[devteamaegis]

What's broken

When an InternLM2 model produces output with more than one <|action_start|><|plugin|> marker, both extract_tool_calls and extract_tool_calls_streaming crash:

ValueError: too many values to unpack (expected 2)

The crash happens at the lines text, action = text.split("< |action_start|><|plugin|>") in each method. If the delimiter appears more than once, split() returns 3+ items and the 2-variable unpack fails.

Why it happens

Both lines call str.split(delimiter) without a maxsplit argument. The code assumes the delimiter appears exactly once, but that assumption breaks as soon as the model emits a second tool-call block or repeats the marker.

Fix

Changed both calls to split("<|action_start|><|plugin|>", 1). This splits only on the first occurrence, keeping the behavior correct for single-marker output while no longer crashing on multi-marker output.

Test

Added test_multiple_action_start_markers_no_valueerror to tests/tool_parsers/test_internlm2_tool_parser.py. It passes a model output string containing two <|action_start|><|plugin|> markers to extract_tool_calls and asserts tools_called is True — confirming the parser returns a result instead of raising ValueError.

Fixes #44139

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[hclsys]

fix is right + minimal. one gap: the regression test covers run_tool_extraction_nonstreaming only, but you patched extract_tool_calls_streaming (line 80) too. the streaming path is where the second marker actually arrives in a separate chunk — worth adding a streaming-path test that feeds the two <|action_start|> markers in two separate deltas to exercise that branch and prove no ValueError there either.

minor nit (existing code, not your change): line 204 has action.split("<|action_end|>".strip()) — the .strip() is on the literal, not the result. harmless since the literal has no whitespace, but it reads like a bug. drive-by cleanup or leave.

[bbrowning]

Did you consider fixing the underlying issue so that both tool calls are properly extracted? Instead of fixing the ValueError but silently dropping the 2nd or later tool calls in the model output?

Do you have an example real-world request that you're using to reproduce and validate this fix?

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @devteamaegis.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[devteamaegis]

Thanks both — you're right.

@bbrowning: the split(..., 1) version stopped the crash but silently dropped the 2nd+ tool call, which is worse. I've reworked extract_tool_calls to split on all <|action_start|><|plugin|> markers and return a ToolCall per block, with leading text preserved as content; single-call / empty-args / plain-text / malformed inputs are unchanged. Repro: ...<|action_start|><|plugin|>{"name":"get_weather",...}<|action_end|><|action_start|><|plugin|>{"name":"get_time",...}<|action_end|> → old: ValueError; new: two tool calls. Being honest on the real-world question: the official InternLM2 template emits one tool call per turn, so multi-marker output isn't part of the normal protocol — it shows up when the model misbehaves (InternLM2 tool output is known to be unstable), so this is a robustness fix, but silently dropping data is worse than the crash.

@hclsys: added a streaming-path test feeding the two markers in separate deltas.

Two honest notes: (1) the branch is well behind main now and will need a rebase — happy to do that. (2) #48348 is touching this same parser for the adjacent 'whole tool call in one delta' streaming case; if you'd prefer these consolidated or think #48348 supersedes this, just say and I'll rebase accordingly or close.

[devteamaegis]

Closing this as it has gone stale. Happy to reopen and rebase if it's still useful. Thanks!