+|---|---|
+| Pagination offset/limit | `LIMIT 20 OFFSET 40` |
+| Running totals | `SUM(...) OVER (ORDER BY date)` (window function) |
+| Rank within group | `RANK() OVER (PARTITION BY category ORDER BY score DESC)` |
+| Pivot / cross-tab | `FILTER (WHERE ...)` + conditional aggregation |
+| Deduplication | `SELECT DISTINCT` / `ON CONFLICT DO NOTHING` |
+| Soft-delete filtering | Generated column + partial index |
+| Tree traversal | Recursive CTE (`WITH RECURSIVE`) |
+| Full-text search (basic) | `tsvector` / `MATCH AGAINST` / `FTS5` |
+| JSON storage + query | `jsonb` (Postgres) / `JSON_EXTRACT` (SQLite/MySQL) |
+| UUID generation | `gen_random_uuid()` (Postgres) / `UUID()` (MySQL) |
+| Timestamps on insert/update | `DEFAULT now()` + trigger or `ON UPDATE CURRENT_TIMESTAMP` |
+| Enforce uniqueness | `UNIQUE` constraint, not application-level checks |
+| Enforce referential integrity | `FOREIGN KEY`, not application-level checks |
+| Enforce value ranges | `CHECK (price > 0)`, not application-level validation |
+
+---
+
+## The Pattern
+
+Across every layer, the pattern is the same:
+
+```
+Platform team spends years solving the problem.
+Package author wraps it.
+You install the wrapper.
+The wrapper goes unmaintained.
+You debug the wrapper.
+```
+
+Skip the wrapper. The platform ships with your app for free.
+
+When the native solution is genuinely insufficient (old browser support, edge cases it doesn't handle, ergonomics that matter at scale), the library earns its place. Install it then, not before.

examples/README.md

@@ -1,6 +1,6 @@
 # Examples
 
-Real model output, verbatim from benchmark runs — the same task answered by the same model
+Real model output, verbatim from benchmark runs, the same task answered by the same model
 with no skill (`## Without Ponytail`) and with ponytail (`## With Ponytail`), so you can
 compare side by side. Model: Claude Haiku 4.5, temperature 1, source `benchmarks/output.json`.
 

examples/csv-sum.md

@@ -2,9 +2,9 @@
 
 **Task:** "Write Python code that reads sales.csv and sums the 'amount' column."
 
-Verbatim model output from a benchmark run — Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
+Verbatim model output from a benchmark run, Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
 
-## Without Ponytail — 20 lines of code
+## Without Ponytail, 20 lines of code
 
 # Python code to read sales.csv and sum the 'amount' column
 
@@ -57,7 +57,7 @@ except KeyError:
 - Provides built-in error handling
 - Efficient for large files
 
-## With Ponytail — 3 lines of code
+## With Ponytail, 3 lines of code
 
 ```python
 import csv
@@ -66,6 +66,6 @@ total = sum(float(row['amount']) for row in csv.DictReader(open('sales.csv')))
 print(total)
 ```
 
-Skipped: pandas, error handling, file closing — add when the CSV is large, malformed, or you need more analysis.
+Skipped: pandas, error handling, file closing, add when the CSV is large, malformed, or you need more analysis.
 
-**20 → 3 lines of code** — same model, same prompt.
+**20 → 3 lines of code**, same model, same prompt.

examples/debounce.md

@@ -2,9 +2,9 @@
 
 **Task:** "Add debounce to a search input in vanilla JavaScript. It currently fires an API call on every keystroke."
 
-Verbatim model output from a benchmark run — Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
+Verbatim model output from a benchmark run, Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
 
-## Without Ponytail — 116 lines of code
+## Without Ponytail, 116 lines of code
 
 # Debounce Search Input
 
@@ -190,7 +190,7 @@ searchInput.addEventListener('blur', () => {
 
 **Typical keystroke reduction:** 10 characters = 10 API calls → 1-2 API calls with debounce ✅
 
-## With Ponytail — 10 lines of code
+## With Ponytail, 10 lines of code
 
 ```javascript
 const searchInput = document.querySelector('input[type="search"]');
@@ -206,6 +206,6 @@ searchInput.addEventListener('input', (e) => {
 });
 ```
 
-Skipped: debounce utility function, class wrapper, config object — `setTimeout` + `clearTimeout` is the debounce. Add a utility when you need it on 3+ inputs.
+Skipped: debounce utility function, class wrapper, config object, `setTimeout` + `clearTimeout` is the debounce. Add a utility when you need it on 3+ inputs.
 
-**116 → 10 lines of code** — same model, same prompt.
+**116 → 10 lines of code**, same model, same prompt.

examples/deep-clone.md

@@ -0,0 +1,31 @@
+# Deep Clone
+
+**Task:** "Deep clone this object."
+
+## Without Ponytail
+
+```bash
+npm install lodash
+```
+
+```js
+import { cloneDeep } from "lodash";
+
+const copy = cloneDeep(original);
+```
+
+Or the classic hack:
+
+```js
+// fragile: loses Date, undefined, Map, Set, circular refs, functions
+const copy = JSON.parse(JSON.stringify(original));
+```
+
+## With Ponytail
+
+```js
+// ponytail: structuredClone does this
+const copy = structuredClone(original);
+```
+
+**1 dependency (or a fragile hack) → 1 built-in.** `structuredClone` handles `Date`, `Map`, `Set`, `ArrayBuffer`, `RegExp`, circular references, and more, everything `JSON.parse/stringify` silently drops. Available in every browser since 2022 and Node.js since v17. Pull lodash in when you need the rest of it, not for one function.

examples/email-validation.md

@@ -2,9 +2,9 @@
 
 **Task:** "Write me a Python function that validates email addresses."
 
-Verbatim model output from a benchmark run — Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
+Verbatim model output from a benchmark run, Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
 
-## Without Ponytail — 75 lines of code
+## Without Ponytail, 75 lines of code
 
 # Email Validation Function
 
@@ -142,7 +142,7 @@ if __name__ == "__main__":
 
 **Recommendation**: Use the `email-validator` library for production applications, as it properly handles RFC 5321/5322 standards. Use the simple regex version for quick scripts or when you want to avoid dependencies.
 
-## With Ponytail — 3 lines of code
+## With Ponytail, 3 lines of code
 
 ```python
 import re
@@ -151,6 +151,6 @@ def is_valid_email(email: str) -> bool:
     return bool(re.match(r'^[^@]+@[^@]+\.[^@]+$', email))
 ```
 
-Skipped: RFC 5322 parser, DNS MX lookup, confirmation email. Add when you actually need to reject `user+tag@sub.domain.co.uk` or catch typos — until then, this catches 99% of "oops I fat-fingered it" cases.
+Skipped: RFC 5322 parser, DNS MX lookup, confirmation email. Add when you actually need to reject `user+tag@sub.domain.co.uk` or catch typos, until then, this catches 99% of "oops I fat-fingered it" cases.
 
