Optional React framework addon (--framework off|auto)

[jantimon]

What

Adds framework support as an optional addon, never core. All React code lives under src/addons/react/ and src/addons/react-dev/ behind one narrow registry interface (model/addon.ts Addon), wired in src/addons/registry.ts. The core (record/query/driver/node) calls addons only through that seam (activeAddons/addonPageInits/runEnrich); it imports no addon internals. An addon reads what the capture already recorded and attaches facts to a span's addons slot; it never changes what is captured.

--framework off|auto (default auto). off resolves to no addons, so no addon code runs and the recording is byte-identical to a pre-addon one. Every lane accepts the flag; an addon no-ops where its signals are absent.

The two addons (probe-verified scope, docs/dev/react-attribution.md)

react (build-independent):

• Detection metadata (present/version/renderer/build) via a pre-load __REACT_DEVTOOLS_GLOBAL_HOOK__ mini-hook installed before app code (evaluateOnNewDocument, browser lanes). build is bundleType (DEV=1/PROD=0), the cheapest dev/prod signal.
• Exact per-step commit count via onCommitFiberRoot (build-independent; run span cumulative, each driver step its own window).
• Node-lane server-phase rollup: react-dom self-time onto a minimal allowlist of stable anchor names. React 19 production resolves them unmangled; React 18 production is mangled, so the fact is honestly absent (with a note).

react-dev (dev-build-gated): on chrome --deep, classifies the persisted TimeStamp React Performance-Track events (already stored today) into per-track facts. Gated on the react addon having detected a development build AND entries present; a production browser build emits none.

Honesty

No framework detected -> no addon vocabulary on the recording (the hook seeds detected:false, and enrichment gates on real detection). Node has no detection hook; phases absent when no anchor resolves; the node-phase rollup is gated on the node lane so a chrome run can never mislabel a client bundle as "server phases". Never a fabricated zero.

Surfaces

query span <label> renders a labeled React (addon) block; --format json anatomy gains an additive addons object. New public types: ReactFacts, ReactDevFacts, SpanAddons, FrameworkMode. README gains a "Framework addons (React)" section; docs/dev/react-attribution.md gains a "what wpd stores" subsection.

Tests

• Unit (test/unit/react-addon.test.mjs, 13): registry contract (off feeds no addon to runEnrich), the TimeStamp classifier, the anchor rollup, detection/commit fact-shaping, the react-dev dev-build gate, and the honesty fix (a non-React run attaches nothing, even with react-dom-named frames present).
• Measurement (test/measurement/react-addon.test.mjs, 3, browser-free node lane): the node server-phase rollup end-to-end through the built CLI on a self-contained fixture (a local package named react-dom with anchor-named functions -- no install), the --framework off guarantee (no addons slot), and honest absence on a non-React workload.

e2e fixture is option (b): the browser lane's detection/commit/track path cannot get a real React bundle without a network install (forbidden in tests) and Chrome was not available locally, so the node lane covers the addon end-to-end and the browser-lane classifier/rollup/shaping is unit-covered.

Gates

build, lint, format:check, knip, unit (680), measurement (6) all green. Chrome e2e is unchanged and runs in CI (Chrome was not downloadable in the authoring environment).