* fix(stream): don't report dropped mid-tool-call streams as output truncation
A streaming tool call whose SSE ends with no finish_reason (the upstream
delivers the tool name + opening '{' then closes the connection cleanly,
no terminator, no [DONE]) was stamped finish_reason='length' by the mock
builder. That routed it through the output-cap truncation path: 3 useless
max_tokens-boosted retries, then the misleading 'Response truncated due to
output length limit' error — even though the model never reported hitting
any cap.
Reproduced live on nvidia/nemotron-3-ultra:free via the Nous dedicated
endpoint, which stalls/drops during large tool-arg generation (50s-4m41s).
Now: when tool args are incomplete AND the provider sent no finish_reason,
tag the response as a partial-stream stub so the loop reports an honest
mid-tool-call drop and asks the model to chunk its output (existing
continuation machinery), instead of escalating output budget and lying.
A provider-reported finish_reason='length' still takes the real-truncation
path unchanged.
* test(stream): update truncated-tool-args test for drop-vs-cap split
test_truncated_tool_call_args_upgrade_finish_reason_to_length pinned the
old behaviour where ANY incomplete tool args → finish_reason='length' with
tool_calls preserved. That single-chunk-no-finish_reason scenario is exactly
the mid-tool-call stream drop now reclassified as a partial-stream stub.
Split into two tests matching the new contract:
- no finish_reason + incomplete args → PARTIAL_STREAM_STUB_ID, tool_calls=None,
_dropped_tool_names set (the drop path)
- explicit finish_reason='length' + incomplete args → tool_calls preserved,
'length' upgrade unchanged (the genuine output-cap path)
* fix(streaming): route mid-tool-call partial-stream-stub through length continuation (#31998)
When a stream stalls mid-tool-call (e.g. a large write_file), the
partial-stream-stub recovery used finish_reason='stop' which caused the
conversation loop to treat the turn as complete, returning only the
warning text. When users said 'continue', the model retried the same
large tool call, hit the same stale timeout, and looped indefinitely.
Changes:
- chat_completion_helpers.py: change _stub_finish_reason from 'stop' to
'length' for mid-tool-call partials. The stub still has tool_calls=None
so no tool auto-executes — the model gets a fresh API call through the
existing length-continuation machinery (bounded to 3 retries).
Also attach _dropped_tool_names to the stub for downstream use.
- conversation_loop.py: add a third continuation prompt branch for
partial-stream-stubs with dropped tool calls. Instead of the generic
'continue where you left off' (which would retry the same large call),
tell the model to break the output into smaller tool calls (~8K
tokens each) to avoid stream timeouts.
- test_partial_stream_finish_reason.py: update existing test from
finish_reason='stop' to 'length', add _dropped_tool_names assertion,
add new test_dropped_tool_call_uses_chunking_prompt for the 3-way
prompt branching.
Safety: tool_calls=None is preserved on the stub, so the conversation
loop enters the text-continuation branch (line 1513), NOT the tool-call
execution branch (line 3246). No tool auto-executes. The model simply
gets another API call with targeted guidance.
* refactor: extract constants and continuation prompt helper
- Move magic strings to hermes_constants.py (PARTIAL_STREAM_STUB_ID,
FINISH_REASON_LENGTH)
- Extract _get_continuation_prompt() in conversation_loop.py — DRYs the
3-way prompt branching and lets tests import the real function
- Trim verbose inline comments in chat_completion_helpers.py
- Tests import constants + helper instead of duplicating logic
---------
Co-authored-by: alt-glitch <balyan.sid@gmail.com>
Three test classes lock in the #30963 fix:
1. TestPartialStreamStubFinishReason — drives _interruptible_streaming_api_call
through the two recovery branches and asserts:
- text-only partial → finish_reason="length" (the new behaviour),
- mid-tool-call partial → finish_reason="stop" (unchanged on purpose).
2. TestLengthContinuationPromptBranching — pure-Python check on the branch
that picks the continuation prompt by response.id. Locks the network
error wording for partial-stream-stub vs. the output-length wording
for everything else.
3. TestConversationLoopPartialStreamContinuation — feeds a stub +
continuation pair into run_conversation, verifies the loop makes a
second API call (instead of exiting with text_response(stop)),
confirms the network-error continuation prompt actually reaches the
model on call #2, and that final_response stitches both halves.
Refs: NousResearch/hermes-agent#30963
