fix: audit batch — #133 #129

[almogdepaz]

Two small fixes from the open audit issues. Each is a separate commit with its own regression test. #130 and #131 left open — see below.

Closes

• L16: audit-regressions.test.ts inlines a copy of validateProjectDir #133 refactor: extract validateProjectDir to pure module
  The HTTP-flavored validateProjectDir in routes.ts had its core logic
  duplicated inside tests/unit/audit-regressions.test.ts so the test could
  exercise it without an HTTP response object — drift risk on a
  security-sensitive path-containment boundary. Extracted to
  src/server/validate-project-dir.ts returning a discriminated result;
  routes.ts wraps it; regression test now imports the real function.

• M5: quiescence loop produces stale snapshot for animated TUIs #129 fix(ws): cap quiescence wait at 200ms for animated TUIs
  Always-busy sessions (spinners, htop, watch, claude's pulse spinner)
  never drop below QUIESCE_BYTE_THRESHOLD, so the prefill settle loop
  always waited the full 800ms before snapshotting — capturing a
  mid-redraw frame the live stream then had to overwrite. New
  QUIESCE_ANIMATED_CAP_MS = 200 short-circuits that wait. Common case
  (apps that quiesce) is unchanged. Decision extracted to pure
  quiescenceDecision() for unit testing.

Reverted in this branch

• M10: forceRepaint() accesses ghostty-web private internals #130 ghostty-web private internals — initial attempt (eb0ae2d) added
  a warn-once shim around the existing try { ... } catch {}. Theater:
  a console.warn in a mobile PWA fixes nothing. Reverted in 13cd446.
  Real risk surface: ghostty-web is pinned to 0.4.0, no runtime
  auto-update; only a deliberate dep bump can break the internals. Right
  fix is either a CI test against the bundle or a comment at the
  version-bump site, not defensive code in the hot path. See updated
  issue comment.

Left open

• L10: broker WRITER_QUEUE_CAPACITY can backpressure the read loop #131 broker WRITER_QUEUE_CAPACITY backpressure — issue's user-impact
  claim ("slow clients lose keyboard input + resize") is wrong:
  Frame::InputBinary calls session.write_stdin directly, and
  Frame::ControlRequest runs router.handle synchronously (resize is
  applied before its response queues). Only control-response delivery
  sits behind a full queue, and SubscriptionDropped recovery exists.
  Needs issue rewrite before deciding between hardening and wontfix.

Verification

• bun test — 1483 pass / 0 fail (after revert)
• bunx tsc --noEmit — 32 errors, all pre-existing on main, zero new
• scripts/bundle-app.ts regenerates clean

Out of scope (closed during triage as stale)

• remove pty backend + backend abstraction (tmux-only) #120 — pty backend removal: already gone in main
• L12: injectAgentContext silent fallback on --append-system-prompt rejection #132 — --append-system-prompt silent fallback: removed in 232dc07
• Frontend has no JWT injection — auth-gated deployments non-functional #110 — frontend JWT injection: fixed at public/app.ts:348-349