Summary

• Problem: (1) createGoogleThinkingPayloadWrapper applied unconditionally to all providers but only guarded for google-generative-ai, causing Cannot convert undefined or null to object crashes when google-vertex models were used via embedded runner. (2) The gaxios library dynamically imports node-fetch on Node 22+/24+/25 where native globalThis.fetch is available, causing auth-stack crashes in the Google Vertex pipeline.
• Why it matters: Both issues independently cause hard crashes for any user running google-vertex models, making the Vertex integration unusable on modern Node versions.
• What changed: (1) The thinking payload wrapper now short-circuits for non-Google API types and applies sanitization to both google-generative-ai and google-vertex. (2) Added a postinstall script (scripts/patch-gaxios-fetch.mjs) that patches gaxios to prefer globalThis.fetch before falling back to node-fetch. (3) Added regression tests for both fixes.
• What did NOT change (scope boundary): Transient error handling, retry logic, other provider streamFn chains, and the sanitization logic itself are unchanged.

Change Type (select all)

• Bug fix

Scope (select all touched areas)

• Skills / tool execution
• Integrations

Linked Issue/PR

• Closes google-vertex provider: Cannot convert undefined or null to object in streamFn creation #33392
• Fixes [Bug]: Vertex embedded runs fail with "Cannot convert undefined or null to object" on v2026.3.1 (Telegram + cron) #32245
• Related [Bug]: googlechat broken in 2026.3.3 #33256, [Bug]: googlechat not starting with error "failed (unknown) - Cannot convert undefined or null to object" #33468

User-visible / Behavior Changes

• Google Vertex models no longer crash with Cannot convert undefined or null to object when used via the embedded runner.
• The gaxios auth stack no longer fails on Node 22+/24+/25 due to broken node-fetch dynamic import.

Security Impact (required)

• New permissions/capabilities? No
• Secrets/tokens handling changed? No
• New/changed network calls? No
• Command/tool execution surface changed? No
• Data access scope changed? No

Repro + Verification

Environment

• OS: macOS
• Runtime/container: Node 22+
• Model/provider: google-vertex / Gemini 3.1
• Integration/channel (if any): N/A
• Relevant config (redacted): N/A

Steps

1. Configure a google-vertex model (e.g. gemini-3.1-pro-preview)
2. Send a message through the embedded runner
3. Observe the crash in the thinking payload wrapper and/or gaxios auth stack

Expected

Message processes without errors; thinking payload is sanitized correctly for google-vertex.

Actual (before fix)

Cannot convert undefined or null to object crash from either the payload wrapper (spreading undefined options) or the gaxios auth stack (node-fetch import failure).

Evidence

• Failing test/log before + passing after

 ✓ src/agents/pi-embedded-runner-extraparams.test.ts (49 tests) 6ms
 ✓ src/infra/gaxios-fetch-regression.test.ts (1 test) 9ms

 Test Files  2 passed (2)
      Tests  50 passed (50)

Full suite: 6484+ tests passed.

Human Verification (required)

• Verified scenarios: Local test suite passes (pnpm build && pnpm check && pnpm test)
• Edge cases checked: google-vertex with negative thinkingBudget, non-Google API passthrough, gaxios fetch fallback on native-fetch Node
• What you did not verify: Live integration testing with real Google Vertex API credentials

Note: This PR was created with AI assistance (Claude Code). The code changes have been reviewed and understood.

Compatibility / Migration

• Backward compatible? Yes
• Config/env changes? No
• Migration needed? No

Failure Recovery (if this breaks)

• How to disable/revert this change quickly: git revert <commit-hash>
• Files/config to restore: src/agents/pi-embedded-runner/extra-params.ts, package.json, remove scripts/patch-gaxios-fetch.mjs
• Known bad symptoms reviewers should watch for: If the postinstall patch fails silently, gaxios would remain unpatched — symptom is the original auth crash on Node 22+.

Risks and Mitigations

• Risk: The gaxios postinstall patch modifies built artifacts inside node_modules; future gaxios updates may change the patched code patterns.
• Mitigation: The patch script detects if the pattern is already fixed or missing and logs the outcome. If gaxios ships a native fix, the patch becomes a no-op.