* fix subagent total delegation cap
* fix embedded subagent run cap context
* fix subagent cap config consistency
* fix resumed subagent run cap boundary
* fix legacy resume subagent boundary
* address subagent cap review feedback
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
Phase 2 of #3875. Two guardrail axes can end a subagent run early — the turn
budget (GraphRecursionError) and the token budget (TokenBudgetMiddleware) —
and both now surface *why* through one additive `subagent_stop_reason` field
instead of a status enum.
This completes and course-corrects Phase 1 (#3949), which shipped the
turn-budget cap as a `max_turns_reached` status enum. The agreed Phase 2
design replaces that enum with an optional `stop_reason` field
(token_capped | turn_capped | loop_capped): a new enum value would break v1
consumers, while an additive field is ignored by older frontends and ledger
readers. `max_turns_reached` and SubagentStatus.MAX_TURNS_REACHED are removed.
- subagents.token_budget config (default enabled, 2,000,000 tokens, warn 0.7)
with per-agent override; TokenBudgetMiddleware is now attached in
build_subagent_runtime_middlewares so the cost-ceiling backstop engages for
every subagent. The hard-stop does not raise — it strips tool_calls and
lets the run finish with a final answer, recording the cap on a per-run
consume_stop_reason() accessor.
- executor.py: on normal completion it reads consume_stop_reason() and stamps
completed + token_capped when the budget fired; on GraphRecursionError it
recovers the last AIMessage partial (completed + turn_capped) or, if nothing
usable survived, failed + turn_capped. SubagentResult gains stop_reason.
- status_contract.py / contracts/subagent_status_contract.json (v2) /
frontend subtask-result.ts: additive subagent_stop_reason field, pinned by
test_status_values_match_contract / test_stop_reason_values_match_contract.
- task_tool.py + delegation_ledger.py: drop the max_turns_reached paths; the
ledger captures stop_reason and renders model-facing "capped" guidance so
the lead reuses a capped completion knowingly.
The 2,000,000-token default is deliberately loose (tighten to taste) — it
would have roughly halved the reported 4.4M burn while leaving legitimate
deep-research runs (max_turns=150) room. Subagent summarization is a follow-up.
* fix(subagents): surface turn-budget cap as MAX_TURNS_REACHED with partial result (#3875)
Phase 2 of #3875. When a subagent exhausts its turn budget
(recursion_limit == max_turns), LangGraph raises
GraphRecursionError from agent.astream. The generic
except Exception in _aexecute misclassified it as FAILED and
discarded the partial work already streamed into final_state, so the
lead could not tell 'broken subagent' from 'out of budget' and got an
empty failure.
Catch GraphRecursionError specifically (before the generic handler)
and set a distinct SubagentStatus.MAX_TURNS_REACHED terminal status,
recovering the partial result from the last streamed chunk via a shared
_extract_final_result helper (refactored out of the normal-completion
path so both paths render content identically).
Extend the cross-language status contract so the new value travels on
additional_kwargs.subagent_status: a capped run is result-bearing, so
make_subagent_additional_kwargs / read_subagent_result_metadata
carry subagent_result_brief + subagent_result_sha256 (the
recovered work, like completed) AND the cap notice on subagent_error
-- the one status that carries both. task_tool.py returns it via the
shared _task_result_command; the delegation ledger prefers the
partial result_brief and renders model-facing guidance (reuse / retry
tighter / raise max_turns). Frontend collapses max_turns_reached to the
failed pill with the cap notice on error.
No agent-loop, runner, or persistence behavior touched; default
max_turns is unchanged.
* refactor(subagents): consolidate content-stringify onto shared helper
Address review feedback on #3949 (willem-bd, copilot-pull-request-reviewer):
- executor.py: drop the private `_stringify_message_content` — a third
near-duplicate of `utils/messages.py::message_content_to_text`.
`_extract_final_result` now delegates to that canonical helper; the
"No response generated" sentinel is pushed down to the consumer (the
shared helper returns "" for no-text, matching every other call site).
- task_tool.py: align the live `task_failed` event's error string with
the canonical "Reached max_turns=N" used by the logger, the structured
`error=`, and the executor (was "Reached max turns (N)").
Behavior for real AIMessage content is unchanged; only atypical edge inputs
(consecutive bare-string list items; empty content) now match the canonical
helper that every other call site already uses.
`extract_response_text` is intentionally left as-is: it filters by OpenAI
content-block `type`, a different shape with many callers and its own tests.
Co-Authored-By: Claude <noreply@anthropic.com>
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Co-authored-by: Claude <noreply@anthropic.com>
* feat: emit structured runtime metadata
* fix: avoid subagent import cycle in replay gateway
* fix: preserve legacy subtask result parsing
* refactor: tighten runtime metadata contracts
* fix(middleware): keep recovery hint on task exception wrapper content
The structured-metadata stamp overwrote the wrapper text with the bare
task-failure message, dropping the model-facing 'Continue with available
context, or choose an alternative tool.' guidance that every other tool
exception keeps. Append the shared hint after the formatted message.
* fix(subagents): require lowercase hex for result_sha256 reader
Length-only validation accepted any 64-char string; a faulty serializer
or relaying wrapper could store a non-digest value in the delegation
ledger. Enforce the producer's hexdigest shape with a fullmatch.
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
* feat(subagents): add delegations ledger field + reducer to ThreadState
* feat(subagents): pure helpers to derive + format the delegation ledger
* feat(subagents): DelegationLedgerMiddleware records + injects the ledger
* feat(subagents): register DelegationLedgerMiddleware for lead when subagents enabled + docs
* add runtime log
* chore(subagents): make delegation-ledger injection log production-ready
* test(subagents): make delegation-ledger registration tests config-free; refresh ultra replay golden for delegations channel
* refactor(subagents): derive TERMINAL_STATUSES from SUBAGENT_STATUS_VALUES + pin it
Make thread_state's TERMINAL_STATUSES a frozenset over the status contract's
SUBAGENT_STATUS_VALUES instead of a hardcoded literal, so the terminal-status
set can never drift from the contract. Add a pinning test asserting the
derivation and that the non-terminal "in_progress" stays excluded.
Addresses PR #3877 review.
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
