fix(ai-gateway): preserve Gemini thought signatures

[chrarnoldus]

Summary

• normalize native Gemini thought text and signatures into OpenRouter reasoning_details
• restore google-gemini-v1 encrypted details to native thought_signature fields on follow-up requests
• replace mutually exclusive response-transform booleans with a single enum and retain legacy client signature support

Verification

• pnpm --filter web exec jest --runInBand --forceExit --runTestsByPath src/lib/ai-gateway/rewriteModelResponse.test.ts src/lib/ai-gateway/experiments/build-direct-provider.test.ts src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts src/lib/ai-gateway/providers/provider-definitions.test.ts 'src/app/api/openrouter/[...path]/route.test.ts' (180 tests passed)
• pnpm --filter web typecheck
• pnpm --filter web lint
• git diff --check

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (2 files)

• apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts
• apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts
• apps/web/src/lib/ai-gateway/reasoning-details-transform.ts

Previous Review Summary (commit 87774b5)

Current summary above is authoritative. Previous snapshots are kept for context only.

Previous review (commit 87774b5)

Status: 4 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	1
WARNING	3
SUGGESTION	0

Issue Details (click to expand)

CRITICAL

File	Line	Issue
packages/db/src/schema-types.ts	2062	Stored use_gemini_reasoning_transform configs are silently stripped

WARNING

File	Line	Issue
apps/web/src/lib/ai-gateway/reasoning-details-transform.ts	52	All Gemini reasoning blocks share index: 0, so clients concatenate/overwrite signatures
apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts	105	Id-less encrypted details attach to the first tool call
apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts	332	reasoning_effort is now read after remove_from_body

Files Reviewed (13 files)

• apps/web/src/app/api/openrouter/[...path]/route.test.ts - 0 issues
• apps/web/src/lib/ai-gateway/experiments/build-direct-provider.test.ts - 0 issues
• apps/web/src/lib/ai-gateway/experiments/build-direct-provider.ts - 0 issues
• apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts - 0 issues
• apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts - 2 issues
• apps/web/src/lib/ai-gateway/providers/openrouter/request-helpers.ts - 0 issues
• apps/web/src/lib/ai-gateway/providers/provider-definitions.test.ts - 0 issues
• apps/web/src/lib/ai-gateway/providers/provider-definitions.ts - 0 issues
• apps/web/src/lib/ai-gateway/providers/types.ts - 0 issues
• apps/web/src/lib/ai-gateway/reasoning-details-transform.ts - 1 issue
• apps/web/src/lib/ai-gateway/rewriteModelResponse.test.ts - 0 issues
• apps/web/src/lib/ai-gateway/rewriteModelResponse.ts - 0 issues
• packages/db/src/schema-types.ts - 1 issue

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_{Reviewed by grok-4.6 · Input: 97.3K · Output: 13.2K · Cached: 195.2K}

_{Review guidance: REVIEW.md from base branch main}