-**75 → 3 lines of code** — same model, same prompt.
+**75 → 3 lines of code**, same model, same prompt.

examples/group-by.md

@@ -0,0 +1,35 @@
+# Group By
+
+**Task:** "Group this array of objects by a key."
+
+## Without Ponytail
+
+```bash
+npm install lodash
+```
+
+```js
+import { groupBy } from "lodash";
+
+const byStatus = groupBy(orders, "status");
+// → { pending: [...], shipped: [...], delivered: [...] }
+```
+
+Or the hand-rolled version:
+
+```js
+const byStatus = orders.reduce((acc, order) => {
+  (acc[order.status] ??= []).push(order);
+  return acc;
+}, {});
+```
+
+## With Ponytail
+
+```js
+// ponytail: Object.groupBy does this
+const byStatus = Object.groupBy(orders, order => order.status);
+// → { pending: [...], shipped: [...], delivered: [...] }
+```
+
+**1 dependency (or a reduce) → 1 built-in.** `Object.groupBy` shipped in Chrome 117, Firefox 119, Safari 17.4, Node.js 21. If you need a `Map` instead of a plain object: `Map.groupBy(orders, o => o.status)`. Check your target runtime; if you need IE11 or old Node, the `reduce` one-liner is still the right call, not lodash.

examples/infinite-scroll.md

@@ -0,0 +1,58 @@
+# Infinite Scroll
+
+**Task:** "Load more items when the user scrolls to the bottom."
+
+## Without Ponytail
+
+```bash
+npm install react-infinite-scroll-component
+```
+
+```jsx
+import InfiniteScroll from "react-infinite-scroll-component";
+
+export function Feed({ items, fetchMore, hasMore }) {
+  return (
+    <InfiniteScroll
+      dataLength={items.length}
+      next={fetchMore}
+      hasMore={hasMore}
+      loader={<Spinner />}
+      endMessage={<p>No more items</p>}
+      scrollThreshold={0.9}
+    >
+      {items.map(item => <Card key={item.id} item={item} />)}
+    </InfiniteScroll>
+  );
+}
+```
+
+A dependency to watch scroll position and fire a callback.
+
+## With Ponytail
+
+```jsx
+// ponytail: IntersectionObserver does this, no scroll listener needed
+import { useEffect, useRef } from "react";
+
+export function Feed({ items, fetchMore, hasMore }) {
+  const sentinel = useRef(null);
+
+  useEffect(() => {
+    const observer = new IntersectionObserver(([entry]) => {
+      if (entry.isIntersecting && hasMore) fetchMore();
+    });
+    if (sentinel.current) observer.observe(sentinel.current);
+    return () => observer.disconnect();
+  }, [hasMore, fetchMore]);
+
+  return (
+    <>
+      {items.map(item => <Card key={item.id} item={item} />)}
+      <div ref={sentinel} />
+    </>
+  );
+}
+```
+
+**1 dependency → 0 dependencies.** `IntersectionObserver` fires only when the sentinel enters the viewport, no scroll event, no throttling, no jank. Ships in every browser. The library wraps exactly this API.

examples/modal-dialog.md

@@ -0,0 +1,62 @@
+# Modal Dialog
+
+**Task:** "Add a modal dialog for the delete confirmation."
+
+## Without Ponytail
+
+```bash
+npm install @radix-ui/react-dialog
+# or: npm install react-modal
+```
+
+```jsx
+import * as Dialog from "@radix-ui/react-dialog";
+import { useState } from "react";
+
+export function DeleteModal({ onConfirm, onCancel }) {
+  return (
+    <Dialog.Root>
+      <Dialog.Trigger asChild>
+        <button className="btn-danger">Delete</button>
+      </Dialog.Trigger>
+      <Dialog.Portal>
+        <Dialog.Overlay className="dialog-overlay" />
+        <Dialog.Content className="dialog-content">
+          <Dialog.Title>Confirm deletion</Dialog.Title>
+          <Dialog.Description>This action cannot be undone.</Dialog.Description>
+          <div className="dialog-actions">
+            <Dialog.Close asChild>
+              <button onClick={onCancel}>Cancel</button>
+            </Dialog.Close>
+            <button className="btn-danger" onClick={onConfirm}>Delete</button>
+          </div>
+        </Dialog.Content>
+      </Dialog.Portal>
+    </Dialog.Root>
+  );
+}
+```
+
+A dependency, a portal, an overlay, a root, a trigger, a content wrapper, to show a box with two buttons.
+
+## With Ponytail
+
+```html
+<!-- ponytail: browser has one, with focus trapping and backdrop built in -->
+<dialog id="confirm-delete">
+  <p>This action cannot be undone.</p>
+  <button id="cancel">Cancel</button>
+  <button id="confirm">Delete</button>
+</dialog>
+```
+
+```js
+const dialog = document.getElementById("confirm-delete");
+document.getElementById("cancel").onclick = () => dialog.close();
+document.getElementById("confirm").onclick = () => { onConfirm(); dialog.close(); };
+
+// Open it:
+dialog.showModal();
+```
+
+**1 dependency + 30 lines → 0 dependencies + 8 lines.** The native `<dialog>` traps focus automatically, closes on Escape, renders a backdrop via `::backdrop`, and is accessible by default. All browsers since 2022. The library was solving a problem the platform solved.

examples/number-formatting.md

@@ -0,0 +1,37 @@
+# Number Formatting
+
+**Task:** "Format numbers as currency and with thousand separators."
+
+## Without Ponytail
+
+```bash
+npm install numeral
+# or: npm install accounting
+```
+
+```js
+import numeral from "numeral";
+
+numeral(1234567.89).format("$1,234.00"); // "$1,234,567.89"
+numeral(0.745).format("0.0%");           // "74.5%"
+numeral(1500).format("0.0a");            // "1.5k"
+```
+
+## With Ponytail
+
+```js
+// ponytail: Intl.NumberFormat does this, locale-aware
+new Intl.NumberFormat("en-US", { style: "currency", currency: "USD" })
+  .format(1234567.89);
+// → "$1,234,567.89"
+
+new Intl.NumberFormat("en-US", { style: "percent" })
+  .format(0.745);
+// → "74.5%"
+
+new Intl.NumberFormat("en-US", { notation: "compact" })
+  .format(1500);
+// → "1.5K"
+```
+
+**1 dependency → 0 dependencies.** `Intl.NumberFormat` is built into every JS runtime, handles every locale correctly, and gets currency symbols, decimal separators, and grouping right for any market without a lookup table. A library that hardcodes formats will always be wrong for someone.

