chore(tracing): extract format, reader, and writer (TracingSession) into packages/tracing#40671
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dgozman wants to merge 6 commits intomicrosoft:mainfrom
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chore(tracing): extract format, reader, and writer (TracingSession) into packages/tracing#40671dgozman wants to merge 6 commits intomicrosoft:mainfrom
dgozman wants to merge 6 commits intomicrosoft:mainfrom
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Move the trace format types from packages/trace/ and the reader/model from packages/isomorphic/trace/ into a new packages/tracing/ library (format/ + reader/ + versions under format/). Drop the @trace/* alias in favor of @tracing/*; @isomorphic/trace/* path is gone (callers repointed to @tracing/reader/*). Local copies of small protocol types (StackFrame, Point, SerializedError, ClientSideCallMetadata) live in packages/tracing/src/format/protocolTypes.ts so the new package has no @protocol/* dependency. This is a pure code motion + import rename. Phase 1 of a larger refactor that will also extract a TracingSession writer (server-side trace recording state machine) into packages/tracing/src/writer/.
Move the trace zip assembly (`zip`) and call-stack session bookkeeping
(`tracingStarted`, `traceDiscarded`, `addStackToTracingNoReply`) out of
`packages/playwright-core/src/server/localUtils.ts` and into
`packages/tracing/src/writer/`. The library functions take an
`AbortSignal` instead of a `Progress`; a tiny `race(signal, promise)`
helper in `packages/tracing/src/writer/race.ts` does the
abort-vs-promise race. The dispatcher passes `progress.signal` and
keeps the outer `progress.race(...)` so the eslint progress-rule
stays satisfied. HAR functions in `localUtils.ts` are left untouched.
The new package has no package.json; sources are bundled and
deps live in the root devDependencies. Per-file
\`node_modules/{fs,os,path,events,yauzl,yazl,mime}\` declarations
in \`packages/tracing/src/DEPS.list\` cover what writer/ needs.
…kages/tracing/writer snapshotterInjected.ts is pure DOM logic (no Playwright internals) and now lives next to the rest of the writer; snapshotter.ts imports it via @tracing/writer/snapshotterInjected. mergeTraceFiles, previously a private helper at the bottom of testTracing.ts, is now a generic library function. The test-trace-entry-name special case is exposed as an optional `keepEntryName` parameter; the test runner passes `testTraceEntryName`.
…nto it Extract the disk-backed writer state machine — RecordingState (traceFile/networkFile/resourcesDir/chunkOrdinal/sha1 sets/recording/groupStack), the SerializedFS and tmp-dir lifecycle, the appendTraceEvent / appendResource / appendNetworkEntry path-and-flush logic, the chunk-allocate / change-trace-name routines, and group / groupEnd / closeAllGroups bookkeeping — out of packages/playwright-core/src/server/trace/recorder/tracing.ts and into packages/tracing/src/writer/tracingSession.ts. The session takes an AbortSignal (not a Progress) on stopChunk/stop and uses the local race() helper. A small `replacer` callback handles non-JSON-serializable values (Dispatcher, Buffer, Date) so the session itself stays free of Playwright server types. Server-side Tracing keeps its InstrumentationListener / Snapshotter / HarTracer / screencast roles and forwards every event into the session. _callIds and the original start() options (needed for snapshotter/screencast wiring) move from the recording state onto Tracing as plain fields. tracing.ts drops from ~830 lines to ~530; the rest is the listener methods and screencast/snapshotter glue that genuinely depend on Playwright internals.
Drop the in-memory _traceEvents[] buffer and the separate _liveTraceFile
plumbing in packages/playwright/src/worker/testTracing.ts. Test-runner
events now stream to disk through a TracingSession (one chunk per test,
trace name "<testId>[-retry<N>]-test" so the live viewer's testId-prefix
scan still finds the on-disk .trace file). The final trace.zip is built
by session.stopChunk('archive') and merged with playwright-core's
per-context chunks via mergeTraceFiles.
Attachments and source files are now resolved at append time (sync
fs.readFileSync) and stored as session resources keyed by content sha1
(or src@<pathSha1>.txt for sources). The _options.attachments=false /
sources=false toggles work by skipping the resource step before
emitting the trace event, instead of via a finalize-time filter pass.
testTimeout can change late in the test, so testTracing emits
context-options twice: once at chunk start (with the value at that
point, possibly undefined) and once again in stopIfNeeded with the
final testInfo.timeout. The reader processes events in order and
overwrites context-entry fields, so last-write-wins gives the right
testTimeout in the model.
Two TracingSession tweaks went alongside:
- New `traceEntryName` option (default 'trace.trace'). The test runner
passes 'test.trace' so its main entry survives mergeTraceFiles
unrenamed.
- startChunk no longer auto-emits contextCreatedEvent. Callers
(server Tracing and TestTracing) now appendTraceEvent it
explicitly — server patches walltime/monotonic at chunk start;
TestTracing emits the constructor-time copy and re-emits at stop.
When `sources: true` is set on TracingSession.start(), the session now
walks event.stack[].file for the two event types that carry a stack
('before' and 'error') and accumulates unique source-file paths
per-chunk. At stopChunk time those files are embedded as
`resources/src@<pathSha1>.txt` entries directly from disk (no copy
through resourcesDir).
testTracing.ts loses its _appendSourcesFromStack helper and the
_emittedSourceFiles dedup set: it now just passes
`sources: !!_options.sources` to session.start() and the session does
the rest. As a side effect the per-step sync fs.readFileSync on every
appendBeforeActionForStep / appendForError goes away — source reads
happen once at chunk stop.
Server-side Tracing opts out explicitly with `sources: false`
(per-context source embedding is owned by LocalUtils.zip via the
StackSession callStacks, not the session, so leaving it on would
have been redundant — and worse, would have started pulling
source files in for tracing.group event stacks).
A new tiny helper packages/tracing/src/writer/sourceFiles.ts owns
the `resources/src@<pathSha1>.txt` naming convention so both
TracingSession.stopChunk and LocalUtils.zip use the same form.
pavelfeldman
approved these changes
May 6, 2026
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Summary
Pulls the trace format types, the reader/model, and a new disk-backed
TracingSessionwriter out ofplaywright-coreand the test runner into a self-containedpackages/tracing/library with no@protocol/*or Playwright-server dependency.packages/tracing/src/format/— waspackages/trace/src/. NewprotocolTypes.tscarries local copies of the small structural types previously imported from@protocol/channels(StackFrame,Point,SerializedError,ClientSideCallMetadata).packages/tracing/src/reader/— waspackages/isomorphic/trace/.packages/tracing/src/writer/— new.TracingSessionis the disk-backed state machine extracted from servertracing.ts(RecordingState,SerializedFS, append/resource/network/zip lifecycle, group stack, source-file collection).zip.ts/stackSession.tsare the trace-related halves ofLocalUtils.mergeTraceFiles.tsandsnapshotterInjected.tsco-locate here too.tracing.tsand workertestTracing.tsare now thin wrappers overTracingSession. The test runner's in-memory_traceEvents[]buffer and separate live-trace file are gone — events stream to disk through the session.localUtils.tsare intentionally left untouched (not strictly trace-related).progress: Progressparameters in the moved zip / stack-session functions becomesignal: AbortSignal+ a small localrace(signal, promise)helper.The branch is split into seven self-contained commits, each green on
flintand the trace + library + artifacts test suites.