Bug

hermes-achievements lifetime progress regresses after session pruning.

A → B:

• sessions.auto_prune=true
• old rows are deleted from ~/.hermes/state.db
• hermes-achievements recomputes lifetime counters from SessionDB.list_sessions_rich()
• lifetime achievements lose history
• unlocked/discovered state can move backward

This makes session pruning incompatible with lifetime achievements.

Repro / observed data

Environment:

• Hermes Agent: v0.14.0 (2026.5.16)
• Dashboard achievements plugin: bundled hermes-achievements
• DB: ~/.hermes/state.db

Before prune / from backup:

• sessions: 516+
• achievements: 57/60

After sessions.retention_days=14 prune + VACUUM:

• sessions: 350–354
• achievements: 54/60

After merging the pre-prune DB backup back into current DB:

• sessions: 522
• messages: 36801
• achievements: 57/60
• scan: 522/522
• is_stale=false

Example restored scan output:

unlocked_count: 57
discovered_count: 3
total_count: 60
scan_meta.mode: full
sessions_scanned_so_far: 522
sessions_expected_total: 522

Current code path

Relevant file:

plugins/hermes-achievements/dashboard/plugin_api.py

The scan path uses SessionDB:

sessions_meta = db.list_sessions_rich(
    limit=db_limit,
    include_children=True,
    project_compression_tips=False,
)

Then lifetime counters are recomputed from the scanned sessions:

return {
    "sessions": sessions,
    "aggregate": aggregate_stats(sessions),
    ...
}

So if pruned sessions are no longer in state.db, lifetime achievement counters drop.

Why this is a design bug

state.db sessions are operational history and can be pruned for performance.

Achievements are lifetime state and should be monotonic.

Those lifecycles conflict if achievements are recomputed only from the prunable sessions table.

Expected behavior

Session pruning should not reduce lifetime achievements.

Once progress is earned, it should not regress just because old session rows were pruned.

Possible fixes

Preferred:

Persist lifetime counters in ~/.hermes/plugins/hermes-achievements/state.json and merge with scanned values monotonically:

counter = max(persisted_counter, scanned_counter)

Then pruning state.db cannot reduce lifetime achievements.

Alternative:

Scan archived session files under:

~/.hermes/sessions/

But this needs careful dedupe across session_*.json, *.jsonl, WebUI sessions, cron/background sessions, etc.

Less ideal:

Hook session pruning to run achievements aggregation first, then persist counters before deleting old rows.

Risk

Users enabling session pruning or running VACUUM after prune can permanently lose achievement history unless they still have a state.db backup.