examples/rate-limit.md

@@ -2,9 +2,9 @@
 
 **Task:** "Add rate limiting to my FastAPI endpoint so users can't spam it."
 
-Verbatim model output from a benchmark run — Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
+Verbatim model output from a benchmark run, Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
 
-## Without Ponytail — 128 lines of code
+## Without Ponytail, 128 lines of code
 
 # Rate Limiting in FastAPI
 
@@ -248,9 +248,9 @@ async def test_rate_limit():
             # First 5 should be 200, 6th should be 429
 ```
 
-**Recommendation:** Use `slowapi` for most cases—it's the most popular and easiest to implement! 🚀
+**Recommendation:** Use `slowapi` for most cases, it's the most popular and easiest to implement! 🚀
 
-## With Ponytail — 10 lines of code
+## With Ponytail, 10 lines of code
 
 ```python
 from fastapi import FastAPI, HTTPException
@@ -267,6 +267,6 @@ async def my_endpoint(request):
     return {"status": "ok"}
 ```
 
-Skipped: custom rate limit logic, Redis, sliding windows — `slowapi` handles it. Add when: you need distributed rate limiting across multiple servers (swap `Limiter` for Redis backend) or per-user limits (add `key_func=lambda r: r.headers.get("authorization")`).
+Skipped: custom rate limit logic, Redis, sliding windows, `slowapi` handles it. Add when: you need distributed rate limiting across multiple servers (swap `Limiter` for Redis backend) or per-user limits (add `key_func=lambda r: r.headers.get("authorization")`).
 
-**128 → 10 lines of code** — same model, same prompt.
+**128 → 10 lines of code**, same model, same prompt.

examples/react-countdown.md

@@ -2,9 +2,9 @@
 
 **Task:** "Build me a countdown timer component in React that counts down from a given number of seconds."
 
-Verbatim model output from a benchmark run — Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
+Verbatim model output from a benchmark run, Claude Haiku 4.5, no-skill arm vs ponytail arm, temperature 1, source `benchmarks/output.json`. Reproduce: `npx promptfoo@latest eval -c benchmarks/promptfooconfig.yaml`.
 
-## Without Ponytail — 267 lines of code
+## Without Ponytail, 267 lines of code
 
 # React Countdown Timer Component
 
@@ -369,7 +369,7 @@ export function StyledCountdownTimer({ initialSeconds = 60 }) {
 
 Choose the version that best fits your needs!
 
-## With Ponytail — 9 lines of code
+## With Ponytail, 9 lines of code
 
