Sync fork to upstream b9ca4b7 — the UI/Steps work, verified engine-neutral #13

Why now

Not for a fix we need. Upstream has not tagged since v1.6.0, and the 60 commits
sitting on main are almost entirely new surface — the codegraph ui browser
viewer and the Steps/Screens route visualisations. We take them so those features
are available to us later, and so the next sync is a short hop rather than another
long one.

FORK.md's policy prefers a tagged base and allows an untagged commit as the
exception. This is that exception, so the base is the commit id — b9ca4b7
(main, 2026-08-31) — and nothing upstream has vetted it. The verification below
is ours.

What is in the 60 commits

The engine directories that changed are almost all additions: of the 28 files
touched under src/resolution, 16 are new framework synthesizers. The kernel
change is confined to tsjs/. src/db/schema.sql and src/db/migrations.ts are
untouched, which is what matters most for us — FM-Agent reads codegraph.db
directly.

Verification

Every calls edge compared between the current release build (1.6.0-fmagent.1)
and this base, keyed on call-site position (file, line, column) rather than on
names — a name-keyed comparison lies whenever a fix renames nodes.

The thirteen are the entire drift and they are a fix: toast.show() used to
resolve to the receiver toast and now resolves to the method show (upstream's
object-literal namespace-member resolution — checked against the source). They are
in upstream's own .svelte files, a file type FM-Agent does not index.

The Svelte row is also what makes the zero rows worth trusting: it shows the
comparison detects change when there is change to detect.

Also run:

• Suite — 237 files, 4,229 passing. The only failures are git-hooks.test.ts
  (4), which fail on any machine with a global core.hooksPath; unrelated to this
  base.
• Regression benchmark, depth 1 — 4/4 on both the old and the new build.
• Release bundle — darwin-arm64 builds (56 MB, viewer and native kernel
  included); extracted and re-indexed leveldb to exactly the same 5,720 calls
  edges as the working-tree build.

Two things this base adds to the fork's maintenance

1. The version marker now lives in two files. Upstream's new
ui-package.test.ts asserts ui/package.json matches the engine's
package.json, so bumping only the root turns the suite red. Recorded in
FORK.md.

2. Upstream changed how the test runner discovers tests — vitest.config.ts
renamed to .mts, and a new vitest.workspace.mts splits the suite into an
engine project and a ui one (the Svelte component test needs jsdom and browser
resolution conditions that must not reach the engine suites). This is exactly the
scenario FORK.md has been warning about: our workdir-exclusion regression test
could have stopped being collected without anything going red. It is still
collected — verified by running it, not by reading the config. The check to repeat
after a future sync is now written down in FORK.md.

For the release notes

EXTRACTION_VERSION goes 25 → 26, so every project gets one forced full re-index
after upgrading.