Sanitize null `tool_calls[].type` in proxied chat history for GPT-5.4 by Copilot · Pull Request #3101 · github/gh-aw-firewall

Copilot · 2026-05-13T13:43:41Z

Bug Fix

What was the bug?

GPT-5.4 requests coming from Copilot CLI could include prior messages with tool_calls[].type = null (notably after edit-tool turns), which OpenAI rejects with HTTP 400 (expected 'function'|'alltools'|'custom'). Retry logic could not recover because the same poisoned history was resent.

How did you fix it?

Request-history sanitization in API proxy
- Added a targeted sanitizer in containers/api-proxy/proxy-request.js that runs on outbound JSON bodies for POST/PUT/PATCH.
- For each messages[*].tool_calls[*]:
  - type: null + valid function payload → normalize to type: "function".
  - type: null without usable function payload → drop malformed entry.
Behavioral guardrails
- No-op for non-JSON payloads and requests without messages.
- Leaves already-valid tool calls untouched.
Regression coverage
- Extended containers/api-proxy/server.proxy.test.js with focused cases for:
  - null-type normalization path
  - malformed null-type drop path

if (Object.hasOwn(toolCall, 'type') && toolCall.type === null) {
  if (toolCall.function && typeof toolCall.function === 'object') {
    nextToolCalls.push({ ...toolCall, type: 'function' });
  } else {
    // drop malformed entry
  }
}

Testing

Added regression tests asserting forwarded request bodies are sanitized before upstream dispatch for both:

null -> "function" normalization
malformed null-type tool-call removal

github-actions · 2026-05-13T14:27:20Z

Smoke Test Results

❌ GitHub API: Failed (auth not available in this environment)
✅ Playwright: Passed (GitHub.com title contains "GitHub")
✅ File verify: Passed (marker file exists with timestamp)

Total: 2/3 PASS

💥 [THE END] — Illustrated by Smoke Claude

github-actions · 2026-05-13T14:28:18Z

Smoke Test: Codex

PRs reviewed: #3080 Remove dead __testing export from host-iptables public API; #3077 perf(export-audit): move phases 1–3 to pre-steps, cut ~75% token usage
GitHub PR review: ✅
SafeInputs GH: ❌ unavailable
Playwright GitHub title: ✅
Tavily search: ❌ no callable tools
File write/bash read/build: ✅
Discussion comment: ❌ tool unavailable
Overall status: FAIL

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

registry.npmjs.org

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "registry.npmjs.org"

See Network Configuration for more information.

🔮 The oracle has spoken through Smoke Codex

github-actions · 2026-05-13T14:28:22Z

Smoke Test: Copilot BYOK (Offline) Mode

Test	Result
1. GitHub MCP connectivity	❌ GitHub MCP returned 401 (unauthenticated)
2. GitHub.com HTTP connectivity	⚠️ No data (template vars not expanded)
3. File write/read	⚠️ No data (template vars not expanded)
4. BYOK inference (api-proxy → api.githubcopilot.com)	✅

Running in BYOK offline mode (COPILOT_OFFLINE=true) via api-proxy → api.githubcopilot.com.

Overall status: FAIL — pre-step template variables were not substituted; tests 1–3 could not be verified.

🔑 BYOK report filed by Smoke Copilot BYOK

github-actions · 2026-05-13T14:29:05Z

🧪 Smoke Test Results — Copilot Engine

Test	Result
GitHub MCP connectivity	❌ (401 auth error)
GitHub.com HTTP connectivity	✅
File write/read	✅ (`smoke-test-copilot-25803492205.txt` verified)

Overall: FAIL — MCP tool returned 401 on PR list query.

PR triggered by @lpcox. No assignees detected.

📰 BREAKING: Report filed by Smoke Copilot

Copilot

Pull request overview

Fixes a proxying bug where Copilot CLI chat history could include messages[].tool_calls[].type = null, causing upstream OpenAI-compatible endpoints (e.g., GPT-5.4) to reject requests with HTTP 400 and making retries ineffective.

Changes:

Added request-body sanitization in the API proxy to normalize tool_calls[].type: null to "function" when a function payload exists, otherwise dropping malformed tool calls.
Added regression tests ensuring the proxied outbound body is sanitized before upstream forwarding.

Show a summary per file

File	Description
containers/api-proxy/proxy-request.js	Adds outbound JSON-body sanitization for null `tool_calls[].type` and logs normalization/drop counts.
containers/api-proxy/server.proxy.test.js	Extends proxy request tests to assert normalization and malformed-entry dropping behavior.

Copilot's findings

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Files reviewed: 2/2 changed files
Comments generated: 1

+    if (req.method === 'POST' || req.method === 'PUT' || req.method === 'PATCH') {
+      const sanitized = sanitizeNullToolCallTypes(body);
+      if (sanitized) {
+        body = sanitized.body;
+        logRequest('info', 'request_sanitized', {
+          request_id: requestId,
+          provider,
+          normalized_tool_calls: sanitized.normalizedCount,
+          dropped_tool_calls: sanitized.droppedCount,
+        });
+      }
+    }


github-actions · 2026-05-13T14:30:08Z

Smoke Test Results\n\n- GitHub MCP Testing: ❌ (mcpscripts command not found)\n- GitHub.com Connectivity: ❌ (SSL error 35)\n- File Writing Testing: ✅\n- Bash Tool Testing: ✅\n\nOverall status: FAIL

Warning

Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

localhost

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "localhost"

See Network Configuration for more information.