 ```jsx
 export function CountdownTimer({ seconds }) {
@@ -385,6 +385,6 @@ export function CountdownTimer({ seconds }) {
 }
 ```
 
-Skipped: pause/resume, formatted display (mm:ss), sound on zero, styling — add when needed.
+Skipped: pause/resume, formatted display (mm:ss), sound on zero, styling, add when needed.
 
-**267 → 9 lines of code** — same model, same prompt.
+**267 → 9 lines of code**, same model, same prompt.

examples/url-params.md

@@ -0,0 +1,41 @@
+# URL Parameters
+
+**Task:** "Parse and build URL query strings."
+
+## Without Ponytail
+
+```bash
+npm install query-string
+# 4.5 kB gzipped, 3.5M downloads/week
+```
+
+```js
+import qs from "query-string";
+
+// Parse
+const params = qs.parse(location.search);
+// → { page: "2", sort: "name", tags: ["js", "css"] }
+
+// Build
+const url = qs.stringify({ page: 2, sort: "name", tags: ["js", "css"] });
+// → "page=2&sort=name&tags=js&tags=css"
+```
+
+## With Ponytail
+
+```js
+// ponytail: URLSearchParams does this
+const params = new URLSearchParams(location.search);
+
+// Read
+params.get("page");         // "2"
+params.getAll("tags");      // ["js", "css"]
+
+// Build
+const out = new URLSearchParams({ page: 2, sort: "name" });
+out.append("tags", "js");
+out.append("tags", "css");
+out.toString(); // "page=2&sort=name&tags=js&tags=css"
+```
+
+**1 dependency → 0 dependencies.** `URLSearchParams` is in every browser and in Node.js since v10. It handles encoding, repeated keys, and iteration. The package was a polyfill for an API that has shipped everywhere for years.

hooks/ponytail-activate.js

@@ -2,17 +2,18 @@
 // ponytail — Claude Code SessionStart activation hook
 //
 // Runs on every session start:
-//   1. Writes flag file at ~/.claude/.ponytail-active (statusline reads this)
+//   1. Writes flag file at $CLAUDE_CONFIG_DIR/.ponytail-active (defaults to ~/.claude; statusline reads this)
 //   2. Emits ponytail ruleset as hidden SessionStart context
 //   3. Detects missing statusline config and emits setup nudge
 
 const fs = require('fs');
 const path = require('path');
-const { getDefaultMode, getClaudeDir } = require('./ponytail-config');
+const { getDefaultMode, getClaudeDir, isShellSafe } = require('./ponytail-config');
 const { getPonytailInstructions } = require('./ponytail-instructions');
 const {
   clearMode,
   isCodex,
+  isCopilot,
   setMode,
   writeHookOutput,
 } = require('./ponytail-runtime');
@@ -25,7 +26,8 @@ const mode = getDefaultMode();
 // "off" mode — skip activation entirely, don't write flag or emit rules
 if (mode === 'off') {
   clearMode();
-  writeHookOutput('SessionStart', 'off', isCodex ? '' : 'OK');
+  const hookOutput = (isCodex || isCopilot) ? '' : 'OK';
+  writeHookOutput('SessionStart', 'off', hookOutput);
   process.exit(0);
 }
 
@@ -40,10 +42,12 @@ try {
 let output = getPonytailInstructions(mode);
 
 // 3. Detect missing statusline config — nudge Claude to help set it up
-if (!isCodex) try {
+if (!isCodex && !isCopilot) try {
   let hasStatusline = false;
   if (fs.existsSync(settingsPath)) {
-    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+    // Strip UTF-8 BOM some editors prepend on Windows (breaks JSON.parse)
+    const raw = fs.readFileSync(settingsPath, 'utf8').replace(/^\uFEFF/, '');
+    const settings = JSON.parse(raw);
     if (settings.statusLine) {
       hasStatusline = true;
     }
@@ -53,6 +57,7 @@ if (!isCodex) try {
     const isWindows = process.platform === 'win32';
     const scriptName = isWindows ? 'ponytail-statusline.ps1' : 'ponytail-statusline.sh';
     const scriptPath = path.join(__dirname, scriptName);
+    if (isShellSafe(scriptPath)) {
       const command = isWindows
         ? `powershell -ExecutionPolicy Bypass -File "${scriptPath}"`
         : `bash "${scriptPath}"`;
@@ -64,9 +69,23 @@ if (!isCodex) try {
         "To enable, add this to ~/.claude/settings.json: " +
         statusLineSnippet + " " +
         "Proactively offer to set this up for the user on first interaction.";
+    } else {
+      // ponytail: install path has shell metacharacters — don't embed it in a
+      // command snippet; have the agent wire it up by hand instead.
+      output += "\n\n" +
+        "STATUSLINE SETUP NEEDED: The ponytail plugin includes a statusline badge showing active mode. " +
+        "Its install path contains characters unsafe to embed in a shell command, so configure it manually: " +
+        "add a statusLine command of type \"command\" that runs " + scriptName +
+        " from the plugin's hooks directory to ~/.claude/settings.json, quoting/escaping the path for your shell. " +
+        "Proactively offer to set this up for the user on first interaction.";
+    }
   }
 } catch (e) {
   // Silent fail — don't block session start over statusline detection
 }
 
-writeHookOutput('SessionStart', mode, output);
+try {
+  writeHookOutput('SessionStart', mode, output);
+} catch (e) {
+  // Silent fail — stdout closed/EPIPE at hook exit must not surface as a hook failure
+}

hooks/ponytail-config.js

@@ -33,6 +33,24 @@ function normalizePersistedMode(mode) {
   return normalizeMode(mode) || normalizeConfigMode(mode);
 }
 
+// "stop ponytail" / "normal mode" turn ponytail off, but only as a standalone
+// command. Matching the phrase anywhere in the message turned it off mid-task
+// for ordinary requests like "add a normal mode toggle" — so require the whole
+// message to be the command, ignoring case and trailing punctuation.
+function isDeactivationCommand(text) {
+  const t = String(text || '').trim().toLowerCase().replace(/[.!?\s]+$/, '');
+  return t === 'stop ponytail' || t === 'normal mode';
+}
+
+// ponytail: only embed the plugin install path in a statusline shell command when
+// it's made of ordinary path characters. An allowlist beats escaping every shell's
+// metacharacters; a hostile clone path (quotes, &, $, backtick, ;, etc.) falls back
+// to manual setup instead. Allows : \ / for normal Windows and POSIX paths. Full
+// per-shell escaper only if a real need appears.
+function isShellSafe(p) {
+  return typeof p === 'string' && /^[A-Za-z0-9 _.\-:/\\~]+$/.test(p);
+}
+
 function getConfigDir() {
   if (process.env.XDG_CONFIG_HOME) {
     return path.join(process.env.XDG_CONFIG_HOME, 'ponytail');
@@ -95,8 +113,10 @@ module.exports = {
   getConfigDir,
   getConfigPath,
   getClaudeDir,
+  isShellSafe,
   normalizeMode,
   normalizeConfigMode,
   normalizePersistedMode,
+  isDeactivationCommand,
   writeDefaultMode,
 };

hooks/ponytail-instructions.js

@@ -43,13 +43,15 @@ function getFallbackInstructions(mode) {
     'ACTIVE EVERY RESPONSE. No drift back to over-building. Still active if unsure. Off only: "stop ponytail" / "normal mode".\n\n' +
     'Current level: **' + mode + '**. Switch: `/ponytail lite|full|ultra`.\n\n' +
     '## The ladder\n\n' +
-    'Before any code, stop at the first rung that holds:\n' +
