v0.18.0

Merges the probe-app branch, and corrects a measurement in 0.17.0's favour.

Added

• probe/ - two self-driving probe apps (riverpod_probe on
  flutter_riverpod 3.4.2, bloc_probe on flutter_bloc 9.1.1) and
  probe/measure.mjs, the harness. Each app runs a five-phase workload and
  prints a phase marker before every phase, so an event on the VM Service can
  be attributed to what caused it. Claims about state-management observability
  are now re-checkable instead of remembered.
• export_session (P3) - the session as versioned JSON. full archives
  everything; brief carries the diagnoses plus only the events their evidence
  cites. One measured example, on probe/riverpod_probe: 22 events / 19KB
  against 417 / 152KB. The ratio depends entirely on how much the session
  captured and how much of it the diagnoses cite.
• get_state_activity - query state-change activity directly rather than
  only through findings.

Fixed

• Bloc: both earlier conclusions were wrong, in opposite directions. The
  merged branch concluded stock Bloc was invisible - 143 transitions, zero
  events, no ext.bloc.* RPC. All of that is true, and the conclusion still did
  not follow: flutter_bloc 9.1.1 depends transitively on provider (its own
  pubspec.lock), and provider posts provider:provider_changed, so a
  flutter_bloc app is not silent.

  The correction then overstated in the other direction. Measured on the probe:
  20 transitions against ~1,220 provider events, because stormWatchers = 60
  widgets each watch the bloc. provider:provider_changed fires once per
  notified dependent, not once per transition - so the count measures how many
  widgets were notified, Bloc transition counts cannot be recovered from it, and
  Bloc itself remains uninstrumented for the VM Service.

  What is now claimed, and no more: there is no ext.bloc.* RPC; flutter_bloc
  depends on provider; provider emits change notifications; therefore a Bloc app
  on that dependency path exposes state-related activity indirectly. Bloc
  internals are not directly observable, and an app avoiding provider-backed
  lookup would be silent here. probe/EVIDENCE.md records each measurement with
  its kind (observed / inferred / documented) and what it does not establish.

Fixed - audit pass

• The session export leaked the VM Service auth token. export_session
  carried session.wsUri verbatim, and the path segment of a VM Service URI is
  a credential granting evaluate, i.e. arbitrary Dart execution in the running
  app - in an artifact whose stated purpose is to be attached to bug reports.
  Redaction now happens inside exportSession itself rather than at one call
  site, so the artifact is safe regardless of caller. Host and port survive.
• stateFinding reported saturated activity as a discovery. With continuous
  state churn - exactly what a rebuild storm produces - every frame falls inside
  the 1s window and the ratio reads 100% whether or not jank is related. It now
  computes the same ratio for smooth frames as a control and withholds the
  finding when the difference is under 15 points. Documented as a correlation
  heuristic, with the symmetric window called out: it cannot show the state
  change came first.
• stateFinding was invoked twice, duplicating itself in every performance
  diagnosis - a merge artifact git resolved silently.
• The reconnection give-up event was emitted asynchronously, behind an adb
  subprocess call added in 0.15.0. The most important record in a session's
  timeline was gated on an optional external tool that can block, making the
  test flaky (1 run in 3) and the behaviour genuinely wrong. The terminal event
  is now recorded synchronously; the transport explanation follows as a separate
  enriching event.
• Corrected three places that contradicted each other on Bloc after the merge:
  performance.ts claimed Bloc announces on the Extension stream, and
  stateActivity.ts claimed Bloc is invisible.

Changed

• diagnose_performance's state finding now measures the fraction of janky
  frames falling within 1s of state activity, rather than comparing raw volumes
  • a falsifiable claim instead of two counts side by side. Scored 0.5, below
    every causal finding, because churn and expensive builds both follow the same
    tap.
• The state collector registers its handler before subscribing, per 0.16.0. The
  branch predated that fix and would have reintroduced it.