Accept nested extensions/<name>/extension.mjs in external-plugin canvas checks by tlmii · Pull Request #2403 · github/awesome-copilot

tlmii · 2026-07-22T22:57:25Z

Problem

The external-plugin canvas-structure check required the canvas extension entry point to be a flat file at <pluginRoot>/extensions/extension.mjs. But the endorsed convention (AGENTS.md → Canvas Extensions) nests each extension in its own subfolder: <pluginRoot>/extensions/<name>/extension.mjs. Plugins following the nested convention — which install and run fine (e.g. upgrade-agent in #2394, whose install smoke test passes) — were falsely reported as "missing required canvas extension entry point."

This repo's own discovery helpers (eng/generate-marketplace.mjs, eng/generate-website-data.mjs) already probe the nested path; only the two external-plugin checks disagreed.

Fix

Both checks now locate the canvas entry point by accepting either the flat extensions/extension.mjs or at least one immediate subfolder containing extension.mjs, kept behaviorally aligned:

Quality gate (eng/external-plugin-quality-gates.mjs, git-object based): new locateCanvasEntryPoint checks the flat blob first, then enumerates extensions/ children via git ls-tree and probes each <name>/extension.mjs.
Intake (eng/external-plugin-intake.mjs, Contents-API based): new locateCanvasEntryPointViaApi checks the flat path, then walks the extensions/ directory listing for a subdir with extension.mjs.

A canvas plugin whose extensions/ contains no extension.mjs anywhere (flat or nested) still fails. eng/external-plugin-validation.mjs is unchanged.

Adversarial review hardening

A multi-model review surfaced three issues, addressed here:

Truncated tree listing (gate): the directory enumeration now uses git ls-tree -z via spawnSync (NUL-delimited, untruncated) instead of the 12 KB-capped runCommand, so large extensions/ directories no longer drop the real entry.
Coupled flat check (intake): the flat-path check is decoupled from the directory listing succeeding; a transient API error on the listing or a nested lookup now yields an unverifiable warning ("a maintainer should re-run intake") rather than a false rejection, matching the gate's infra-error philosophy.
Non-array listing (intake): the listing must be a JSON array (Array.isArray) before it is treated as a directory; otherwise a "must be a directory" error is raised.

Tests

eng/external-plugin-quality-gates.test.mjs: nested-subfolder pass, no-entry-anywhere fail, and a nested entry listed past the legacy output cap.
eng/external-plugin-intake.test.mjs (new): nested accept, flat accept, no-entry reject, unverifiable-on-listing-error warning, and flat-still-accepted when the listing errors.

All 11 tests pass; the new nested tests fail on the pre-fix code. npm run build, npm run plugin:validate, and npm run skill:validate all pass with no generated-file drift.

Note: distinct from #2397 / #2399 (tag-ref infra_error), though both touch the quality-gates file. Branched from main; #2399 was still open at push time, so no rebase was needed — expect only a light conflict if it lands first.

_{Generated via Copilot (Claude Opus 4.8) on behalf of @tlmii}

…as checks The external-plugin canvas structure check (quality gate) and intake validation both hardcoded a flat extensions/extension.mjs entry point, falsely rejecting the documented nested extensions/<name>/extension.mjs layout that installs and runs fine. Scan the extensions/ directory for a nested subfolder containing extension.mjs while still accepting the flat form for backward compatibility. Applied to both runCanvasStructureGate (git-object lookups) and validateCanvasPluginMetadata (Contents API), keeping them behaviorally aligned. Added regression coverage for both paths. Fixes #2402 Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Address multi-model review findings on the nested canvas extension fix: - Quality gate: enumerate extensions/ via 'git ls-tree -z' with spawnSync (NUL-delimited, untruncated) so large directories no longer drop the real entry past the 12KB output cap. - Intake: decouple the flat extensions/extension.mjs check from the directory listing, require an array listing (Array.isArray) before treating it as a directory, and surface an unverifiable (warning) result instead of a false rejection when the listing or a nested lookup hits a transient API error. - Add regression tests: nested entry beyond the legacy output cap (gate) and unverifiable/flat-still-accepted paths when the listing errors (intake). Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Updates external-plugin canvas validation to support nested extension entry points.

Changes:

Supports flat and nested extension.mjs layouts.
Handles lookup failures as unverifiable.
Adds regression tests for both validation paths.