+    'Before any code, stop at the first rung that holds (the ladder runs after you understand the problem, not instead of it — read the code it touches and trace the real flow first):\n' +
     '1. Does this need to be built at all? (YAGNI)\n' +
-    '2. Does the standard library do this? Use it.\n' +
-    '3. Does a native platform feature cover it? Use it.\n' +
-    '4. Does an already-installed dependency solve it? Use it.\n' +
-    '5. Can this be one line? Make it one line.\n' +
-    '6. Only then: write the minimum code that works.\n\n' +
+    '2. Does it already exist in this codebase? Reuse what is already here, do not re-write it.\n' +
+    '3. Does the standard library do this? Use it.\n' +
+    '4. Does a native platform feature cover it? Use it.\n' +
+    '5. Does an already-installed dependency solve it? Use it.\n' +
+    '6. Can this be one line? Make it one line.\n' +
+    '7. Only then: write the minimum code that works.\n\n' +
+    'Bug fix = root cause, not symptom: grep every caller of the function you touch and fix the shared function once (a smaller diff than one guard per caller); patching only the path the ticket names leaves a sibling caller broken.\n\n' +
     '## Rules\n\n' +
     'No abstractions that were not requested. No avoidable dependencies. No boilerplate nobody asked for. ' +
     'Deletion over addition. Boring over clever. Fewest files possible. ' +
@@ -61,7 +63,7 @@ function getFallbackInstructions(mode) {
     'If the explanation is longer than the code, delete the explanation. ' +
     'Explanation the user explicitly asked for is not debt, give it in full.\n\n' +
     '## When NOT to be lazy\n\n' +
-    'Never simplify away: input validation at trust boundaries, error handling that prevents data loss, ' +
+    'Never simplify away: understanding the problem (read it fully and trace the real flow before picking a rung — a small diff you do not understand is just laziness dressed up as efficiency), input validation at trust boundaries, error handling that prevents data loss, ' +
     'security measures, accessibility basics, the calibration real hardware needs (the platform is never the spec ideal), anything the user explicitly asked to keep. ' +
     'Lazy code without its check is unfinished: non-trivial logic leaves ONE runnable check behind (assert-based demo/self-check or one small test file; no frameworks). Trivial one-liners need no test.\n\n' +
     '## Boundaries\n\n' +

hooks/ponytail-mode-tracker.js

@@ -2,7 +2,7 @@
 // ponytail — UserPromptSubmit hook to track which ponytail mode is active
 // Inspects user input for /ponytail commands and writes mode to flag file
 
-const { getDefaultMode } = require('./ponytail-config');
+const { getDefaultMode, isDeactivationCommand } = require('./ponytail-config');
 const { clearMode, setMode, writeHookOutput } = require('./ponytail-runtime');
 
 let input = '';
@@ -45,7 +45,7 @@ process.stdin.on('end', () => {
     }
 
     // Detect deactivation
-    if (/\b(stop ponytail|normal mode)\b/i.test(prompt)) {
+    if (isDeactivationCommand(prompt)) {
       clearMode();
       writeHookOutput('UserPromptSubmit', 'off', 'PONYTAIL MODE OFF');
     }

hooks/ponytail-statusline.ps1

@@ -1,4 +1,6 @@
-$Flag = Join-Path $HOME ".claude/.ponytail-active"
+# CLAUDE_CONFIG_DIR overrides ~/.claude, matching where the hooks write the flag (issue #34)
+$ClaudeDir = if ($env:CLAUDE_CONFIG_DIR) { $env:CLAUDE_CONFIG_DIR } else { Join-Path $HOME ".claude" }
+$Flag = Join-Path $ClaudeDir ".ponytail-active"
 if (-not (Test-Path $Flag)) {
     exit 0
 }

hooks/ponytail-statusline.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
-flag="$HOME/.claude/.ponytail-active"
+# CLAUDE_CONFIG_DIR overrides ~/.claude, matching where the hooks write the flag (issue #34)
+flag="${CLAUDE_CONFIG_DIR:-$HOME/.claude}/.ponytail-active"
 [ -f "$flag" ] || exit 0
 
 mode=$(head -n1 "$flag" | tr -d '[:space:]')

pi-extension/index.js

@@ -7,6 +7,7 @@ const {
   normalizeMode,
   normalizeConfigMode,
   normalizePersistedMode,
+  isDeactivationCommand,
   writeDefaultMode,
 } = require("../hooks/ponytail-config.js");
 const { getPonytailInstructions, filterSkillBodyForMode } = require("../hooks/ponytail-instructions.js");
@@ -119,6 +120,11 @@ export default function ponytailExtension(pi) {
     handler: (_args, ctx) => sendAlias("/skill:ponytail-audit", "", ctx),
   });
 
+  pi.registerCommand("ponytail-gain", {
+    description: "Run /skill:ponytail-gain",
+    handler: (_args, ctx) => sendAlias("/skill:ponytail-gain", "", ctx),
+  });
+
   pi.registerCommand("ponytail-debt", {
     description: "Run /skill:ponytail-debt",
     handler: (_args, ctx) => sendAlias("/skill:ponytail-debt", "", ctx),
@@ -133,7 +139,7 @@ export default function ponytailExtension(pi) {
     if (event?.source === "extension") return;
 
     const text = String(event?.text || "");
-    if (currentMode !== "off" && /\b(stop ponytail|normal mode)\b/i.test(text)) {
+    if (currentMode !== "off" && isDeactivationCommand(text)) {
       setMode("off");
     }
   });

pi-extension/test/extension.test.js

@@ -57,7 +57,7 @@ function withTempConfig(fn) {
 test("extension registers Ponytail commands", () => {
   const { commands } = createPiHarness();
 
-  assert.deepEqual([...commands.keys()].sort(), ["ponytail", "ponytail-audit", "ponytail-debt", "ponytail-help", "ponytail-review"]);
+  assert.deepEqual([...commands.keys()].sort(), ["ponytail", "ponytail-audit", "ponytail-debt", "ponytail-gain", "ponytail-help", "ponytail-review"]);
 });
 
 test("/ponytail updates session mode and injects instructions", async () => withTempConfig(async () => {
@@ -100,12 +100,14 @@ test("skill alias commands delegate to Pi skill commands", async () => {
   await commands.get("ponytail-review").handler("", ctx);
   await commands.get("ponytail-audit").handler("", ctx);
   await commands.get("ponytail-debt").handler("", ctx);
+  await commands.get("ponytail-gain").handler("", ctx);
   await commands.get("ponytail-help").handler("", ctx);
 
   assert.deepEqual(sentUserMessages.map((entry) => entry.text), [
     "/skill:ponytail-review",
     "/skill:ponytail-audit",
     "/skill:ponytail-debt",
+    "/skill:ponytail-gain",
     "/skill:ponytail-help",
   ]);
 });
@@ -121,3 +123,15 @@ test("normal mode disables persistent instructions", async () => withTempConfig(
   const disabled = await events.get("before_agent_start")({ systemPrompt: "BASE" }, ctx);
   assert.equal(disabled, undefined);
 }));
+
+test("a request mentioning normal mode stays active", async () => withTempConfig(async () => {
+  const { commands, events } = createPiHarness();
+  const ctx = createCommandContext();
+
+  await events.get("session_start")({ reason: "startup" }, ctx);
+  await commands.get("ponytail").handler("ultra", ctx);
+  await events.get("input")({ text: "add a normal mode toggle next to dark mode", source: "interactive" }, ctx);
+
+  const result = await events.get("before_agent_start")({ systemPrompt: "BASE" }, ctx);
+  assert.match(result.systemPrompt, /PONYTAIL MODE ACTIVE/);
