fix(server): Claude workflow members stream their thinking and tool calls into their threads

[juliusmarminge]

A Claude workflow member's thread showed only its prompt and, since #20786, its text replies so far. There was no thinking and no tool calls, and the whole transcript tail was re-read and rejoined into one message every 10 seconds. Ordinary subagents show their full conversation.

Why members differ

Claude CLI 2.1.301 forwards every message of an ordinary background subagent as SDK frames with parent_tool_use_id. It forwards none from a workflow member: for those it only emits workflow_agent progress entries (state, label, tokens, tool count, previews) on the coordinator task, about every 12 seconds. The member's transcript (<transcriptDir>/agent-<agentId>.jsonl) is the only full record. Its lines have the same shape as SDK frames.

Fix

Read each member's transcript incrementally, and project its lines through the same code as forwarded subagent frames.

• Reader (workflowFileRead.ts): reads from a byte offset, keeping the existing containment, realpath and inode checks.
  • Complete lines only: it returns only complete lines (up to the last \n) and the offset after them, so a half-written line is read whole next time.
  • Restarts: a different inode, or a file shorter than the offset, is read from 0.
  • Long lines: a single line longer than the 512 KB cap is skipped so the cursor can't stall.
• Per member (workflowMemberStates):
  • State kept: a cursor (offset and file identity), its own item ordinals and its own open tool calls.
  • When it reads: each progress frame reads only what's new. Lines already projected are never read or parsed again.
• Projection: new shared helpers take an explicit target thread instead of resolving it from parent_tool_use_id. The live subagent path now uses them too, for thinking, tool call start and tool result.
  • Each transcript line goes through them, so a member's thread shows thinking, tool calls with results, and replies in line order.
  • Items are keyed by the line's own uuid and tool_use ids, so a re-read after a restart adds no items.
• Settling: the settled frame reads from the cursor to the end of the transcript, repeating past the per-read cap so a long member's final answer isn't cut off. Any tool call the member left open is marked interrupted instead of spinning forever.
• Late flush: Claude Code flushes transcript writes every 100 ms, so a member's reply can land after the progress frame that settles it. In a live run, one member's reply is timestamped 45 ms before the read that settled it, but only reached the disk about 55 ms after that read.
  • The excerpt waits: "Partial answer from workflow progress" is shown only from a read that started at least 500 ms after the member settled. Until then a later frame's read picks up the real reply.
  • The last frame: when the coordinator has ended, no later frame comes. That read sleeps out the rest of the window and reads once more before falling back.
  • What counts as the reply: waiting stops once the transcript reaches the end of the member's turn: an assistant line whose stop_reason is a string other than tool_use. Text written before a tool call doesn't count, and a line without the field keeps the turn open.
• Removed: fix(server): a running Claude workflow member shows its answer so far #20786's single overwritten answer message, its 10-second throttle and digest, and the "Retry in progress." / "No answer from this workflow attempt." placeholders. "Partial answer from workflow progress:" stays only for a settled member whose transcript gave no text. workflowAgentAnswers.ts is replaced by workflowAgentTranscript.ts.

Verification

• New and updated ClaudeAdapterV2.test.ts cases (each fails on main):

  • "streams a running workflow member's conversation from its transcript": thinking, a Bash call completing with output, then a reply, in order. Fails with expected [ 'user_message', 'assistant_message' ] to deeply equal [ 'user_message', …(3) ].
  • Incremental read: a read observer records each read.
    • The first read covers bytes 0–1620 and keeps 5 lines; attachment and isMeta lines are dropped.
    • After appending a line and half of another, the next read starts at exactly 1620 and stops before the half line.
    • Once the line is finished, the read after that starts at the previous end. An unchanged file emits nothing.
  • "interrupts the open tool calls of a workflow member that failed".
  • "reads a settled workflow member's transcript to its end past the read cap": about 1.3 MB of replies before the final answer. Without the drain loop it fails with expected [ …(62) ] to have a length of 81 but got 62.
  • "re-reads a workflow member's transcript after a restart without new items".
  • "waits for a settled workflow member's reply to reach its transcript". One member settles while the workflow runs on, and its reply arrives on the next frame. The other's reply is written just after the read the workflow's final notification triggers. Without the wait it fails with no excerpt before the reply: expected [ 'Reply with exactly: A1', …(1) ] to deeply equal [ 'Reply with exactly: A1' ].
    • It runs three ways: with nothing, with text, and with a line without a stop reason before the reply. When the wait ended at any text, the second case failed with expected [ 'Reply with exactly: A2', …(1) ] to deeply equal [ 'Reply with exactly: A2', …(2) ].

• workflowAgentTranscript.test.ts: cursor resume, a half-written line, an inode swap, a shrunk file.

• Existing tests:

  • Transcript fixture lines now carry a uuid, as real lines do.
  • Five race tests that paused inside the removed digest now pause in the read observer at the same point.
  • "answers settled workflow members…" now expects one message per transcript line instead of one joined answer.

