Consolidate wazero guard runtime/module config and disable DWARF debug info by default by Copilot · Pull Request #11505 · github/gh-aw-mcpg

Copilot · 2026-08-19T13:56:32Z

The wazero module review flagged duplicated runtime/module construction across production and test code, and suggested disabling DWARF debug info for the production guard compiler since guard binaries are untrusted artifacts whose stack traces are never symbolicated.

Production (`internal/guard/wasm_lifecycle.go`)

Extracted newGuardRuntimeConfig(opts): compiler engine, WithCloseOnContextDone(true), WithMemoryLimitPages(guardMemoryLimitPages) (named constant replacing the inline 512), and the three-way compilation-cache selection (opt-out / injected / global).
Debug info is now disabled unless guard debug logging is on (WithDebugInfoEnabled(logWasm.Enabled())), so DWARF parsing cost is skipped in production while remaining available under DEBUG=guard:wasm.
Extracted newGuardModuleConfig(name, stdout, stderr) so the WithStartFunctions() suppression and stdin/stdout isolation guarantees are defined once.
Added getGlobalCompilationCache(), which reads the process-global cache under the existing mutex. Previously the cache was read unlocked while ConfigureGlobalCompilationCache / CloseGlobalCompilationCache could concurrently swap it.

runtimeConfig := wazero.NewRuntimeConfigCompiler().
    WithCloseOnContextDone(true).
    WithMemoryLimitPages(guardMemoryLimitPages).
    WithDebugInfoEnabled(logWasm.Enabled())

Tests

New wasm_testruntime_test.go provides newTestWasmRuntime, newTestWasmModuleConfig, instantiateTestWasmModule, and setupTestWasmGuard. The near-identical setupRawWasmModule / setupWasmGuard helpers and the inline interpreter constructions in wasm_test.go now route through them, removing the test/production config drift risk called out in the review.
New wasm_config_test.go covers module-name defaulting ("" → "guard") and instantiation through each cache-selection path of the runtime config builder.

Disk-backed caching (recommendation 3) is left as-is: it is already opt-in via MCP_GATEWAY_WASM_CACHE_DIR / ConfigureGlobalCompilationCache, and changing the default is a deployment-policy decision rather than a code fix.

Fixes [go-fan] Go Module Review: tetratelabs/wazero #11491

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot

Pull request overview

Consolidates wazero guard configuration to reduce drift and disable unnecessary DWARF processing by default.

Changes:

Centralizes production runtime, module, and cache configuration.
Adds shared WASM test helpers.
Adds coverage for module naming and cache-selection paths.

Show a summary per file

File	Description
`internal/guard/wasm_lifecycle.go`	Centralizes wazero configuration and synchronizes cache reads.
`internal/guard/wasm_testruntime_test.go`	Adds shared test runtime helpers.
`internal/guard/wasm_config_test.go`	Tests runtime and module configuration.
`internal/guard/wasm_test.go`	Adopts shared test helpers.
`internal/guard/wasm_dispatch_test.go`	Reuses centralized guard setup.
`internal/guard/wasm_parse_coverage_test.go`	Reuses centralized guard setup.

Review details

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Files reviewed: 6/6 changed files
Comments generated: 1
Review effort level: Balanced

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

lpcox · 2026-08-19T14:49:38Z

@copilot resolve the merge conflicts in this pull request

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot · 2026-08-19T14:57:30Z

@copilot resolve the merge conflicts in this pull request

Resolved the merge conflicts and pushed merge commit 1b011ef. Validation passed: go test ./internal/guard ./internal/config ./internal/cmd, CodeQL found 0 alerts, and make agent-finished completed successfully.

lpcox · 2026-08-19T15:04:06Z

@copilot fix the failing ci checks https://github.com/github/gh-aw-mcpg/actions/runs/32266659434/job/96113498889?pr=11505 https://github.com/github/gh-aw-mcpg/actions/runs/32266651262/job/96113486100?pr=11505

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot · 2026-08-19T15:11:46Z

@copilot fix the failing ci checks https://github.com/github/gh-aw-mcpg/actions/runs/32266659434/job/96113498889?pr=11505 https://github.com/github/gh-aw-mcpg/actions/runs/32266651262/job/96113486100...