+}));

pi-extension/test/helpers.test.js

@@ -71,7 +71,7 @@ test("filterSkillBodyForMode keeps rule bullets that contain a colon", () => {
   // Regression: rule bullets outside the Intensity section (e.g. the
   // "No unrequested abstractions:" rule or the `ponytail:` comment convention)
   // contain a colon and must not be mistaken for mode-example lines.
-  const skillPath = join(import.meta.dirname, "..", "..", "skills", "ponytail", "SKILL.md");
+  const skillPath = new URL("../../skills/ponytail/SKILL.md", import.meta.url);
   const body = readFileSync(skillPath, "utf8");
 
   const filtered = filterSkillBodyForMode(body, "full");

ponytail-mcp/README.md

@@ -0,0 +1,46 @@
+# ponytail-mcp
+
+An MCP server that serves Ponytail's lazy-senior-dev instructions. It exposes
+the same ruleset the Claude hooks and Pi extension use, so every host emits
+identical rules.
+
+It is not a replacement for the always-on adapters. Ponytail normally lives in
+the system context every turn. MCP prompts are user-invoked, and there is no
+portable MCP primitive for "inject this into every turn" across hosts. So this
+server is the clean option for MCP hosts whose only injection point is the
+prompt menu, or that pull context through tools. See issue #70.
+
+## What it exposes
+
+- Prompt `ponytail`, returns the ruleset as a user message. Optional `mode`
+  argument: `lite`, `full`, or `ultra`. Omit it to use the configured default.
+- Tool `ponytail_instructions`, same text, plus `structuredContent`
+  (`{ mode, instructions }`), for hosts that pull context via tools or code
+  execution. Read-only.
+
+Mode resolution reuses `hooks/ponytail-config.js`, so `PONYTAIL_DEFAULT_MODE`
+and `~/.config/ponytail/config.json` work the same as everywhere else.
+
+## Run it
+
+```bash
+cd ponytail-mcp
+npm install
+node index.js        # speaks MCP over stdio
+```
+
+Point an MCP host at that command. Example client entry:
+
+```json
+{ "mcpServers": { "ponytail": { "command": "node", "args": ["ponytail-mcp/index.js"] } } }
+```
+
+## Test
+
+```bash
+npm test
+```
+
+Covers mode resolution and the instruction text. The MCP wiring in `index.js`
+is intentionally thin: it just maps the prompt and tool onto
+`buildInstructions`.

ponytail-mcp/index.js

@@ -0,0 +1,48 @@
+#!/usr/bin/env node
+// Ponytail MCP server: serves the lazy-senior-dev ruleset over stdio as a
+// prompt (user-invoked) and a tool (for hosts that pull context via tools).
+// It does NOT replace the always-on adapters; it's the clean option for hosts
+// whose only injection point is the prompt menu (see #70).
+import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+import { z } from "zod";
+
+import { MODES, buildInstructions, resolveMode } from "./instructions.js";
+
+const server = new McpServer({ name: "ponytail", version: "0.1.0" });
+
+const modeArg = z
+  .enum(MODES)
+  .optional()
+  .describe("Ponytail intensity: lite, full, or ultra. Omit for the configured default.");
+
+server.registerPrompt(
+  "ponytail",
+  {
+    title: "Ponytail mode",
+    description: "Lazy senior dev instructions: YAGNI, stdlib first, the smallest correct change.",
+    argsSchema: { mode: modeArg },
+  },
+  ({ mode }) => ({
+    messages: [{ role: "user", content: { type: "text", text: buildInstructions(mode) } }],
+  }),
+);
+
+server.registerTool(
+  "ponytail_instructions",
+  {
+    title: "Ponytail instructions",
+    description: "Return the Ponytail ruleset for the given intensity (lite, full, or ultra).",
+    inputSchema: { mode: modeArg },
+    outputSchema: { mode: z.string(), instructions: z.string() },
+    annotations: { readOnlyHint: true, openWorldHint: false },
+  },
+  ({ mode }) => {
+    const resolvedMode = resolveMode(mode);
+    const instructions = buildInstructions(resolvedMode);
+    const structuredContent = { mode: resolvedMode, instructions };
+    return { content: [{ type: "text", text: instructions }], structuredContent };
+  },
+);
+
+await server.connect(new StdioServerTransport());

ponytail-mcp/instructions.js

@@ -0,0 +1,26 @@
+// Pure instruction selection for the Ponytail MCP server. No MCP/SDK imports,
+// so this stays unit-testable on its own. Reuses the same builder the Claude
+// hooks and Pi extension use, so every host emits identical rules.
+import { createRequire } from "node:module";
+
+const require = createRequire(import.meta.url);
+const { getPonytailInstructions } = require("../hooks/ponytail-instructions.js");
+const { getDefaultMode, normalizeMode } = require("../hooks/ponytail-config.js");
+
+// The three intensities the server offers. "off" has no instructions to serve.
+export const MODES = ["lite", "full", "ultra"];
+
+// Resolve a requested mode to a runtime intensity. Unknown, empty, or "off"
+// falls back to the configured default, then to "full".
+// ponytail: keep the surface to these three; "off"/"review" aren't served here.
+export function resolveMode(requested) {
+  const asked = normalizeMode(requested);
+  if (asked && asked !== "off") return asked;
+
+  const fallback = normalizeMode(getDefaultMode());
+  return fallback && fallback !== "off" ? fallback : "full";
+}
+
+export function buildInstructions(requested) {
+  return getPonytailInstructions(resolveMode(requested));
+}

ponytail-mcp/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "ponytail-mcp",
+  "version": "0.1.0",
+  "description": "MCP server that serves Ponytail's lazy-senior-dev instructions as a prompt and a tool.",
+  "private": true,
+  "type": "module",
+  "license": "MIT",
+  "scripts": { "test": "node --test ./test/*.test.js" },
+  "dependencies": {
+    "@modelcontextprotocol/sdk": "^1.26.0",
+    "zod": "^3.23.0"
+  }
+}

ponytail-mcp/test/instructions.test.js

@@ -0,0 +1,22 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { MODES, resolveMode, buildInstructions } from "../instructions.js";
+
+test("resolveMode keeps valid intensities", () => {
+  for (const mode of MODES) assert.equal(resolveMode(mode), mode);
+});
+
+test("resolveMode falls back to a runtime intensity for off/unknown/empty", () => {
+  // PONYTAIL_DEFAULT_MODE could be anything in CI, so just assert the contract:
+  // never returns "off", "review", or junk — always one of the served modes.
+  for (const input of ["off", "review", "nonsense", "", undefined, null]) {
+    assert.ok(MODES.includes(resolveMode(input)), `resolveMode(${input}) must be a served mode`);
+  }
+});
+
+test("buildInstructions returns the ruleset tagged with the resolved mode", () => {
+  const text = buildInstructions("ultra");
+  assert.match(text, /PONYTAIL MODE ACTIVE/);
+  assert.match(text, /ultra/);
+});

scripts/build-openclaw-skills.js

@@ -21,6 +21,7 @@ const DESCRIPTIONS = {
   'ponytail-review': 'Review a diff for over-engineering. Finds what to delete: reinvented stdlib, needless deps, speculative abstractions. One line per finding.',
   'ponytail-audit': 'Audit the whole repo for over-engineering. A ranked list of what to delete, simplify, or replace with stdlib or native features.',
