fix(agent_loop): nudge when a text-dialect tool block is claimed but undecodable - #224
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…undecodable A grammar that claims a <tool_call> block it cannot decode reports ParseDiagnostic::MalformedBlock; the stream scrubber removes the block from the visible text and yields no call. DeltaScrubber dropped those diagnostics and recover_text_calls returned before logging them, so the loop saw only the lead-in prose and ended the turn on it. The dropped-call nudge could not help: it keys on finish_reason == "tool_calls", which a text dialect never reports. Count MalformedBlock in both the scrubber and recover_text_calls, log it, and under a text dialect treat a count above zero as a dropped call on the existing dropped_tool_call_nudges budget, with a nudge that says the block could not be parsed. Refs tinyhumansai/openhuman#6723
Tiny Sweeper review
Last completed reportTiny Sweeper reviewThis pull request fixes a bug where a text-dialect tool block that a grammar claims but cannot decode (malformed) is silently dropped, causing the loop to treat the remaining prose as a final answer instead of nudging the model to re-issue the call. The fix introduces a malformed-block counter shared between the scrubber and recovery path, adjusts the nudge condition to fire for text dialects with undecoded blocks, and adds dedicated nudges and logging. State: Incomplete Review snapshot
Completeness: Incomplete What changedPreviously, when a model response under a text dialect contained a tool-call block that could not be parsed into a valid call, the block was scrubbed from the visible text and yielded no call, leaving only lead-in prose. The agent loop saw no tool calls and an early finish reason, so it ended the turn without re-prompting the model. Now the scrubber and the batch recovery path count how many blocks were malformed (`malformed` atomic counter on `TextRecovery`), and the loop condition treats a forced-text-dialect turn with malformed blocks the same as a dropped native call when tool calls are empty and tools were available. A custom nudge message explains the parse failure, and the re-prompt is bounded by the existing `dropped_tool_call_nudges` budget. Features
TestsNo supported feature-to-test mapping was produced. Test execution is not inferred.
Findings
Resolved this pass
Could not review: tinysweeper/tests Before merge
How this fits togetherflowchart LR
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n2["...lect_preserves_a_forced_named_tool_choice"]:::impacted
n3["...t_preserves_a_forced_required_tool_choice"]:::impacted
n4["..._code_calls_with_signatures_in_the_prompt"]:::impacted
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Agent review detailscritique
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Navigate logical layers of code changes, visualize relationships, and explore their blast radius. 📝 WalkthroughWalkthroughThe agent loop now counts malformed text-dialect tool-call blocks. When recovery detects malformed blocks, the loop can send a parsing-specific nudge and retry within its configured limit. Integration tests cover streaming and non-streaming behavior. ChangesText-Dialect Recovery
Priority: ⬇️ Low Estimated code review effort: 3 (Moderate) | ~20 minutes Change: Bug fix Sequence Diagram(s)sequenceDiagram
participant Model
participant DeltaScrubber
participant AgentLoop
Model->>DeltaScrubber: Send streamed delta
DeltaScrubber->>AgentLoop: Record malformed-block count
AgentLoop->>Model: Send parsing-specific nudge
Model->>AgentLoop: Return retry response
Suggested reviewers: Merge Risk: 🟡 Moderate · up to With empty-response retries enabled and a two-call limit, an undecodable tool block may never receive the intended correction prompt. Resolve the retry ordering before merging. Security Architecture ReviewSecurity architecture risk: 🔵 Low · up to The new recovery path is bounded and does not execute malformed tool calls. In an opt-in configuration, however, a blank malformed response can take a generic retry first, leaving no opportunity to send the intended parsing guidance when the call limit is tight. Retained concerns
Security review detailsSecurity Blast Radius
Trust Boundaries and Controls
Resilience and Maintainability Implications
Hardening Proposals
🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches 💡 1🛠️ Fix failing CI checks 💡
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Inline comments:
Review comments at @crates/tinyagents-harness/src/agent_loop/run_loop.rs:
- Around line 1542-1543: Update the response-handling flow around
`malformed_blocks` and `undecodable_text_call` so a scrubbed undecodable
tool-call block gets the parsing nudge before the empty-response retry path.
Check this case before the `nontruncated_empty` retry branch, or exclude it from
that branch, while preserving ordinary empty-response retries.
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crates/tinyagents-harness/src/agent_loop/dialect.rscrates/tinyagents-harness/src/agent_loop/run_loop.rscrates/tinyagents-integration-tests/tests/e2e_tool_dialects.rs
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Requesting changes: 1 lane(s) blocking, worst finding is high.
Fix or reply to the findings below and push. The next review clears this automatically once they are gone — you should not need to dismiss anything by hand.
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description: $0.0011 · 11,571 in / 4,904 out · 11,264 cached (97%) · deepseek/deepseek-v4-flash
tinysweeper
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Review at 1. Counter scope per attempt: correct across iterations; one edge inside an iteration. 2. No nudge when any call parsed: yes, gated on 3. Shared budget: both nudges increment the same per-run 4. Stream cut mid-block: not counted, and I think it should be. I probed
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…er text recovery Follow-ups to the undecodable-block nudge from review: - Dropped-block counts now describe only the response a base model call returns: cleared before the call (a cache hit makes no attempt) and again when it fails, so a wrap middleware that answers in place of a failed streamed attempt is not nudged for that attempt's block. - A block the model stopped inside without a closer (UnterminatedBlock, whose raw markup is released as visible text) counts as a dropped call unless the stop was a length cut, which stays with truncation handling. - The nudge also fires when text recovery is enabled for a native model, which parses the same grammars out of its prose. Refs tinyhumansai/openhuman#6723
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tinysweeper found nothing blocking, but could not review everything, so this is not an approval: tinysweeper/tests.