Fixed in 3fed... — the lint failure was an unused newTestInterpreterRuntime helper left in internal/guard/wasm_test.go after consolidating test runtime construction into the new shared helpers; removed it and confirmed golangci-lint run is clean and make agent-finished passes.

The race-test failure (TestValidateAgainstCustomSchema_RemoteRefByteBudgetIsEnforced in internal/config) is unrelated to this PR — no commits here touch that file, and it passes consistently locally (10+ runs, with and without -race). This looks like CI flakiness; will keep an eye on the next run.

github-actions · 2026-08-19T15:21:04Z

🔒 mcpg Read-Only Stress — default

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: default AWF (normal container isolation)

Part	Surface	Op	Result	Expected	Status
A	MCP	reads (list_issues/prs/commits, get_file_contents)	data returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	tools absent from catalog	BLOCKED	⚠️
C	CLI	reads (list_issues, get_file_contents)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	gh unauthenticated	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	gh unauthenticated	BLOCKED	⚠️

Overall: INCONCLUSIVE

⚠️ Gaps:

Part B: All 7 write tools absent from the MCP catalog (backend launched with GITHUB_READ_ONLY=1). This confirms the gh-aw framework defense-in-depth, but the gateway's own independent DIFC/guard enforcement layer was not exercised — write tool calls never reached a write-capable backend. Reported as INCONCLUSIVE per methodology.
Parts D/E: gh CLI is not authenticated in this environment (no GH_TOKEN). The REST/GraphQL token-scope boundary could not be validated. All D/E rows are INCONCLUSIVE.

No writes leaked. No FAIL conditions observed.

References: §32268247381

🔒 mcpg read-only stress (default AWF runtime) by Read-Only Stress: default runtime

github-actions · 2026-08-19T15:21:42Z

🔒 mcpg Read-Only Stress — gVisor

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: gVisor (runsc) kernel-level isolation

Part	Surface	Op	Result	Expected	Status
A	MCP	list_issues	3 issues returned	ALLOWED	✅
A	MCP	list_pull_requests	3 PRs returned	ALLOWED	✅
A	MCP	get_file_contents (README.md)	content returned	ALLOWED	✅
A	MCP	list_commits	3 commits returned	ALLOWED	✅
B	MCP	add_issue_comment	`unknown tool` — absent from backend catalog	BLOCKED	⚠️
B	MCP	star_repository	`unknown tool` — absent from backend catalog	BLOCKED	⚠️
B	MCP	issue_write (create)	`unknown tool` — absent from backend catalog	BLOCKED	⚠️
B	MCP	create_branch	`unknown tool` — absent from backend catalog	BLOCKED	⚠️
C	CLI (`github`)	list_issues	data returned	ALLOWED	✅
C	CLI (`github`)	get_file_contents	data returned	ALLOWED	✅
D	CLI (`gh`)	reaction/star/issue/comment/file writes	`gh` unauthenticated (no GH_TOKEN)	BLOCKED	⚠️
E	CLI (`gh`)	GraphQL addReaction/addStar/createIssue	`gh` unauthenticated (no GH_TOKEN)	BLOCKED	⚠️

Overall: INCONCLUSIVE

⚠️ Gaps to note:

Part B: All write MCP tools (add_issue_comment, star_repository, issue_write, create_branch, create_or_update_file, create_pull_request) returned Error [-32602]: unknown tool — absent from the backend catalog because GITHUB_READ_ONLY=1 prevents the GitHub MCP server from registering write tools. This confirms the gh-aw framework defense-in-depth, but does not independently confirm mcpg's own DIFC/guard layer since write calls never reach a write-capable backend.
Parts D & E: gh CLI has no GH_TOKEN set in this environment. All gh api write attempts returned "set the GH_TOKEN environment variable" without reaching GitHub API. Cannot confirm token-scope boundary enforcement.

