Expose an optional protocol-aware LLM completion cap

[xeonvs]

Problem

OCR 1.9.10 sends its embedded completion cap of 58888 on full OpenAI Chat Completions review requests. Some compatible gateways reserve spend from the requested output cap and reject a full review before generation even when short probes succeed. OCR 1.9.10 has no public completion-cap setting, while its private llm.extra_body overlay can replace the protocol-specific wire field.

Implementation checklist

• Add optional OCR_LLM_MAX_COMPLETION_TOKENS; exact default is unset and inherits the qualified OCR behavior.
• Accept only a positive decimal integer from 1 through 1000000, with length bounded before conversion.
• Map openai to max_completion_tokens, openai-responses to max_output_tokens, and anthropic to max_tokens.
• Preserve unrelated OCR_LLM_EXTRA_BODY; deduplicate an equal JSON integer and reject conflicting or non-integer ownership.
• Leave OCR prompt/context max_tokens, OCR_MAX_TOKENS_BUDGET, receipt v5, DLP, telemetry, outcomes, severity, findings, and approval unchanged.
• Do not derive the value from /models.max_completion_tokens.
• Checksum-verify official Darwin arm64 OCR 1.9.10 (c626347bafcdbf25cf058af403d16568a3a9ffa1814046ff7c9d1e6becaf60d2).
• Observe exact no-LLM production-config wire behavior: unset 58888, explicit 4096; remove every temporary probe artifact.
• Add environment, generated-config, compatibility, and installed wheel/sdist tests.
• Document exact default, protocol mapping, collision migration, the three token controls, spending reservation, /models non-claim, and the 4096 example.
• Add the separate 130.feature.md operator/agent-facing changelog fragment.
• Complete focused, full quality/coverage, Gitleaks, manifest/lock, Towncrier, reproducible package, Twine, and Python 3.12–3.14 install gates.

Release lifecycle

• Implemented and pushed at Draft PR Release 0.8.1: completion cap and safe provider failures #131 exact head 53c6374da216bf88aa27ba6dd146b3322d8c8463 (tree 25e4340ce9a076edc28e5412edd11de7ac876d76).
• All hosted checks pass on that exact head.
• Protected feature PR is reviewed and merged.
• TestPyPI development artifact is independently verified.
• Protected 0.8.1 release and external registry/GitHub/provenance reconciliation complete.

Related safe diagnostics: #129. Keep this issue open until stable reconciliation.

[github-actions]

Stable v0.8.1 delivery is verified by immutable release asset release-receipt.json in v0.8.1 (SHA-256 453d0522e9b23aa164fe14d68d1d945fade2bc6a40dd0c26aadb76edca775ad2).