[HN-104] Knowledge graph panel downloads the entire vault with unbounded concurrency

[ixjosemi]

Problem

The knowledge-graph panel fetches every markdown file in the vault at once, with no concurrency limit:

const entries = await Promise.all(
  markdownPaths.map(async (path) => {
    const result = await readFile(path)
    return [path, result?.content ?? ''] as const
  })
)

Promise.all over markdownPaths means one in-flight request per file, all fired simultaneously. The effect re-runs whenever markdownPaths, readFile or reloadKey change.

Location

apps/web/src/components/workspace/knowledge-graph-panel.tsx:309-331

Impact

A 500-note vault issues 500 concurrent requests on panel open, and holds the full text of the entire vault in browser memory. Browsers cap per-host connections (~6), so the rest queue at the network layer — the burst does not go faster than a pool would, it just removes any ability to prioritise, cancel or show progress. On a large vault the panel stalls with no feedback.

Suggested fix

Short term: a concurrency pool (6-8 in flight) plus an AbortController so a panel close or a reloadKey change cancels the outstanding requests instead of racing the next batch.

Better: a server endpoint that returns the already-built graph, so the client never downloads the vault at all. That also fixes the companion issue about the O(N²) graph build blocking the main thread — both have the same good fix.

Source: independent verification pass (Claude Opus 5). Not part of the HN-001..HN-063 batch.

[ixjosemi]

Companion issue: #465 (O(N²) graph build blocking the main thread). Both are symptoms of the graph being built client-side — a server-side graph endpoint resolves the two at once, so they are worth scoping together rather than fixing independently.