No writes succeeded. No data was created, modified, or leaked.

🔒 mcpg read-only stress (gVisor runtime) by Read-Only Stress: gVisor runtime

github-actions · 2026-08-19T15:27:29Z

🔒 mcpg Read-Only Stress — docker-sbx

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: docker-sbx (KVM-isolated microVM)

Part	Surface	Op	Result	Expected	Status
A	MCP	reads (issues/PRs/file/commits)	data returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	all 7 tools absent from catalog	BLOCKED	⚠️
C	CLI	reads (issues, file contents)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	401 Bad credentials	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	401 Bad credentials	BLOCKED	⚠️

Overall: INCONCLUSIVE

Gaps:

⚠️ Part B: All 7 write tools absent from MCP catalog. The GitHub MCP backend runs with GITHUB_READ_ONLY=1 (gh-aw framework guarantee), so write tools are never registered. This confirms the backend defense-in-depth but cannot independently confirm mcpg DIFC/guard enforcement since write calls never reach a write-capable backend. Tracked as methodology gap.
⚠️ Parts D/E: gh token invalid (Bad credentials). All REST/GraphQL write attempts returned 401 — unauthenticated rejections, not gateway enforcement. No write leaked, but token-scope boundary could not be validated for this run.

No writes succeeded. All reads returned data.

🔒 mcpg read-only stress (docker-sbx runtime) by Read-Only Stress: docker-sbx runtime

Initial plan

32b6438

Copilot AI assigned Copilot and lpcox Aug 19, 2026

Copilot started work on behalf of lpcox August 19, 2026 13:56 View session

Copilot AI linked an issue Aug 19, 2026 that may be closed by this pull request

[go-fan] Go Module Review: tetratelabs/wazero #11491

Closed

Harden and consolidate wazero guard runtime configuration

d1bda6d

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Review Go module tetratelabs/wazero~~ Consolidate wazero guard runtime/module config and disable DWARF debug info by default Aug 19, 2026

Copilot finished work on behalf of lpcox August 19, 2026 14:06

Copilot AI requested a review from lpcox August 19, 2026 14:06

lpcox marked this pull request as ready for review August 19, 2026 14:37

Copilot AI balanced review requested due to automatic review settings August 19, 2026 14:37

Copilot started reviewing on behalf of lpcox August 19, 2026 14:38 View session

Copilot AI reviewed Aug 19, 2026

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Potential fix for pull request finding

d001f7d

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Copilot started work on behalf of lpcox August 19, 2026 14:49 View session

Merge origin/main into copilot/go-fan-module-review

1b011ef

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot finished work on behalf of lpcox August 19, 2026 14:57

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Copilot started work on behalf of lpcox August 19, 2026 15:04 View session

Remove unused newTestInterpreterRuntime helper to fix lint failure

9e9449f

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Copilot finished work on behalf of lpcox August 19, 2026 15:12

lpcox merged commit f3b1ad1 into main Aug 19, 2026
38 checks passed

lpcox deleted the copilot/go-fan-module-review branch August 19, 2026 15:29

Copilot AI mentioned this pull request Aug 21, 2026

Bump default CLI/MCP versions: Claude Code 2.1.237, Codex 0.148.0, GitHub MCP Server v1.10.0 github/gh-aw#54521

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Consolidate wazero guard runtime/module config and disable DWARF debug info by default - #11505

Consolidate wazero guard runtime/module config and disable DWARF debug info by default#11505
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github-actions Bot commented Aug 19, 2026

🔒 mcpg Read-Only Stress — default

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🔒 mcpg Read-Only Stress — gVisor

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github-actions Bot commented Aug 19, 2026

🔒 mcpg Read-Only Stress — docker-sbx

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Copilot AI commented Aug 19, 2026 •

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Production (`internal/guard/wasm_lifecycle.go`)