feat(cli): add an opt-in failure-taxonomy report categorizing tool-failure causes for unattended runs (#222)

[qwen-code-dev-bot]

Summary

Adds an opt-in (--failure-taxonomy) privacy-safe failure-taxonomy report for unattended (-p) runs, decomposed from roadmap #38 (observable autonomous execution).

The run summary (#40) reports a single terminal reason and counts tool failures by name, but not why each call failed — so operators triaging a failed run had to read raw logs to tell a policy denial from a hook denial, an approval denial, a path escape, or a tool error. This report categorizes each failed tool call into a fixed taxonomy and reports the terminal reason class.

Design

• New src/run-failure-taxonomy.ts: a FailureTaxonomyCollector accumulates per-cause failure counts into a fixed taxonomy (policy_denied, hook_denied, approval_denied, folder_trust_denied, path_escape, unknown_tool, tool_error, plus an other bucket); build emits a bounded report in canonical order with the terminal reason. Mirrors the run-summary.ts/run-bottleneck.ts schema and redaction conventions.
• src/agent.ts: executeToolCall records the cause at each failure branch (unknown tool, folder-trust, command policy, PreToolUse hook, approval), and categorizes a thrown error or returned isError result as path_escape (detected via a resolveSafe pre-check for mutate-file tools) or tool_error. Threaded through AgentOptions.
• src/headless-protocol.ts: new failure_taxonomy NDJSON event.
• src/index.ts: opt-in --failure-taxonomy flag wired into both the NDJSON and plain-text headless paths.

The report is metadata only — category names, counts, and the terminal reason. It has no channel for error text, prompts, file contents, secrets, or raw tool payloads.

Testing

• tests/unit/run-failure-taxonomy.test.ts (10 tests): per-cause counting, canonical ordering, other bucket, non-zero-only output, reason sanitization, empty inventory, formatting.
• tests/integration/run-failure-taxonomy.test.ts (5 tests): text/JSON emission, an unknown-tool failure categorized, a path-escape write categorized distinctly, secret-shaped arguments kept out of the report, zero-failure inventory.

Gates: typecheck, build, unit (1608), integration (+ desktop), smoke (51) all pass.

Closes #222

[qwen-code-dev-bot]

E2E verification

• Repository: qwen-code-dev-bot/oh-my-cli
• Pull request: #223
• Commit: 4e8910b2dd6440eb30e38ff487b6fd8385f1069f
• Evidence mode: terminal
• Result: PASS

Scenario	Command	Exit	Duration
integration	npm run test:integration	0	28.312s
smoke	npm run smoke	0	3.016s

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