Add marketplace ref support for plugin marketplaces

[Aaron Powell (aaronpowell)]

Description

This updates plugin marketplace references to support explicit Git refs and switches the default github/awesome-copilot marketplace to github/awesome-copilot#marketplace.

It also wires the marketplace ref through the related code paths so that:

• marketplace references can include #ref
• GitHub marketplace fetches read definition files from the configured ref instead of always using main
• ref-specific marketplace caches and clone locations stay distinct
• workspace marketplace settings can carry a ref
• tests cover parsing, fetching, and repository handling for ref-aware marketplaces

Related Issue

github/awesome-copilot#1368

Testing

Not run in this checkout. Local validation was blocked because
ode_modules and compiled out artifacts are not present.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds support for specifying a Git ref (via #ref) in plugin marketplace references, and ensures both caching and fetching honor that ref.

Changes:

• Extend marketplace reference parsing to capture optional #ref for GitHub shorthand and git URIs, and incorporate it into canonical IDs / cache paths.
• Wire the parsed ref through cloning and HTTP fetching logic (e.g., raw.githubusercontent.com/.../{ref}/...).
• Add/adjust tests to validate parsing, caching uniqueness, and ref-aware fetching behavior.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/common/plugins/workspacePluginSettingsService.ts	Accept ref in extraKnownMarketplaces entries and append #ref when parsing.
src/vs/workbench/contrib/chat/common/plugins/marketplaceReference.ts	Parse/encode #ref, update canonical IDs and cache segments to be ref-specific.
src/vs/workbench/contrib/chat/common/plugins/pluginMarketplaceService.ts	Fetch GitHub marketplace definitions from the configured ref.
src/vs/workbench/contrib/chat/browser/agentPluginRepositoryService.ts	Pass parsed ref through to repository cloning.
src/vs/workbench/contrib/chat/browser/chat.shared.contribution.ts	Update configuration description/default to mention #ref.
src/vs/workbench/contrib/chat/test/common/plugins/workspacePluginSettingsService.test.ts	Add test for parsing ref from extraKnownMarketplaces.
src/vs/workbench/contrib/chat/test/common/plugins/pluginMarketplaceService.test.ts	Add tests for parsing #ref, uniqueness by ref, and ref-based fetching.
src/vs/workbench/contrib/chat/test/browser/plugins/agentPluginRepositoryService.test.ts	Add tests for ref-specific cache path and cloning with ref.

Copilot's findings

• Files reviewed: 8/8 changed files
• Comments generated: 4

[Connor Peet (connor4312)]

thanks! Looks like a CI failure tho

Error: [core-ci                  ] [05:28:45] src/vs/workbench/contrib/chat/common/plugins/pluginMarketplaceService.ts(909,10): error TS6133: 'encodeGitHubPathSegment' is declared but its value is never read.

[Aaron Powell (aaronpowell)]

Connor Peet (@connor4312) CI passing now