Session Brain

Builds a searchable topic graph over your agent session history. The output is a sidecar at ~/.claude/session-brain/ — the vault is never touched.

All the heavy lifting is deterministic Python in the obsidian-wiki CLI. Your only job is to name the clusters, which takes exactly one turn and requires reading no transcripts.

When to use which skill

Step 1: Build

obsidian-wiki sessions-build --json

Roughly 3 seconds cold on ~1000 sessions, well under a second incrementally — it re-reads only transcripts whose size or mtime changed. Useful flags:

Report the headline numbers: total sessions, how many have transcripts vs. are history-only, edges, and cluster count.

Step 2: Name the unnamed clusters

obsidian-wiki sessions-clusters --unnamed --json

Each cluster comes with top_terms and exemplars (its three highest-degree sessions, whose titles are already in graph.json). That is all you need. Do not open transcripts to name a cluster — the whole design goal is that naming costs one turn regardless of corpus size.

Write a 3–5 word name and a one-sentence summary per cluster, then:

obsidian-wiki sessions-name --from - <<'EOF'
[{"id": 3, "name": "warden telemetry pipeline", "summary": "Building and debugging the redacted telemetry chain."}]
EOF

Names are stored in names.json keyed by the cluster's dominant vocabulary, not its id — so they survive rebuilds even though cluster ids are positional and shift as the corpus grows. On repeat runs --unnamed is usually empty and this step is free.

If a cluster's terms are genuinely incoherent, name it honestly ("mixed — short sessions") rather than inventing a theme.

Step 3: Report the map

Read clusters.json and tell the user:

• Biggest topics — by size
• What's hot — highest momentum (activity in the last 30 days vs. the 60 before it)
• What's gone quiet — dormant: true (low recency and nothing in 60 days)
• Where topics meet — bridges, the sessions that connect two otherwise separate topics. These are often the most interesting sessions in the graph.

Then offer the visualisation:

open ~/.claude/session-brain/graph.html

Node size is session length, brightness is recency, hollow rings are history-only sessions, and gold borders are bookmarked ones. The time slider and search box filter together.

Notes

• Never write to the vault from this skill. If the user wants session knowledge in the vault, that is wiki-history-ingest.
• History-only sessions are real. Roughly 40% of a long-lived cache exists only as prompts in history.jsonl; those get graph nodes and are findable, but can never be loaded. Say so plainly rather than implying they are missing.
• The graph is derived data. If it looks wrong, --full rebuilds from scratch; nothing is lost.