Shaojin Wen 519e5aa1de fix(core): recover from truncated tool calls via multi-turn continuation (#3313) ... * fix(core): recover from truncated tool calls via multi-turn continuation (#3049) When large tool calls (e.g., WriteFile with big HTML) exceed the output token limit, the model's response gets truncated and required parameters like file_path are missing. Previously this surfaced as a confusing "params must have required property" error. Three-layer defense: 1. Escalate to model's actual output limit (not fixed 64K). Models with 128K output (Claude Opus, GPT-5) now use their full capacity. 2. Multi-turn recovery: if the escalated response is still truncated, keep the partial response in history and inject a recovery message ("Resume directly — pick up mid-thought") so the model continues from where it left off. Up to 3 recovery attempts before falling back to the tool scheduler's guidance. 3. Stronger truncation guidance as fallback: "you MUST split" instead of "consider splitting". Also fixes: - Clear toolCallRequests on RETRY to prevent duplicate tool execution - Add isContinuation flag to RETRY events so the UI preserves text buffers during recovery (continuation) but resets them during escalation (fresh restart) - Catch errors during recovery to prevent dangling history entries * docs: update adaptive output token escalation design for recovery mechanism Update the design doc to reflect: - Escalation now targets model's actual output limit (64K floor) - Multi-turn recovery loop after escalation (up to 3 attempts) - isContinuation flag on RETRY events - Recovery error handling (pop dangling message, break) - Updated constants table and model-specific escalation limits - New design decision: why multi-turn recovery over progressive escalation * fix: remove competitor reference from code comment * fix: address review feedback on recovery mechanism Three correctness fixes from @tanzhenxin's review: 1. Partial text lost during continuation (useGeminiStream.ts): On continuation RETRY, setPendingHistoryItem(null) cleared the pending gemini item. The next Content event then saw a null pending item, created a fresh one, and reset geminiMessageBuffer = eventValue — discarding the preserved partial text. Now the pending item AND buffers are kept on continuation, so the continuation appends. 2. Recovery on truncated tool-call turns (geminiChat.ts): When the truncated turn already contains a complete functionCall, appending a user recovery message produces model(functionCall) → user(text) with no intervening functionResponse — an invalid API sequence. Now recovery skips turns with functionCall parts and defers to the tool scheduler's layer-3 fallback. 3. Recovery errors swallowed after partial chunks (geminiChat.ts): If a recovery attempt yielded chunks then failed, the catch block broke without emitting any terminal signal, leaving the UI with partial text and no Finished event. Now emits a synthetic finishReason=STOP chunk in the catch so the UI gets a proper terminal signal. * test: add coverage for output token recovery loop Four targeted tests for the recovery mechanism introduced in the truncated-tool-call-recovery PR: 1. Recovery loop fires when escalated response is also truncated: initial MAX_TOKENS → escalation MAX_TOKENS → recovery STOP. Verifies two RETRY events (one escalation, one continuation) and three API calls. 2. Recovery is skipped when truncated turn contains a functionCall: prevents the invalid model(functionCall) → user(text) sequence. Verifies no continuation RETRY and history ends with the functionCall intact. 3. Recovery attempts are capped at MAX_OUTPUT_RECOVERY_ATTEMPTS (3): persistent MAX_TOKENS triggers exactly 5 API calls (1 initial + 1 escalation + 3 recovery). 4. Recovery catch block emits synthetic STOP chunk and pops dangling user message: when a recovery attempt fails (empty stream → InvalidStreamError), the UI gets a terminal signal and history ends on the model turn, not a dangling user recovery message. * test: cover cross-iteration functionCall detection in recovery loop Existing tests cover the functionCall guard when both initial and escalated responses have functionCall. This adds a test for the cross-iteration case: iter 1 returns text (recovery proceeds), iter 2 returns functionCall (recovery must break before iter 3). Verifies: - API called exactly 4 times (1 initial + 1 escalation + 2 recovery) - History ends with the functionCall model turn, not a dangling user recovery message - Iter 3's user recovery message is never pushed (guard fires at top of loop before recoveryCount increment) * fix(core): cast synthetic STOP chunk via unknown for TS2352 The object literal {candidates, content, parts} doesn't structurally overlap enough with GenerateContentResponse for TypeScript's strict narrow cast. Casting through 'unknown' is required per TS2352. Build error from CI: src/core/geminiChat.ts(651,24): error TS2352: Conversion of type '...' to type 'GenerateContentResponse' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first. * test(core): tighten recovery history integrity assertions Strengthen the "pop dangling recovery message" test to catch any future regression that leaves consecutive same-role entries or an empty last-model placeholder in history — conditions providers reject on the next turn. * fix(core): coalesce recovery pairs to avoid leaking control prompt Previously every output-token recovery iteration left a (user, model) pair in durable history where the user turn was the internal OUTPUT_RECOVERY_MESSAGE control prompt. That prompt was then visible to every later turn, biasing responses and polluting compression, replay, and export. Track successful recovery iterations and, after the recovery loop, fold each completed pair back into the preceding model turn via a new `coalesceRecoveryPairs` helper. Failed iterations already pop their user turn in the catch block, so they need no coalescing. Adds a targeted test that runs escalation + two successful recovery iterations + a clean STOP, and asserts the merged history has exactly one user turn and one model turn, no trace of the control prompt text, and content ordered as B (escalation) + C + D.		2026-04-21 17:04:24 +08:00
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adaptive-output-token-escalation-design.md	fix(core): recover from truncated tool calls via multi-turn continuation (#3313)	2026-04-21 17:04:24 +08:00