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done
…humansai#6723) Brings in tinyhumansai/tinyagents#223 (replay boundary, merged as fefbd11b; tree identical to the previously pinned b8b08187) and tinyhumansai/tinyagents#224 (text-dialect undecodable-block nudge, tinyhumansai#6723). No nested submodule moves.
1 participant
Refs tinyhumansai/openhuman#6723
Problem
Under a text tool-call dialect (xml / P-Format), a
<tool_call>block that atinytools-agentgrammar claims but cannot decode behaves like this: the stream scrubber removes it from the visible text, it yields zero calls, and it reportsParseDiagnostic::MalformedBlock. That diagnostic went nowhere:DeltaScrubber::feed/flushcollectedstep.callsand droppedstep.diagnostics.recover_text_callsreturned on "no calls" before its diagnostics loop, so nothing was logged even at debug.finish_reason == "tool_calls". A text dialect always reportsstop, so on this path the nudge could never fire.The loop saw only the lead-in prose ("Let me search for …") and took it as the turn's final answer. In the production thread behind openhuman#6723, this pattern ended most of 15 no-call turns, and the user had to send "?" 11 times.
Change
dialect.rsTextRecoverycarries amalformedcounter.DeltaScrubberadds to it from bothfeedandflush, and logs[agent_loop] scrubbed tool-call block(s) that did not decode into a callwith the count.recover_text_callsnow logs diagnostics before the empty-calls return, and returns its malformed count.run_loop.rsrecover_text_dialect_callsadds the batch count to the counter and logs it.finish_reason == "tool_calls" || (text dialect && malformed > 0). It is still insidetool_calls.is_empty(), so a response with one good call and one malformed call is not nudged. It is still bounded bydropped_tool_call_nudges.Why the scrubber needs its own counter. On a streamed call the scrubber removes the block before the terminal response is assembled. By the time the batch
recover_text_callsruns inrun_loop, the text no longer contains the block, so the batch parse cannot see it. Counting only inrecover_text_callswould cover the unary path and miss every streamed response. The second revert-check below shows this.Tests (
tinyagents-integration-tests/tests/e2e_tool_dialects.rs)The fixture is
<tool_call>not a call at all</tool_call>: claimed by the tagged grammar and not decodable by any grammar.an_undecodable_text_dialect_call_is_nudged_instead_of_ending_the_turn(unary)model_calls == 3,tool_calls == 1, nudge text in request 2a_streamed_undecodable_text_dialect_call_is_nudged_within_the_budget(realStreamingMockdeltas)model_calls == 4(bounded by the budget)a_decodable_or_plain_text_dialect_reply_is_not_nudged(control)model_calls == 2, no request contains the nudgeRevert-checks, run on this commit:
model_callsassertions (left 1 vs 3 / 4). The turn ends on the prose, which is the bug. The control stays green.fetch_addremoved: only the streamed test fails (left 1 vs 4).Lanes run locally:
cargo fmt --all -- --check;cargo clippy -p tinyagents-harness -p tinyagents-integration-tests --all-targets -- -D warnings;e2e_tool_dialects(26/26);tinyagents-harness --lib agent_loop(234 passed). See the follow-ups section for the wider run.Follow-ups from review (02a1176)
a_failed_attempts_undecodable_block_does_not_nudge_the_answer_that_replaced_it.tinytoolsreports a block with no closer asUnterminatedBlockon flush, notMalformedBlock, and releases the raw markup as visible text. The loop now counts it as a dropped call unlessfinish_reason == "length": a length cut is truncation and stays with truncation handling. Tests:a_stream_that_stops_inside_a_call_block_is_nudged; controla_length_cut_inside_a_call_block_is_left_to_truncation_handling.(text dialect || text_dialect_recovery_enabled) && dropped > 0. When recovery resolves off (Auto on a tool-calling profile), no text calls are parsed and nothing is nudged; that is the separate openhuman#6562 decision. Test:an_undecodable_block_under_native_text_recovery_is_nudged.an_undecodable_block_is_nudged_before_an_empty_response_retry. It cannot pre-empt today, because a fully-scrubbed stream keeps its raw terminal text.warnlog; there is no nudge, because the gate sits insidetool_calls.is_empty().Each fix was revert-checked on its own, and each revert fails only its own test. Lanes: fmt; clippy (
-p tinyagents-harness -p tinyagents-integration-tests --all-targets -D warnings);tinyagents-integration-testsin full (97 test binaries ok);tinyagents-harness --lib(1366 passed).Notes
RUSTDOCFLAGS="-D warnings" cargo doc -p tinyagents-harnesserrors on a private intra-doc link atcrates/tinyagents-harness/src/tool/toolset/mod.rs:175(ToolRegistry::model_dispatch). CI's doc step does not set-D warnings. This change adds no rustdoc warnings.tinytools-agentelement grammar (the<todo><todos>…</todos></todo>call shape) emitsMalformedBlock { source: CallSource::Element, .. }for a block it claims but cannot decode. The counter matchesMalformedBlock { .. }with any source, so that shape is covered once the tinytools bump lands. Blocks that grammar does not claim stay visible, so none of them are swallowed silently.CI note: tinysweeper/tests skipped (bot reported "No reviewer could be consulted"); advisory, not required; the 8 tests are listed above.