Show a summary per file

File	Description
`eng/external-plugin-quality-gates.mjs`	Adds untruncated nested entry-point discovery.
`eng/external-plugin-quality-gates.test.mjs`	Tests nested and large directory layouts.
`eng/external-plugin-intake.mjs`	Adds API-based nested entry-point discovery.
`eng/external-plugin-intake.test.mjs`	Tests intake acceptance and failure handling.

Review details

Files reviewed: 4/4 changed files
Comments generated: 2
Review effort level: Medium

…intake Address PR review: the Contents API caps directory listings at 1,000 entries and required one request per extension subfolder, so a nested entry beyond the cap could be falsely rejected (the same truncation class the git gate avoids) and large repos risked latency / rate-limit exhaustion. Replace the per-subfolder Contents API enumeration with one recursive 'git/trees/<locator>?recursive=1' fetch and inspect 'extensions/extension.mjs' and immediate 'extensions/<name>/extension.mjs' paths locally. A truncated tree without a located entry point is reported as unverifiable (warning) rather than rejected, and refs are normalized so 'refs/tags/<tag>' resolves as a tree-ish. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Review details

Files reviewed: 4/4 changed files
Comments generated: 2
Review effort level: Medium

tlmii · 2026-07-23T23:21:13Z

+    }
+
+    const nestedEntryPoint = toPosixPath(extensionsDir, entry.name, "extension.mjs");
+    const nestedCheck = checkPathExistsAtLocator(repoDir, locator, nestedEntryPoint, "blob");


Good catch. Fixed in 437f916: locateCanvasEntryPoint now enumerates the extensions/ subtree with a single recursive git ls-tree -r -t -z and classifies the flat/nested entry points in memory, instead of spawning a git cat-file per immediate subfolder. Process count is now constant regardless of how many directories an untrusted repo packs under extensions/ — the 160-folder regression test dropped from ~10s to ~1.3s as a result.

_{Generated via Copilot (Claude Opus 4.8) on behalf of @tlmii}

tlmii · 2026-07-23T23:21:14Z

-      `submission: plugins tagged with "canvas" must include "extensions/extension.mjs" at ${releaseLocatorDescription}`,
-    );
-  } else if (extensionEntryResponse.kind === "apiError") {
+  const releaseTreeResponse = await fetchGitHubTree(repo, normalizeTreeish(releaseLocator), token);


Agreed — a root recursive fetch made verifiability depend on total repo size, so a large unrelated monorepo could deterministically return truncated: true and permanently block a valid plugin. Fixed in 437f916: intake now walks to the plugin's extensions directory one level at a time (resolveDirectoryTreeSha, bounded by path depth) to resolve its tree SHA, then fetches only that subtree recursively. A truncated result is now only possible for an implausibly large extensions directory itself, not the rest of the repo.

_{Generated via Copilot (Claude Opus 4.8) on behalf of @tlmii}

Address reviewer feedback on unbounded scaling for untrusted/large repos: - Quality gate: replace the per-candidate-directory git cat-file spawns in locateCanvasEntryPoint with a single recursive git ls-tree over the extensions subtree, classifying flat/nested entry points in memory. Process count is now constant regardless of how many folders live under extensions/. - Intake: stop fetching the recursive git tree from the repo root (which a large unrelated monorepo can push past the Trees API truncation limit and never validate). Walk to the plugin's extensions directory one level at a time to resolve its tree SHA, then fetch only that subtree recursively, so verifiability depends on the plugin's own size, not the whole repository. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

Review details

Files reviewed: 4/4 changed files
Comments generated: 0 new
Review effort level: Medium

tlmii and others added 2 commits July 22, 2026 15:39

Copilot AI review requested due to automatic review settings July 22, 2026 22:57

tlmii requested a review from aaronpowell as a code owner July 22, 2026 22:57

Copilot started reviewing on behalf of tlmii July 22, 2026 22:57 View session

Copilot AI reviewed Jul 22, 2026

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Comment thread eng/external-plugin-intake.mjs Outdated

Copilot AI review requested due to automatic review settings July 23, 2026 02:57

Copilot started reviewing on behalf of tlmii July 23, 2026 02:58 View session

Copilot AI reviewed Jul 23, 2026

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Copilot AI review requested due to automatic review settings July 23, 2026 23:20

Copilot started reviewing on behalf of tlmii July 23, 2026 23:21 View session

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Accept nested extensions/<name>/extension.mjs in external-plugin canvas checks#2403

Accept nested extensions/<name>/extension.mjs in external-plugin canvas checks#2403
tlmii wants to merge 4 commits into
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tlmii-fix-external-plugin-nested-canvas-extens

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tlmii commented Jul 22, 2026

Problem

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