docs(history): add session snapshot for 2026-04-15 part 2" -m "- finalize CanonicalUser contract enforcement (extra=forbid)

- document production-correct AD dual-account and privileged OU handling
- record policy-aware identity confidence implementation status
- capture explainability improvements in identity output semantics
- note Entra admin-consent as external blocker with clean handoff next steps

documentation/project-history/SESSION_SNAPSHOT_2026-04-15_2.md

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+# Session snapshot - 2026-04-15 (Part 2)
+
+**Branch:** main  
+**Status:** Clean working tree, no staged changes
+
+---
+
+## Session goals
+
+Capture and lock in the completed identity architecture work so the next session can resume immediately when Entra admin consent is available.
+
+---
+
+## Accomplishments
+
+- Finalized and enforced the CanonicalUser contract, including strict validation behavior with extra-forbid constraints.
+- Completed a production-correct AD pipeline, including handling for dual-account and privileged OU scenarios.
+- Implemented policy-aware identity confidence logic and validated expected behavior.
+- Improved output semantics so responses explain why decisions were made, not only what was returned.
+- Confirmed Entra readiness state is blocked only by admin consent, not by schema or implementation quality.
+- Reached a stable pause point with no known broken flows and no active regression indicators.
+
+---
+
+## Technical debt / pending
+
+- Entra integration remains pending external admin consent.
+- Manager resolution work remains open.
+- Explicit identity health MCP tool remains open.
+- Post-consent validation run is still required once credentials are approved.
+
+---
+
+## Next steps
+
+1. Obtain Entra admin consent and approved credentials.
+2. Plug in Entra credentials without schema changes.
+3. Run identity correlation validation to confirm confidence scoring with live Entra signals.
+4. Choose one focused follow-up track:
+   - Manager resolution, or
+   - Explicit identity health MCP tool.
+5. Capture results in a new snapshot after first post-consent validation pass.
+
+---
+
+## Handoff note
+
+You are pausing in a high-quality state: core contracts are hardened, AD logic is production-aligned, confidence policy is active, and Entra is waiting on access approval rather than engineering rework.