v5.0.0

Major release — recorder-system rewrite plus a load-bearing build-time
extractor bug fix. See MIGRATION-5.md for a step-by-step upgrade guide
covering every breaking change.

Breaking changes

• Recorder → ScopeRecorder. The data-flow channel's recorder
  interface is renamed for naming symmetry with FlowRecorder and
  EmitRecorder. The shape is unchanged — every method, every event
  payload is byte-identical. Only the import name moves. Most
  consumers should be able to do a single find-and-replace.
• attachRecorder → attachScopeRecorder. Same motivation — the
  executor method that wires a ScopeRecorder now carries the channel
  name explicitly.
• Abstract bases → concrete stores (composition pattern).
  SequenceRecorder<T>, KeyedRecorder<T>, BoundaryStateTracker<T>
  remain available for back-compat but are deprecated. The new primitives
  are SequenceStore<T>, KeyedStore<T>, BoundaryStateStore<T> —
  plain storage primitives that consumers compose via a field instead
  of extending. The composed form aligns with the project's Convention 1
  ("one purpose per recorder") and removes the multi-inheritance
  workaround Bracket trackers needed.

Added — new storage primitives

• SequenceStore<T> — 1:N ordered storage shelf. The composable
  replacement for extending SequenceRecorder<T>. Exposes push,
  getAll, getEntryRanges (O(1) per-step ranges for time-travel),
  and aggregate / accumulate / getEntriesUpTo for slider scrub.
• KeyedStore<T> — 1:1 Map storage shelf. Replaces extending
  KeyedRecorder<T>. Exposes set, get, getAll, aggregate,
  accumulate, clear.
• BoundaryStateStore<T> — bracket-scoped transient state shelf,
  algorithmically the DFS-bracket-stack pattern. Open / update / close
  via start, update, stop. Exposes getActive(key), hasActive,
  activeCount. Dev-mode wires the same three leak-detection
  diagnostics the BoundaryStateTracker had.

Added — runId on TraversalContext

Every event the engine fires now carries a runId on
traversalContext. Generated fresh per executor.run() and per
executor.resume(); shared across all events of one run; differs
across consecutive runs of the same executor. Recorders that
accumulate state across runs detect "new run" via
event.traversalContext.runId !== this.lastRunId and reset transient
bookkeeping. See examples/runtime-features/run-id/ for the
canonical patterns.

Added — CommitRangeIndex

A small helper that builds an O(log n) range index over a commit log
for fast "what commits happened between runtimeStageId X and Y"
lookups. Used by Lens for time-travel scrubbing and by any consumer
that needs interval queries over the commit log.

Fixed — BuildTimeExtractor was silently skipped on 6 builder sites

FlowChartBuilder.ts had six methods that produced spec nodes
WITHOUT calling _applyExtractorToNode on them, while every other
spec-producing method did. The result: consumers passing a
BuildTimeExtractor saw their per-node translator skip an entire
category of nodes — most visibly, every Conditional branch mount
spec (the .when() / .otherwise() outputs) was un-extracted.

Fixed sites:

#	Class	Method	Line (pre-fix)
1	DeciderList	addSubFlowChartBranch	179
2	DeciderList	addLazySubFlowChartBranch	224
3	SelectorFnList	addSubFlowChartBranch	450
4	SelectorFnList	addLazySubFlowChartBranch	493
5	FlowChartBuilder	addLazySubFlowChart	1152
6	FlowChartBuilder	addLazySubFlowChartNext	1202

All six now call _applyExtractorToNode after spec construction.
Zero-risk for consumers without an extractor (helper is a no-op when
_buildTimeExtractor is undefined). Consumers with an extractor will
now see their per-node UI shape / metadata applied to branch mount
nodes too.

Documentation

• New MIGRATION-5.md with step-by-step before/after diffs for every
  breaking change.
• New docs/design/v5-recorder-redesign.md — the design memo behind
  the storage-primitive refactor.
• New docs/design/commit-range-index.md — algorithmic background +
  perf notes.
• New docs-site/src/content/docs/api/agent.mdx (and the previous
  recorders.mdx is retired in favor of the per-primitive pages).
• README + every lib/*/README.md updated to use the new names.