• Suites on the current head (main merged in):

  • ClaudeAdapterV2.test.ts and workflowAgentTranscript.test.ts: 269 pass. The one failure, "moves the root's foreground subagents to the background before a steer (never answers)" from fix(server): steering no longer ends running subagents #19210, times out in my sandbox on main too.
  • The Claude replays pass (34).
  • apps/server typecheck shows no errors or warnings; format is clean. Lint shows only the unused layer warning in ClaudeAdapterV2.ts, as main does.

• Live run: a real Claude Haiku 5.5 workflow with two members, each running one Bash command, on a dev server from the layer above. Each member's thread shows its prompt, the Bash call with its output, and its reply, read from the transcript.

  • Before the late-flush fix: one member showed only the progress excerpt, and the other showed the excerpt and then its real reply.
  • After it: both show one real reply.

Before the late-flush fix	After

Limits

• Restart writes: after a server restart, a member's transcript is read from 0. Item ids dedupe, so the thread doesn't change, but ProviderEventIngestor only skips repeated node.updated events, so each turn item and message is written to the event log again. A stored-item check for those would avoid it.
• Nested agents: an Agent tool call inside a member shows as a plain tool call, not a nested subagent.
• Live timing: updates still arrive with the coordinator's progress frames, about every 12 seconds.
• Flush window: the 500 ms wait is a margin over Claude Code's 100 ms flush, not a guarantee. A member whose reply takes longer to land shows the excerpt. Its reply appears below it only if a later progress frame reads the transcript again.

This is the bottom of a stack; the layer above replaces the workflow script that opens a coordinator's thread.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — This PR substantially changes production Claude workflow behavior by projecting workflow-member transcript content, thinking, and tool lifecycle events into threads, with new cursor and retry state management. It also adds static-analysis suppression directives in new files, so the scope and review-policy impact warrant human review.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.9 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	+7 B (+0.1%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+7 B (+0.6%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 13aa882 · PR result: 5f8f181 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

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📝 Walkthrough

The change replaces answer-oriented transcript reads with cursor-based JSONL reads. The Claude adapter incrementally projects workflow-member text, reasoning, and tool activity into child threads. It tracks transcript state across retries and restarts and handles delayed transcript flushes.

Changes: Workflow transcript projection

Layer / File(s)	Summary
Cursor-based transcript reading apps/server/src/orchestration-v2/workflowFileRead.ts, apps/server/src/orchestration-v2/workflowAgentTranscript.ts, apps/server/src/orchestration-v2/workflowAgentTranscript.test.ts, apps/server/src/orchestration-v2/workflowAgentAnswers.ts, apps/server/src/orchestration-v2/workflowAgentAnswers.test.ts	Contained reads can resume from a matching file identity and offset. The transcript reader filters UUID-bearing JSONL entries and returns cursor metadata. The former answer reader and its tests are removed.
Workflow-member transcript projection apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.ts	The adapter projects transcript text, reasoning, and tool activity into child threads. It tracks cursors, ordinals, open calls, and display state. Retries interrupt open calls, and settled members can wait for transcript flushes or emit a progress-result fallback. Shared helpers handle tool-call lifecycle and subagent projection.
Transcript projection validation apps/server/src/orchestration-v2/Adapters/ClaudeAdapterV2.test.ts	Tests cover incremental reads, partial lines, tool projection, interrupted calls, delayed flushes, restart behavior, and separate transcript replies.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant ClaudeAdapterV2
  participant readWorkflowAgentTranscript
  participant readContainedWorkflowFile
  ClaudeAdapterV2->>readWorkflowAgentTranscript: provide transcript directory, agent ID, and cursor
  readWorkflowAgentTranscript->>readContainedWorkflowFile: read contained file from cursor offset
  readContainedWorkflowFile-->>readWorkflowAgentTranscript: return complete lines and file identity
  readWorkflowAgentTranscript-->>ClaudeAdapterV2: return parsed lines and updated cursor
  ClaudeAdapterV2->>ClaudeAdapterV2: project transcript lines and settle tool calls

Loading

Suggested reviewers: maria-rcks

Merge Risk: 🔵 Low · up to 18236

Some workflow-member threads may omit a final reply when it arrives shortly after the member settles. The affected transcript shape is narrow; correcting the turn-end check is advisable before merging.

Pre-merge checks: 3 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Description check		The description clearly covers the problem, implementation, verification, limitations, and screenshots. It omits the required Scope and approval section, including a triaged issue, maintainer approval…	Add a Scope and approval section. Link the triaged bug or discussion with explicit maintainer approval and the approval comment. If this is an obvious small fix that needs no prior approval, explain why that exemption applies; otherwise obt…

Passed checks: 3 passed

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely describes the main change: workflow members now stream thinking and tool calls into their threads.

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Resolution

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Review comments at @apps/server/src/orchestration-v2/workflowAgentTranscript.ts:
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