fix(ai): dedupe duplicate tool_results after compaction/batch (non-retryable 400)

[ocervell]

Bug (hit during CLI testing, after compaction)

[WRN] Chat history trimmed: dropped 10 messages to fit under 100000 tokens.
[ERR] LLM call failed with non-retryable 400: ... each tool_use must have a single result.
      Found multiple `tool_result` blocks with id: toolu_bdrk_01Bi8...

Providers fold consecutive tool messages into a single user turn and reject more than one tool_result per tool_use id — a non-retryable 400 that aborts the whole run.

Root cause

_dispatch_and_collect grouped batch results with itertools.groupby, which groups only consecutive equal keys. In batch mode (_run_batch) results interleave by tool_call_id (e.g. [X, Y, X]), so groupby produced several groups for one id → add_tool_result fired more than once for it → duplicate consecutive tool messages → litellm folds them into one user turn with duplicate tool_result blocks → 400. History trim/compaction restructures the window the same way (hence the correlation with compaction).

Fix (source + safety net)

1. Order-preserving grouping — group collected by an ordered dict instead of groupby, so each tool_call_id yields exactly one result regardless of arrival order (also fixes token accounting for interleaved batches).
2. _dedupe_tool_results in _repair_orphan_tool_uses — within each run of consecutive tool messages, keep the first result per id, drop the rest. Runs proactively before every LLM call and on the 400-repair-retry path, so the "multiple tool_result blocks" 400 is now repaired + retried instead of failing fast.

Tests

TestDedupeToolResults (drop consecutive dup, no-op when unique, per-run scoping, repair integration) + call_llm duplicate-400 → repaired-and-retried. Full AI suite: no new failures vs branch baseline.

Targets ai-resiliency (#1241).

🤖 Generated with Claude Code

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