Port content mapper inspector extension into bundled extension

[Andrew Branch (andrewbranch)]

Fixes #64055

This was originally something I completely vibed as a separate extension, and then ported into here after team feedback was positive on bundling it. I have not yet looked closely at the client side implementation.

Screen.Recording.2026-09-04.at.1.41.23.PM.mov

[Copilot]

🟡 Changes recommended

Offset encoding and mapper-registration invalidation currently break core inspector behavior.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds a bundled VS Code inspector for content-mapper virtual files, mappings, and diagnostic directives, addressing #64055.

Changes:

• Adds LSP requests for mapped-file metadata.
• Adds virtual documents, mapping highlights, hovers, and directive views.
• Adds protocol and helper tests.

File summaries

File	Description
tsc/internal/lsp/server.go	Implements inspector requests.
tsc/internal/lsp/server_contentmapper_test.go	Tests new requests.
tsc/internal/lsp/lsproto/lsp_generated.go	Adds generated protocol types.
tsc/internal/lsp/lsproto/_generate/generate.mts	Defines protocol generation inputs.
packages/vscode-typescript/test/index.test.ts	Registers the new test.
packages/vscode-typescript/test/contentMapperVirtualFiles.test.ts	Tests output identities.
packages/vscode-typescript/src/session.ts	Exposes inspector requests.
packages/vscode-typescript/src/extension.ts	Registers the inspector provider.
packages/vscode-typescript/src/diagnosticDirectivesView.ts	Implements the directives tree.
packages/vscode-typescript/src/contentMapperVirtualFiles.ts	Defines client models and identities.
packages/vscode-typescript/src/contentMapperVirtualDocuments.ts	Implements virtual documents and mapping UI.
packages/vscode-typescript/src/client.ts	Sends inspector LSP requests.
packages/vscode-typescript/package.nls.json	Adds contribution labels.
packages/vscode-typescript/package.json	Contributes commands, menus, and view.
packages/vscode-typescript/l10n/bundle.l10n.json	Adds localized runtime strings.

Review details

Files not reviewed (1)

• tsc/internal/lsp/lsproto/lsp_generated.go: Generated file

• Files reviewed: 14/15 changed files
• Comments generated: 4
• Review effort level: Balanced

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[Copilot]

🟡 Changes recommended

Restart synchronization can leave inspector documents stale, and absent directive ranges are reported as real source locations.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

Files not reviewed (1)

• tsc/internal/lsp/lsproto/lsp_generated.go: Generated file

Suppressed comments (1)

packages/vscode-typescript/src/contentMapperVirtualDocuments.ts:123

• Refreshing mapped outputs on server initialization races the contribution synchronization that initialization also triggers. For extension-contributed inferred mappers, this request can return no outputs, causing refresh to delete the tracked entries; the later synchronization event only updates the context, so already-open inspector documents remain deleted or stale after a restart. Defer refreshing tracked sources until contributions have synchronized.

                for (const source of this.sourceToVirtualUris.keys()) {
                    this.refreshSource(vscode.Uri.parse(source));
                }

• Files reviewed: 14/15 changed files
• Comments generated: 2
• Review effort level: Balanced