💎 Faceted by Smoke Gemini

github-actions · 2026-05-13T14:30:40Z

🏗️ Build Test Suite Results

Ecosystem	Project	Build/Install	Tests	Status
Bun	elysia	✅	1/1 passed	✅ PASS
Bun	hono	✅	1/1 passed	✅ PASS
C++	fmt	✅	N/A	✅ PASS
C++	json	✅	N/A	✅ PASS
Deno	oak	N/A	1/1 passed	✅ PASS
Deno	std	N/A	1/1 passed	✅ PASS
.NET	hello-world	✅	N/A	✅ PASS
.NET	json-parse	✅	N/A	✅ PASS
Go	color	✅	1/1 passed	✅ PASS
Go	env	✅	1/1 passed	✅ PASS
Go	uuid	✅	1/1 passed	✅ PASS
Java	gson	✅	1/1 passed	✅ PASS
Java	caffeine	✅	1/1 passed	✅ PASS
Node.js	clsx	✅	All passed	✅ PASS
Node.js	execa	✅	All passed	✅ PASS
Node.js	p-limit	✅	All passed	✅ PASS
Rust	fd	✅	1/1 passed	✅ PASS
Rust	zoxide	✅	1/1 passed	✅ PASS

Overall: 8/8 ecosystems passed — ✅ PASS

Generated by Build Test Suite for issue #3101 · ● 4.9M · ◷

github-actions · 2026-05-13T14:30:43Z

Smoke Test Results

Redis PING: ❌ (no response)
PostgreSQL pg_isready: ❌ (no response)
PostgreSQL SELECT 1: ❌ (no response)

Overall: FAIL — host.docker.internal unreachable on both ports 6379 and 5432.

🔌 Service connectivity validated by Smoke Services

github-actions · 2026-05-13T14:33:01Z

Chroot Smoke Test Results

Runtime	Host Version	Chroot Version	Match?
Python	Python 3.12.13	Python 3.12.3	❌
Node.js	v24.14.1	v20.20.2	❌
Go	go1.22.12	go1.22.12	✅

Overall: FAILED — Python and Node.js versions differ between host and chroot environment.

Tested by Smoke Chroot

Initial plan

d5b66ba

Copilot AI assigned Copilot and lpcox May 13, 2026

Copilot started work on behalf of lpcox May 13, 2026 13:43 View session

Copilot AI linked an issue May 13, 2026 that may be closed by this pull request

[awf] copilot-harness: GPT-5.4 edit tool fails with null tool_call type (400 error) #3082

Closed

Copilot AI added 2 commits May 13, 2026 13:49

fix: sanitize null tool call types

e5fbb63

refactor: address proxy review notes

2af8be9

Copilot AI changed the title ~~[WIP] Fix null tool call type error in GPT-5.4 edit tool~~ Sanitize null tool_calls[].type in proxied chat history for GPT-5.4 May 13, 2026

Copilot finished work on behalf of lpcox May 13, 2026 13:53

Copilot AI requested a review from lpcox May 13, 2026 13:53

lpcox marked this pull request as ready for review May 13, 2026 14:24

lpcox requested a review from Mossaka as a code owner May 13, 2026 14:24

Copilot AI review requested due to automatic review settings May 13, 2026 14:24

Copilot started reviewing on behalf of lpcox May 13, 2026 14:25 View session

github-actions Bot mentioned this pull request May 13, 2026

[aw] No-Op Runs #2911

Open

github-actions Bot mentioned this pull request May 13, 2026

[aw] Smoke Codex failed #3107

Closed

Copilot AI reviewed May 13, 2026

View reviewed changes

github-actions Bot added the build-test label May 13, 2026

lpcox merged commit 16dd904 into main May 13, 2026
67 of 74 checks passed

lpcox deleted the copilot/fix-null-tool-call-type-error branch May 13, 2026 14:56

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Sanitize null `tool_calls[].type` in proxied chat history for GPT-5.4#3101

Sanitize null `tool_calls[].type` in proxied chat history for GPT-5.4#3101
lpcox merged 3 commits into
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copilot/fix-null-tool-call-type-error

Copilot AI commented May 13, 2026 •

edited

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Copilot AI commented May 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Bug Fix

What was the bug?

How did you fix it?

Testing

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github-actions Bot commented May 13, 2026

Smoke Test Results

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github-actions Bot commented May 13, 2026

Smoke Test: Codex

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Smoke Test: Copilot BYOK (Offline) Mode

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🧪 Smoke Test Results — Copilot Engine

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Pull request overview

Copilot's findings

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github-actions Bot commented May 13, 2026

Smoke Test Results\n\n- GitHub MCP Testing: ❌ (mcpscripts command not found)\n- GitHub.com Connectivity: ❌ (SSL error 35)\n- File Writing Testing: ✅\n- Bash Tool Testing: ✅\n\nOverall status: FAIL

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🏗️ Build Test Suite Results

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Smoke Test Results

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github-actions Bot commented May 13, 2026

Chroot Smoke Test Results

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Copilot AI commented May 13, 2026 •

edited

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