fix: catch IntegrityError on sessions.title UNIQUE index creation

[AlexFucuson9]

Summary

hermes_state.py line 1783 creates a UNIQUE index on sessions.title but only catches sqlite3.OperationalError. When duplicate titles exist in the database, SQLite throws sqlite3.IntegrityError instead — which is uncaught, crashing Dashboard API calls to /api/sessions/{id}/messages.

Root Cause

Commit 60b6abefd (feat: session naming with unique titles) added the UNIQUE INDEX but only catches OperationalError ("index already exists"). It doesn't handle the case where the index doesn't exist yet but the table already has duplicate titles — which throws IntegrityError.

This can happen through:

• Session imports with non-unique titles
• Context compression creating duplicate continuation titles
• Race conditions in concurrent session creation

Fix

Catch sqlite3.IntegrityError before OperationalError. When caught:

1. Deduplicate sessions by keeping the newest row per title
2. Retry the index creation

Changes

• hermes_state.py: Add IntegrityError handler with deduplication logic

Test Plan

• Unit tests pass
• Verified with duplicate titles in test database
• Dashboard API no longer crashes on duplicate session titles

Fixes #65602

[tonydwb]

Code Review Summary

Verdict: Comment

Scope

• 1 file (hermes_state.py), +12 lines
• Handles IntegrityError when creating a UNIQUE index on sessions.title if duplicate titles already exist — deduplicates by keeping newest row before retrying the index creation.

Observations

• Correct error handling: Catches the specific IntegrityError, deduplicates with a clear strategy (keep newest), then retries the index creation.
• GROUP BY + MAX(rowid) is a standard SQLite deduplication pattern — appropriate here.
• Minor: the WHERE clause in the DELETE subquery is redundant since the index is already filtered on , but harmless.

Looks Good

• Focused, well-scoped fix for a real DB migration edge case
• No impact on other code paths

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Reviewed by Hermes Agent

[tonydwb]

Code Review Summary

Verdict: Comment

Scope

• 1 file (hermes_state.py), +12 lines
• Handles IntegrityError when creating a UNIQUE index on sessions.title if duplicate titles exist — deduplicates by keeping newest row before retrying the index creation.

Quality

• GROUP BY + MAX(rowid) is a standard SQLite deduplication pattern.
• Clear, focused fix for a real DB migration edge case.
• No impact on other code paths.

Looks Good

• Well-scoped error handling in schema init.

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Reviewed by Hermes Agent

[teknium1]

Closing in favor of PR #65689 (salvaged from #65636). You were first on this bug and the IntegrityError diagnosis was spot-on — thank you for the report-quality root cause. The reason we went with the other implementation: the dedup DELETE here keeps only MAX(rowid) per non-null-title group, which means every untitled session (the majority of normal sessions) falls outside the subquery and gets deleted, along with their transcripts. #65689 repairs by NULLing the older duplicate aliases instead, preserving every row. Credited you in the merged PR discussion — thanks again for surfacing this.