semi implemented and features implemented save checkpoint

docs/features/unchecked/advisoryai/immutable-audit-log-for-ai-interactions.md

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+# Immutable Audit Log for AI Interactions
+
+## Module
+AdvisoryAI
+
+## Status
+IMPLEMENTED
+
+## Description
+DSSE-signed audit envelope builder for chat interactions with prompts, tool calls, and model fingerprints is implemented.
+
+## Implementation Details
+- **Modules**: `src/AdvisoryAi/StellaOps.AdvisoryAI/Chat/Audit/`, `src/AdvisoryAi/StellaOps.AdvisoryAI.WebService/`
+- **Key Classes**:
+  - `AdvisoryChatAuditEnvelopeBuilder` (`src/AdvisoryAi/StellaOps.AdvisoryAI/Chat/Audit/AdvisoryChatAuditEnvelopeBuilder.cs`) - builds DSSE-signed audit envelopes for chat interactions
+  - `ChatAuditRecords` (`src/AdvisoryAi/StellaOps.AdvisoryAI/Chat/Audit/ChatAuditRecords.cs`) - audit record models (prompts, responses, tool calls, model fingerprints)
+  - `PostgresAdvisoryChatAuditLogger` (`src/AdvisoryAi/StellaOps.AdvisoryAI/Chat/Services/PostgresAdvisoryChatAuditLogger.cs`) - persists audit records to PostgreSQL
+  - `NullAdvisoryChatAuditLogger` (`src/AdvisoryAi/StellaOps.AdvisoryAI/Chat/Services/NullAdvisoryChatAuditLogger.cs`) - no-op audit logger for testing
+  - `AttestationEndpoints` (`src/AdvisoryAi/StellaOps.AdvisoryAI.WebService/Endpoints/AttestationEndpoints.cs`) - REST endpoints for attestation/audit retrieval
+  - `NullEvidencePackSigner` (`src/AdvisoryAi/StellaOps.AdvisoryAI/Evidence/NullEvidencePackSigner.cs`) - no-op evidence pack signer for development
+  - `AdvisoryPipelineMetrics` (`src/AdvisoryAi/StellaOps.AdvisoryAI/Metrics/AdvisoryPipelineMetrics.cs`) - metrics collection for audit visibility
+- **Interfaces**: None (uses concrete audit pipeline)
+- **Source**: Feature matrix scan
+
+## E2E Test Plan
+- [ ] Send a chat message and verify `AdvisoryChatAuditEnvelopeBuilder` creates a DSSE-signed envelope containing the prompt, response, and model fingerprint
+- [ ] Verify `ChatAuditRecords` captures tool call invocations with parameters and results
+- [ ] Verify `PostgresAdvisoryChatAuditLogger` persists audit records and they are retrievable via `AttestationEndpoints`
+- [ ] Verify audit envelopes are immutable: attempting to modify a persisted record fails
+- [ ] Verify audit records include model identifier, temperature setting, and token counts
+- [ ] Verify audit log entries are queryable by user, session, and time range