FN-6228: prioritize project model overrides
Ensure saved project model settings outrank stale durable-agent runtime models across AI lanes.
- Document the updated task, heartbeat, validator, merger, and summarizer model precedence.
- Add model-resolution regression coverage for project lanes, globals, defaults, runtime fallback, and test-mode mock forcing.
- Route AI merge body summarization through the shared title-summarizer settings resolver.
- Preserve upstream triage prompt coverage for TRIAGE_POLICY_PROMPT while resolving conflicts.
Files changed:
docs/agents.md | 18 +--
docs/settings-reference.md | 32 ++--
.../core/src/__tests__/model-resolution.test.ts | 98 ++++++++++++
packages/core/vitest.config.ts | 1 +
.../src/__tests__/agent-session-helpers.test.ts | 173 +++++++++++++++++++++
.../src/__tests__/merger-ai-merge-body.test.ts | 85 +++++++++-
packages/engine/src/agent-session-helpers.ts | 4 +
packages/engine/src/merger.ts | 26 +---
8 files changed, 392 insertions(+), 45 deletions(-)
Fusion-Task-Id: FN-6228
Fusion-Task-Lineage: a6c03f2a-dde7-4037-bdcd-a1c92a8b7fae
905d5bf849