feat(mcp/plugin): add opening council-scene contract to parse_mode

[JeremyDev87]

Summary

• Add councilScene field to parse_mode MCP response for PLAN/EVAL/AUTO modes, enabling the assistant to open its first response with a Tiny Actor council scene
• ACT mode and unrelated prompts omit the field entirely (backward-compatible)
• Add equivalent build_council_scene() method to standalone mode_engine.py for MCP-independent usage

Changes

MCP Server (apps/mcp-server/)

• council-scene.types.ts: CouncilScene and CouncilSceneCastMember interfaces
• council-scene.builder.ts: Pure function resolving cast from councilPreset (PLAN/EVAL), visual data, or fallback agent IDs (AUTO)
• mode.handler.ts: Integrate buildCouncilScene() into response pipeline
• council-scene.builder.spec.ts: 8 unit tests
• mode.handler.spec.ts: 7 integration tests (PLAN/EVAL/AUTO enabled, ACT excluded, cast shape, serialization)

Standalone Plugin (packages/claude-code-plugin/)

• mode_engine.py: COUNCIL_PRESETS, MODERATOR_COPY dicts + build_council_scene() method
• test_mode_engine.py: 12 new tests

Test plan

• yarn workspace codingbuddy test — 6150 passed, 0 failed
• python3 -m pytest test_mode_engine.py — 48 passed
• yarn workspace codingbuddy build — clean
• yarn lint --fix — no errors in changed files
• yarn prettier --write . — formatted

Closes #1366

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
codingbuddy-landing	Ready	Preview, Comment	Apr 6, 2026 11:14am

[JeremyDev87]

Review: APPROVE

CI Status: PASS

All 29 checks passed (lint, typecheck, build, tests, security, format, circular, e2e, plugin, landing, rules).

Code Quality

• Clean architecture: Pure function builder (council-scene.builder.ts) with no I/O — types → builder → handler separation
• No any types: All interfaces explicitly typed (CouncilScene, CouncilSceneCastMember)
• No unused imports: All imports consumed
• No dead code
• Python parity: mode_engine.py mirrors MCP server structure (COUNCIL_PRESETS, MODERATOR_COPY, build_council_scene)

Spec Compliance (Issue #1366)

All acceptance criteria met:

• ✅ MCP parse_mode response includes councilScene contract for PLAN/EVAL/AUTO
• ✅ Standalone mode includes equivalent contract via build_council_scene + build_instructions
• ✅ Scoped to workflow requests — ACT mode returns undefined/None
• ✅ Deterministic output — fixed moderatorCopy strings, locked format tiny-actor-grid

Test Coverage (27 new tests)

• Builder unit: 9 tests — mode routing, data resolution strategies (preset/visual/fallback), face cross-reference, single primary, JSON serializable
• Handler integration: 7 tests — PLAN/EVAL/AUTO enabled, ACT excluded, cast structure validation
• Python standalone: 11 tests — mode routing, cast structure, preset match, case insensitivity, instructions integration, JSON serializable

Issues Found

• [low]: migrate-legacy-hooks.js has an unrelated prettier formatting change ((line) => → line =>). No functional impact.

Recommendation: APPROVE

[JeremyDev87]

✅ Review complete - review agent approved

Review Summary

• Issues found: 1 (medium/low only)
• Critical: 0, High: 0
• Recommendation: APPROVE

LGTM - ready to merge.