feat(opencode/session): default-on hivemind loop primitive (#266 Phase 2)

[terrxo]

Summary

Flip OPENCODE_HIVEMIND_LOOP_ENABLED default from false → true. The hivemind loop primitive (anomalyco#266 Phase 1) shipped behind a feature flag; Phase 2 makes it default-on.

Pairs with hivemind-mcp PR #22 (3-turn grace window for missing-loop-goal).

Why now

Phase 1 validation (post-PR #21 merge) proved:

• The hook is reliably non-fatal — every call is wrapped in Effect.ignore + Effect.forkIn(scope), so the TUI never blocks or sees an exception from a slow/failing hivemind connection.
• The auto-drive payoff is significant: workers signal 🚦 READY FOR REVIEW and the coord wakes automatically; coordinators auto-continue when there's still work to do; idle-phrase + silent-stall escalations route to parents without manual nudges.

Changes

• packages/opencode/src/effect/runtime-flags.ts — hivemindLoopEnabled now Config.boolean(...).pipe(Config.withDefault(true)). Docblock updated to reflect Phase 2 + the opt-out env var.
• packages/opencode/src/session/hivemind-loop-hook.ts — docblock + per-export comments updated to say "default ON" + "opt out via OPENCODE_HIVEMIND_LOOP_ENABLED=0".
• packages/opencode/src/session/processor.ts — call-site comment refreshed.
• GRUNTCODE.md — patch feat(grunt/tui): bare gruntcode auto-spawns serve + attaches (one-command wakeable TUI) #5 description rewritten to reflect default-on + cross-reference the hivemind-mcp grace window.

Opt-out path

To opt out for a specific tab/session:

OPENCODE_HIVEMIND_LOOP_ENABLED=0 gruntcode --peer-id ...

Tests

bun typecheck from packages/opencode is clean.

Pair with

grunt-it/hivemind-mcp#22 — adds the 3-turn grace window so peers that haven't called hivemind_set_loop_goal yet aren't immediately flagged when this default flip lands.

Refs grunt-it/hivemind-mcp#266 Phase 2.

🚦 READY FOR REVIEW

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Hey! Your PR title feat(opencode/session): default-on hivemind loop primitive (#266 Phase 2) doesn't follow conventional commit format.

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