feat(viz): code-graph lands on a connected hub neighbourhood + server-backed file search

[sshanzel]

What changed

The code-graph tab dumped the first 800 files (an arbitrary, unreadable black wall) for any sizeable repo — the last viz hairball from the cold-start validation pass. It now lands on a connected hub neighbourhood:

• collectCode ranks files by coupling degree and grows a connected neighbourhood from the densest hubs (each hub + its neighbours) up to CODE_LANDING_CAP (80). This shows real coupling structure — not 800 dots, and not isolated hubs (top-degree-alone are edgeless, since hubs connect to leaves, not each other). Small repos (≤80 files) still show in full. Note reads "Showing the 80 most-connected files of N — double-click to expand, or search to load any file."
• New searchFiles (parameterized $q path-CONTAINS, never string-concatenated) + /api/search route so the UI search reaches files outside the landing set. doSearch highlights loaded matches instantly, then debounced-fetches and adds matching files to the graph; double-click then expands their neighbours.

Before	After
800-file black wall (arbitrary slice)	80 most-connected files, connected hub-and-spoke, readable paths

Verification

Reviewer (healthy graph): 80 nodes / 293 edges, connected structure, file paths legible. Search verified: daemon → loads daemon.ts/daemon.test.ts (not in the landing set).

Playright renders edgeless (1349 files, 0 import/ref/cochange edges) because its index is the incomplete one from the generated-file Symbol-PK crash — a separate known launch-checklist bug, not this change.

How to test

• pnpm test:unit (553) — ui.test asserts the search wiring (fetchSearch + /api/search). The Kùzu-backed collectCode is exercised by the manual plex serve E2E (no Kùzu in a .test.ts, ADR-17). pnpm typecheck + pnpm build green.
• Manual: plex serve → Code graph tab on a real repo → connected hub view; type a non-hub filename → it loads.

Notes

This closes the "seeing the graph" track (all three tabs — Knowledge, Review history, Code graph — now legible). The playright edgeless-index bug (generated-file Symbol PK) remains a separate launch-checklist item.

🤖 Generated with Claude Code

[sshanzel]

Plex review feedback addressed — ready for re-review.

The Plex review (run in-session; not posted as GitHub threads) raised 1 bug + 2 improvements + 2 nits. All five are fixed; two flagged risks came back clean.

Item	Class	Outcome
1. Stale debounced search response re-highlights against the old query	bug	Fixed in 5ca6f4d: a searchGen token drops stale/out-of-order responses (gen !== searchGen) and re-highlights against the CURRENT input, not the captured query.
2. Repeated searches grow the graph unboundedly	improvement	Fixed in 5ca6f4d: search-added nodes carry a searched class; the previous batch is evicted before the next is added (landing + expansions untouched).
3. 503 on /api/search showed "retrying…" but never retried	improvement	Fixed in 5ca6f4d: fetchSearch now actually retries with bounded backoff (≤5), gated on the generation so a superseded query stops.
4. Landing note said "most-connected" even on an edgeless graph	minor	Fixed in b6826ca: an edgeless graph now reads "Showing N of M files (no import/co-change edges indexed yet) — search to load any file."
5. Last hub at the cap boundary could land as an isolated dot	minor	Fixed in b6826ca: the growth loop won't add a hub-with-neighbours when there's no room left for a neighbour (a degree-0 file can still fill the final slot).

Verified clean (no change): LIMIT $lim with an int param is supported in kuzu@0.11.3; toLower(...) CONTAINS $q is correctly parameterized (no injection); added nodes flow through the same textContent-only path (XSS holds); included can't exceed the cap.

Tests: items 1–3 — ui.test assertions for the gen-guard, eviction, current-input re-highlight, and retry (the client JS has no DOM/cytoscape harness, so string-presence is the convention here); also verified at runtime (search loads a non-hub file, a rapid query switch exercises the gen path, no page errors). Items 4–5 — collectCode opens Kùzu (not unit-testable, ADR-17); verified manually (edgeless note fires; the connected landing — reviewer: 80 nodes / 293 edges — is unchanged).

Checks: pnpm typecheck, pnpm test:unit (554), pnpm build, client-JS syntax — all green.

No GitHub review threads existed to reply to/resolve (the review was in-session).