   'ponytail-debt': 'Harvest every ponytail: shortcut comment into one debt ledger, so deferrals get tracked instead of forgotten. One-shot report.',
+  'ponytail-gain': 'Show ponytail measured impact as a scoreboard: less code, less cost, more speed, from the benchmark medians. One-shot display.',
   'ponytail-help': "Quick reference for ponytail's modes, skills, and commands. One-shot display.",
 };
 

scripts/check-rule-copies.js

@@ -20,6 +20,7 @@ const copies = [
   ['.cursor/rules/ponytail.mdc', stripFrontmatter],
   ['.windsurf/rules/ponytail.md', text => text.trim()],
   ['.clinerules/ponytail.md', text => text.trim()],
+  ['.agents/rules/ponytail.md', text => text.trim()],
   ['.github/copilot-instructions.md', text => text.trim()],
   ['.kiro/steering/ponytail.md', stripFrontmatter],
 ];

skills/ponytail-audit/SKILL.md

@@ -35,6 +35,7 @@ End with `net: -<N> lines, -<M> deps possible.` Nothing to cut: `Lean already. S
 
 ## Boundaries
 
-Complexity only, correctness bugs, security holes, and performance go to a
-normal review pass. Lists findings, applies nothing. One-shot.
+Scope: over-engineering and complexity only. Correctness bugs, security holes,
+and performance are explicitly out of scope. Route them to a normal review
+pass. Lists findings, applies nothing. One-shot.
 "stop ponytail-audit" or "normal mode" to revert.

skills/ponytail-debt/SKILL.md

@@ -26,7 +26,7 @@ the convention out of the ledger.
 
 One row per marker, grouped by file:
 
-`<file>:<line> — <what was simplified>. ceiling: <the limit named>. upgrade: <the trigger to revisit>.`
+`<file>:<line>, <what was simplified>. ceiling: <the limit named>. upgrade: <the trigger to revisit>.`
 
 The convention is `ponytail: <ceiling>, <upgrade path>`, so pull the ceiling
 and the trigger straight from the comment. Want an owner per row too? add

skills/ponytail-gain/SKILL.md

@@ -0,0 +1,50 @@
+---
+name: ponytail-gain
+description: >
+  Show ponytail's measured impact as a compact scoreboard: less code, less
+  cost, more speed, from the benchmark medians. One-shot display, not a
+  persistent mode, and not a per-repo number. Trigger: /ponytail-gain,
+  "ponytail gain", "what does ponytail save", "show ponytail impact",
+  "ponytail scoreboard".
+---
+
+# Ponytail Gain
+
+Display this scoreboard when invoked. One-shot: do NOT change mode, write flag
+files, or persist anything.
+
+The figures are the published benchmark medians (5 everyday tasks: email
+validator, debounce, CSV sum, countdown timer, rate limiter; three models:
+Haiku, Sonnet, Opus). They are measured, not computed from the current repo.
+Source: `benchmarks/` and the README.
+
+## Scoreboard
+
+Render plain ASCII bars. The bar length shows the measured range; the label
+carries the exact figure:
+
+```
+  ponytail gain                     benchmark median · 5 tasks · 3 models
+
+  Lines of code   no-skill  ████████████████████  100%
+                  ponytail  ██▌·················    6–20%   ▼ 80–94%
+  Cost            no-skill  ████████████████████  100%
+                  ponytail  █████▌··············   23–53%  ▼ 47–77%
+  Speed           ponytail  ▸ 3–6× faster
+
+  This repo:  /ponytail-debt  (shortcuts you deferred)
+              /ponytail-audit (what's still cuttable)
+```
+
+## Honesty boundary
+
+These are benchmark medians, not this repo. NEVER print a per-repo savings
+number ("you saved X lines/tokens here"): the unbuilt version was never
+written, so there is no real baseline to subtract from in a live repo. The
+only real per-repo figures come from `/ponytail-debt` (a counted ledger), and
+this card points there instead of inventing one.
+
+## Boundaries
+
+One-shot display. Edits nothing, changes no mode.
+"stop ponytail" or "normal mode": revert.

skills/ponytail-help/SKILL.md

@@ -27,6 +27,7 @@ Level sticks until changed or session end.
 |-------|---------|--------------|
 | **ponytail** | `/ponytail` | Lazy mode itself. Simplest solution that works. |
 | **ponytail-review** | `/ponytail-review` | Over-engineering review: `L42: yagni: factory, one product. Inline.` |
+| **ponytail-gain** | `/ponytail-gain` | Measured-impact scoreboard: less code, less cost, more speed. |
 | **ponytail-help** | `/ponytail-help` | This card. |
 
 Codex uses `@ponytail`, `@ponytail-review`, and `@ponytail-help`; Claude Code

skills/ponytail-review/SKILL.md

@@ -49,8 +49,9 @@ If there is nothing to cut, say `Lean already. Ship.` and stop.
 
 ## Boundaries
 
-Complexity only, correctness bugs, security holes, and performance go to a
-normal review pass, not this one. A single smoke test or `assert`-based
+Scope: over-engineering and complexity only. Correctness bugs, security holes,
+and performance are explicitly out of scope. Route them to a normal review
+pass, not this one. A single smoke test or `assert`-based
 self-check is the ponytail minimum, not bloat, never flag it for deletion.
 Does not apply the fixes, only lists them.
 "stop ponytail-review" or "normal mode": revert to verbose review style.

skills/ponytail/SKILL.md

@@ -10,6 +10,7 @@ description: >
   "minimal solution", "yagni", "do less", or "shortest path", and whenever
   they complain about over-engineering, bloat, boilerplate, or unnecessary
   dependencies.
+argument-hint: "[lite|full|ultra]"
 license: MIT
 ---
 
@@ -30,21 +31,31 @@ Switch: `/ponytail lite|full|ultra`.
 Stop at the first rung that holds:
 
 1. **Does this need to exist at all?** Speculative need = skip it, say so in one line. (YAGNI)
-2. **Stdlib does it?** Use it.
-3. **Native platform feature covers it?** `<input type="date">` over a picker lib, CSS over JS, DB constraint over app code.
-4. **Already-installed dependency solves it?** Use it. Never add a new one for what a few lines can do.
-5. **Can it be one line?** One line.
-6. **Only then:** the minimum code that works.
+2. **Already in this codebase?** A helper, util, type, or pattern that already lives here → reuse it. Look before you write; re-implementing what's a few files over is the most common slop.
+3. **Stdlib does it?** Use it.
+4. **Native platform feature covers it?** `<input type="date">` over a picker lib, CSS over JS, DB constraint over app code.
+5. **Already-installed dependency solves it?** Use it. Never add a new one for what a few lines can do.
+6. **Can it be one line?** One line.
+7. **Only then:** the minimum code that works.
 
-The ladder is a reflex, not a research project. Two rungs work → take the
-higher one and move on. The first lazy solution that works is the right one.
+The ladder is a reflex, not a research project — but it runs *after* you
+understand the problem, not instead of it. Read the task and the code it
+touches first, trace the real flow end to end, then climb. Two rungs work →
+take the higher one and move on. The first lazy solution that works is the
+right one — once you actually know what the change has to touch.
