v0.7.4 — Deterministic parent-session attribution

What's New

Deterministic parent-session attribution (session-parent-link)

Fixes an edge case where sub-agent cost rollup could silently drop spend when the harness header lacked a parentSession field at session_start time.

Changes

• activateSession() late-binding: first non-undefined parent wins; never overwrites a set parentSessionId
• setParentIfAbsent(): private helper encapsulates the immutable-parent rule (unit-testable in isolation)
• resolveParentFromHeader(): wraps getHeader()?.parentSession with error handling — never throws
• Header-first resolution at session_start and session_branch
• Fallback path in turn_start: when header has no parent, falls back to the previously-active session ID
• Disagreement detection: logs [model-router] parent attribution disagreement when header and fallback differ; prefers header
• Debug logging: attribution source tagged as header | fallback | none per scope, idempotent via parentAttributionLogged set

Tests

9 new tests in test/session-parent-link.test.ts covering all attribution paths, error resilience, late-binding, and finalizeChildSession rollup integration.

Diagnosing missing rollup

Enable debug: true in ~/.omp/agent/model-router.json and look for:

[model-router] parent attribution: child=<id> source=<header|fallback|none> parent=<id>

If you see source=none for a session you expected to be a child, the harness header has no parentSession for that session — the issue is upstream, not in the router.

Full Changelog

v0.7.3...v0.7.4