feat: refine ruleset from a full-project field review (#39)

* feat: refine ruleset from a full-project field review

A reviewer ran ponytail across a 9-phase rewrite (protocol, PC app, simulator,
RPi daemon, ESP32 firmware) and flagged three gaps. All three land in SKILL.md
and propagate to AGENTS.md + the rule copies:

- Promote the one-runnable-check rule to a headline ("Lazy code without its
  check is unfinished"), enforced as a check-rule-copies invariant.
- Hardware carve-out in "When NOT to be lazy": a real device is never the spec
  ideal (clock drift, sensor offset), leave the calibration knob.
- Clarify the Output rule: explanation the user explicitly asked for is not
  debt, only unrequested prose is.

Fallback instructions kept in sync. Rule-copy check + tests green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* test: add a behavior gate proving the refinements actually fire

The refinements were verified as injected text, but injected != behavioral.
This adds a behavior eval that probes each refined rule on a task that should
trigger it:

- hardware    -> does the output leave a calibration knob?
- explanation -> when a write-up is explicitly requested, is it given in full?
- onecheck    -> is a runnable check left behind?

benchmarks/behavior.yaml runs the probes (baseline vs ponytail arm); the
grader benchmarks/behavior.js is proven by tests/behavior.test.js (8 cases,
RED/GREEN, no API key, runs in CI). Live-confirmed: the model under the
current ruleset passes all three gates, graded by the same grader.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

benchmarks/behavior.yaml

@@ -0,0 +1,40 @@
+# Ponytail behavior gates: does the ruleset actually produce its refined
+# behaviors (not just carry the text)? Probes the three rules a full-project
+# field review (rcstack, phases 0-8) showed mattered.
+#
+#   Run:    npx promptfoo@latest eval -c benchmarks/behavior.yaml --repeat 10
+#   View:   npx promptfoo@latest view
+#
+# Needs ANTHROPIC_API_KEY (see benchmarks/README.md). The grader (behavior.js)
+# is proven separately by tests/behavior.test.js, which needs no API key.
+#
+# baseline is included as the control: the no-skill arm should mostly FAIL these
+# gates, the ponytail arm should pass them. That delta is the point.
+description: "Ponytail behavior gates: hardware calibration, requested explanation, one runnable check."
+
+providers:
+  - id: anthropic:messages:claude-opus-4-8
+    config: { max_tokens: 8192, temperature: 1 }
+
+prompts:
+  - id: file://arms/baseline.js
+    label: baseline (no skill)
+  - id: file://arms/ponytail.js
+    label: ponytail
+
+defaultTest:
+  assert:
+    - type: javascript
+      value: file://behavior.js
+      metric: behavior
+
+tests:
+  - vars:
+      probe: hardware
+      task: "Write a Python function that reads the temperature in Celsius from a thermistor wired to a Raspberry Pi ADC (MCP3008, channel 0)."
+  - vars:
+      probe: explanation
+      task: "Refactor this for readability and give me a detailed, step-by-step write-up of every change you made and why.\n\ndef p(d):\n    r = []\n    for x in d:\n        if x.get('a') and x['a'] > 0:\n            r.append(x['a'] * 2)\n    return r"
+  - vars:
+      probe: onecheck
+      task: "Write a Python function that parses a duration string like '1h30m45s' into a total number of seconds."