feat(routing): engage modes + sender scope + accumulate/drop + per-agent fan-out

Replaces the opaque trigger_rules JSON + response_scope enum on
messaging_group_agents with four explicit orthogonal columns:

    engage_mode            'pattern' | 'mention' | 'mention-sticky'
    engage_pattern         regex source; required when mode='pattern';
                           '.' is the "always" sentinel
    sender_scope           'all' | 'known'
    ignored_message_policy 'drop' | 'accumulate'

Inbound routing becomes a fan-out — every wired agent is evaluated
independently. A match gets its own session + container wake. A miss
with accumulate keeps the message as context-only (trigger=0) in that
agent's session, so when the agent does eventually engage it sees the
prior chatter.

## Schema

- Migration 010 (`engage-modes`): adds the 4 new columns, backfills
  from trigger_rules.pattern + requiresTrigger + response_scope, drops
  the legacy columns.
- messages_in gains `trigger INTEGER NOT NULL DEFAULT 1` (session DB
  schema + `migrateMessagesInTable` forward-compat).
- countDueMessages gates waking on `trigger = 1`.

## Routing

- `pickAgent` (returns one) → loop over all wired agents. Per agent:
  evaluate engage_mode; run access gate + sender-scope gate; on full
  match → resolveSession + writeSessionMessage(trigger=1) + wake. On
  miss with accumulate → writeSessionMessage(trigger=0), no wake. On
  miss with drop → skip.
- New `findSessionForAgent(agentGroupId, mgId, threadId)` scopes
  session lookup by agent so fan-out doesn't cross sessions.
- `messageIdForAgent` namespaces inbound message ids by agent_group_id
  so PRIMARY KEY doesn't collide across per-agent session DBs.

## Adapter layer

- `ConversationConfig` replaces `triggerPattern` + `requiresTrigger`
  with `engageMode` + `engagePattern`.
- Chat SDK bridge stores `Map<platformId, ConversationConfig[]>` (multi-
  agent per conversation) and applies union gating pre-onInbound:
    * onSubscribedMessage: engage if any wiring keeps firing in
      subscribed state (mention-sticky or pattern)
    * onNewMention: engage on mention; only subscribes the thread if
      at least one wiring is `mention-sticky`
    * onDirectMessage: engage per mode; sticky follows same rule
- Bridge no longer unconditionally calls `thread.subscribe()`.

## Sender scope

- Permissions module registers a second hook `setSenderScopeGate` that
  runs per-wiring after the existing access gate. `sender_scope='known'`
  requires canAccessAgentGroup(); `'all'` is a no-op. Not installed →
  no-op everywhere (default allow).

## Container side

- Host passes `NANOCLAW_MAX_MESSAGES_PER_PROMPT` (reuses existing
  MAX_MESSAGES_PER_PROMPT config; was dead code from v1).
- `getPendingMessages` queries `ORDER BY seq DESC LIMIT N`, reverses to
  chronological order for the prompt — accumulated context rides along
  with trigger rows up to the cap.
- `MessageInRow` gains `trigger: number` so the container can tell them
  apart in downstream code (container still processes both; only the
  host uses `trigger=0` for don't-wake).

## Defaults (per ACTION-ITEMS item 1 decision)

- DM (is_group=0): `engage_mode='pattern'`, `engage_pattern='.'` (always)
- Threaded group: `engage_mode='mention-sticky'` (seed-discord)
- Non-threaded group / CLI: pattern '.' in bootstrap scripts

## Tests

- src/host-core.test.ts: 3 new cases — fan-out (2 agents, 2 sessions,
  2 wakes), accumulate (trigger=0 + no wake), drop (no session created).
- Existing 10 host-core tests still pass.
- Migration 010 runs on an empty DB in 0-row path — verified.

Closes: ACTION-ITEMS items 1, 4.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/init-first-agent.ts

@@ -195,8 +195,13 @@ async function main(): Promise<void> {
       id: generateId('mga'),
       messaging_group_id: mg.id,
       agent_group_id: ag.id,
-      trigger_rules: null,
-      response_scope: 'all',
+      // DM (is_group=0) defaults to "respond to everything" via the '.' pattern.
+      // Group chats default to mention-only; admins can upgrade to
+      // mention-sticky via /manage-channels once the agent is in use.
+      engage_mode: mg.is_group === 0 ? 'pattern' : 'mention',
+      engage_pattern: mg.is_group === 0 ? '.' : null,
+      sender_scope: 'all',
+      ignored_message_policy: 'drop',
       session_mode: 'shared',
       priority: 0,
       created_at: now,
@@ -248,8 +253,11 @@ async function main(): Promise<void> {
       id: generateId('mga'),
       messaging_group_id: cliMg.id,
       agent_group_id: ag.id,
-      trigger_rules: null,
-      response_scope: 'all',
+      // CLI is a local single-user DM — always respond.
+      engage_mode: 'pattern',
+      engage_pattern: '.',
+      sender_scope: 'all',
+      ignored_message_policy: 'drop',
       session_mode: 'shared',
       priority: 0,
       created_at: now,

scripts/seed-discord.ts

@@ -58,8 +58,12 @@ try {
     id: 'mga-discord',
     messaging_group_id: MESSAGING_GROUP_ID,
     agent_group_id: AGENT_GROUP_ID,
-    trigger_rules: null,
-    response_scope: 'all',
+    // Discord group channel → mention-sticky default. Mention once, stay
+    // subscribed to the thread. Admins can tune via /manage-channels.
+    engage_mode: 'mention-sticky',
+    engage_pattern: null,
+    sender_scope: 'all',
+    ignored_message_policy: 'drop',
     session_mode: 'shared',
     priority: 0,
     created_at: new Date().toISOString(),

scripts/test-v2-channel-e2e.ts

@@ -53,8 +53,10 @@ createMessagingGroupAgent({
   id: 'mga-chan',
   messaging_group_id: 'mg-chan',
   agent_group_id: 'ag-chan',
-  trigger_rules: null,
-  response_scope: 'all',
+  engage_mode: 'pattern',
+  engage_pattern: '.',
+  sender_scope: 'all',
+  ignored_message_policy: 'drop',
   session_mode: 'shared',
   priority: 0,
   created_at: new Date().toISOString(),
@@ -105,7 +107,15 @@ registerChannelAdapter('mock', { factory: () => mockAdapter });
 
 // Init channel adapters — this calls setup() with conversation configs from central DB
 await initChannelAdapters((adapter) => ({
-  conversations: [{ platformId: 'mock-channel-1', agentGroupId: 'ag-chan', requiresTrigger: false, sessionMode: 'shared' }],
+  conversations: [
+    {
+      platformId: 'mock-channel-1',
+      agentGroupId: 'ag-chan',
+      engageMode: 'pattern',
+      engagePattern: '.',
+      sessionMode: 'shared',
+    },
+  ],
   onInbound(platformId, threadId, message) {
     routeInbound({
       channelType: adapter.channelType,

scripts/test-v2-host.ts

@@ -55,8 +55,10 @@ createMessagingGroupAgent({
   id: 'mga-e2e',
   messaging_group_id: 'mg-e2e',
   agent_group_id: 'ag-e2e',
-  trigger_rules: null,
-  response_scope: 'all',
+  engage_mode: 'pattern',
+  engage_pattern: '.',
+  sender_scope: 'all',
+  ignored_message_policy: 'drop',
   session_mode: 'shared',
   priority: 0,
   created_at: new Date().toISOString(),