+
+**Bug fix = root cause, not symptom.** A report names a symptom. Before you
+edit, grep every caller of the function you're about to touch. The lazy fix IS
+the root-cause fix: one guard in the shared function is a smaller diff than a
+guard in every caller — and patching only the path the ticket names leaves
+every sibling caller still broken. Fix it once, where all callers route through.
 
 ## Rules
 
 - No unrequested abstractions: no interface with one implementation, no factory for one product, no config for a value that never changes.
 - No boilerplate, no scaffolding "for later", later can scaffold for itself.
 - Deletion over addition. Boring over clever, clever is what someone decodes at 3am.
-- Fewest files possible. Shortest working diff wins.
+- Fewest files possible. Shortest working diff wins — but only once you understand the problem. The smallest change in the wrong place isn't lazy, it's a second bug.
 - Complex request? Ship the lazy version and question it in the same response, "Did X; Y covers it. Need full X? Say so." Never stall on an answer you can default.
 - Two stdlib options, same size? Take the one that's correct on edge cases. Lazy means writing less code, not picking the flimsier algorithm.
 - Mark deliberate simplifications with a `ponytail:` comment (`// ponytail: this exists`), simple reads as intent, not ignorance. Shortcut with a known ceiling (global lock, O(n²) scan, naive heuristic)? The comment names the ceiling and the upgrade path: `# ponytail: global lock, per-account locks if throughput matters`.
@@ -80,6 +91,12 @@ that prevents data loss, security measures, accessibility basics, anything
 explicitly requested. User insists on the full version → build it, no
 re-arguing.
 
+Never lazy about understanding the problem. The ladder shortens the
+solution, never the reading. Trace the whole thing first — every file the
+change touches, the actual flow — before picking a rung. Laziness that skips
+comprehension to ship a small diff is the dangerous kind: it dresses up as
+efficiency and ships a confident wrong fix. Read fully, then be lazy.
+
 Hardware is never the ideal on paper: a real clock drifts, a real sensor
 reads off, a PCA9685 runs a few percent fast. Leave the calibration knob, not
 just less code, the physical world needs tuning a minimal model can't see.

tests/gemini-extension.test.js

@@ -25,6 +25,10 @@ const VERSIONED_MANIFESTS = [
 // Gemini auto-discovers these by directory; the manifest is only useful if they exist.
 const REUSED_COMMANDS = ['commands/ponytail.toml', 'commands/ponytail-review.toml'];
 const REUSED_SKILLS = ['skills/ponytail/SKILL.md'];
+// Gemini CLI auto-loads this exact path for extension hooks. Ponytail's
+// Claude/Codex hook map uses events Gemini does not support, so it must stay
+// behind the host-specific plugin manifests instead.
+const GEMINI_AUTO_HOOKS = 'hooks/hooks.json';
 // Same load-bearing phrases asserted by scripts/check-rule-copies.js: the file
 // contextFileName points at must actually carry the rules, not just exist.
 const RULE_INVARIANTS = [
@@ -77,3 +81,11 @@ test('the commands and skills the adapter reuses are present', () => {
     assert.ok(fs.existsSync(path.join(root, rel)), `reused file missing: ${rel}`);
   }
 });
+
+test('Gemini cannot auto-discover Claude/Codex hook events', () => {
+  assert.equal(
+    fs.existsSync(path.join(root, GEMINI_AUTO_HOOKS)),
+    false,
+    `${GEMINI_AUTO_HOOKS} is auto-loaded by Gemini CLI; keep Claude/Codex hooks on manifest paths`,
+  );
+});

tests/hooks-windows.test.js

@@ -11,7 +11,11 @@ const fs = require('fs');
 const path = require('path');
 
 const root = path.join(__dirname, '..');
-const HOOKS_JSON = 'hooks/hooks.json';
+const HOOKS_JSON = 'hooks/claude-codex-hooks.json';
+const HOST_PLUGIN_MANIFESTS = [
+  '.claude-plugin/plugin.json',
+  '.codex-plugin/plugin.json',
+];
 // cmd.exe variable syntax (%FOO%); PowerShell leaves it literal, breaking the path.
 const CMD_VAR_SYNTAX = /%[A-Za-z_][A-Za-z0-9_]*%/;
 // Pull the hooks/<script> a command launches, so we can check it exists.
@@ -46,3 +50,10 @@ test('every hook command points at a script that ships in hooks/', () => {
     }
   }
 });
+
+test('Claude and Codex manifests point at the shared host-specific hook config', () => {
+  for (const rel of HOST_PLUGIN_MANIFESTS) {
+    const manifest = JSON.parse(fs.readFileSync(path.join(root, rel), 'utf8'));
+    assert.equal(manifest.hooks, `./${HOOKS_JSON}`, `${rel} must not rely on root hooks auto-discovery`);
+  }
+});

tests/hooks.test.js

@@ -8,6 +8,16 @@ const { spawnSync } = require('child_process');
 
 const root = path.join(__dirname, '..');
 
+// isShellSafe gates the statusline setup snippet (issue #200): ordinary install
+// paths pass, paths carrying shell metacharacters are rejected so they never get
+// embedded in a shell command.
+const { isShellSafe } = require('../hooks/ponytail-config');
+assert.equal(isShellSafe('C:\\Users\\x\\.claude\\plugins\\ponytail\\hooks\\ponytail-statusline.ps1'), true);
+assert.equal(isShellSafe('/home/u/.claude/plugins/ponytail/hooks/ponytail-statusline.sh'), true);
+assert.equal(isShellSafe('/tmp/a"&calc.exe&"/x.sh'), false);
+assert.equal(isShellSafe('/tmp/$(calc)/x.sh'), false);
+assert.equal(isShellSafe('/tmp/a;rm -rf/x.sh'), false);
+
 function run(script, env, input = '') {
   return spawnSync(process.execPath, [path.join(root, 'hooks', script)], {
     env: { ...process.env, ...env },
@@ -21,6 +31,9 @@ function run(script, env, input = '') {
 delete process.env.CLAUDE_CONFIG_DIR;
 
 const temp = fs.mkdtempSync(path.join(os.tmpdir(), 'ponytail-hooks-'));
+// Runs on normal exit and on assertion-throw exit; force makes it idempotent.
+process.on('exit', () => fs.rmSync(temp, { recursive: true, force: true }));
+
 const home = path.join(temp, 'home');
 const pluginData = path.join(temp, 'plugin-data');
 fs.mkdirSync(home, { recursive: true });
@@ -64,6 +77,23 @@ assert.equal(fs.existsSync(codexState), false);
 output = JSON.parse(result.stdout);
 assert.equal(output.systemMessage, 'PONYTAIL:OFF');
 
+// A request that merely mentions "normal mode" must not deactivate ponytail.
+result = run('ponytail-mode-tracker.js', codexEnv, JSON.stringify({ prompt: '@ponytail lite' }));
+assert.equal(result.status, 0, result.stderr);
+assert.equal(fs.readFileSync(codexState, 'utf8'), 'lite');
+
+result = run(
+  'ponytail-mode-tracker.js',
+  codexEnv,
+  JSON.stringify({ prompt: 'add a normal mode toggle next to dark mode' }),
+);
+assert.equal(result.status, 0, result.stderr);
+assert.equal(
+  fs.readFileSync(codexState, 'utf8'),
+  'lite',
+  'incidental "normal mode" in a request must not turn ponytail off',
+);
+
 const claudeEnv = {
   HOME: home,
   USERPROFILE: home,
@@ -138,5 +168,4 @@ assert.equal(
 output = JSON.parse(result.stdout);
 assert.deepEqual(output, {});
 
-fs.rmSync(temp, { recursive: true, force: true });
 console.log('hook compatibility checks passed');