agentHost: multi-root turn changesets and session diff summary

[Don Jayamanne (DonJayamanne)]

No description provided.

[Copilot]

Pull request overview

Adds multi-root Agent Host diff aggregation, repository-aware blob resolution, and all-folder session summaries.

Changes:

• Aggregates turn diffs across Git and non-Git workspace roots.
• Adds multi-folder summary and operation/UI filtering behavior.
• Expands unit coverage for aggregation, filtering, and blob URIs.

Show a summary per file

File	Description
src/vs/sessions/contrib/providers/agentHost/test/browser/agentHostSessionChangesets.test.ts	Tests primary-root filtering.
src/vs/sessions/contrib/providers/agentHost/browser/baseAgentHostSessionsProvider.ts	Passes workspace observables to changesets.
src/vs/sessions/contrib/providers/agentHost/browser/agentHostSessionChangesets.ts	Filters displayed turn changes.
src/vs/platform/agentHost/test/node/sessionDiffAggregator.test.ts	Tests root-filtered aggregation.
src/vs/platform/agentHost/test/node/gitDiffContent.test.ts	Updates blob URI expectations.
src/vs/platform/agentHost/test/node/agentSideEffects.test.ts	Updates changeset fake.
src/vs/platform/agentHost/test/node/agentHostTurnTelemetry.test.ts	Updates telemetry fake.
src/vs/platform/agentHost/test/node/agentHostToolCallTelemetry.test.ts	Updates telemetry fake.
src/vs/platform/agentHost/test/node/agentHostMultiRootDiff.test.ts	Tests multi-root orchestration.
src/vs/platform/agentHost/test/node/agentHostCommitOperationHandler.test.ts	Updates changeset test service.
src/vs/platform/agentHost/test/node/agentHostChangesetOperationService.test.ts	Tests operation suppression.
src/vs/platform/agentHost/test/node/agentHostChangesetCoordinator.test.ts	Tracks summary refreshes.
src/vs/platform/agentHost/test/common/sessionTestHelpers.ts	Updates no-op service helper.
src/vs/platform/agentHost/test/common/agentHostWorkingDirectories.test.ts	Tests root selection utilities.
src/vs/platform/agentHost/node/sessionDiffAggregator.ts	Adds root-based edit filtering.
src/vs/platform/agentHost/node/gitDiffContent.ts	Exposes blob absolute paths.
src/vs/platform/agentHost/node/agentService.ts	Resolves owning blob repository.
src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts	Implements multi-root aggregation.
src/vs/platform/agentHost/node/agentHostChangesetService.ts	Computes turn diffs and summaries.
src/vs/platform/agentHost/node/agentHostChangesetOperationService.ts	Suppresses aggregate operations.
src/vs/platform/agentHost/node/agentHostChangesetCoordinator.ts	Starts summary refreshes.
src/vs/platform/agentHost/common/agentService.ts	Documents summary semantics.
src/vs/platform/agentHost/common/agentHostWorkingDirectories.ts	Adds repository-root selection.
src/vs/platform/agentHost/common/agentHostChangesetService.ts	Extends the changeset service API.

Review details

Suppressed comments (1)

src/vs/platform/agentHost/node/agentHostChangesetOperationService.ts:101

• This does not mirror the changeset service's gate: that service uses getEffectiveWorkingDirectories, which inherits a parent's roots for subagents, while this reads only the child session's own state. A subagent without its own directories under a multi-root parent therefore gets an aggregated turn changeset but still advertises primary-repository operations. Use IAgentConfigurationService.getEffectiveWorkingDirectories here too.

	private _isMultiFolderCopilot(sessionKey: string): boolean {
		if (AgentSession.provider(sessionKey) !== 'copilotcli') {
			return false;
		}
		const dirs = this._stateManager.getSessionState(sessionKey)?.workingDirectories;
		return !!dirs && dirs.length > 1;

• Files reviewed: 24/24 changed files
• Comments generated: 8
• Review effort level: Balanced

[Copilot]

Review details

Suppressed comments (7)

src/vs/platform/agentHost/node/agentHostChangesetOperationService.ts:78

• Compare-turns changesets are still computed only from workingDirectories[0] in AgentHostChangesetService.computeCompareTurnsChangeset (lines 479-521), so they do not aggregate repositories. This condition removes valid primary-repository operations based on a false assumption. Either aggregate compare-turns across roots too, or restrict suppression to ChangesetKind.Turn.

		if ((parsed.kind === ChangesetKind.Turn || parsed.kind === ChangesetKind.Compare) && this._isMultiFolderCopilot(sessionKey)) {

src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts:131

• Pushing into gitResults from parallel callbacks makes result order depend on which repository finishes first. That contradicts the documented effective-directory ordering and also makes the winner for duplicate IDs nondeterministic. Return each target's result from Promise.all and flatten in gitTargets order instead.

			gitResults.push(...diff);

src/vs/platform/agentHost/node/sessionDiffAggregator.ts:147

• options is silently ignored whenever incremental is supplied: only the full-mode branch forwards it, while incremental turn edits, full history, and carried previousDiffs remain unfiltered. Either apply the filter throughout incremental mode or make the API reject/disallow this argument combination.

	options?: IDiffFilterOptions,

src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts:162

• This deduplicates URI identities by raw string, so casing variants of the same file remain separate on case-insensitive platforms. Use extUriBiasedIgnorePathCase.getComparisonKey(URI.parse(resource)), consistent with src/vs/base/common/resources.ts:340-344 and the repository URI-key convention.

		const id = diff.after?.uri ?? diff.before?.uri;
		if (!id) {
			continue;
		}
		byId.set(id, diff);

src/vs/platform/agentHost/common/agentHostWorkingDirectories.ts:33

• Reconstructing a file URI from only absolutePath loses UNC authority. A root such as file://server/share/repo carries server in authority, while buildGitBlobUri stores only the file URI's .path; this creates file:///share/repo/..., which can never match the trusted root and makes secondary UNC diffs fail with NotFound. Carry the complete file URI (or its authority) through the git-blob URI.

export function selectRepositoryRootForBlobPath(absolutePath: string, repositoryRoots: readonly URI[]): URI | undefined {
	const fileUri = URI.from({ scheme: Schemas.file, path: absolutePath });
	return findDeepestContainingWorkingDirectory(fileUri, repositoryRoots);

src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts:85

• The safety cap is applied only after this Promise.all has launched a repository-root probe for every directory. Since each distinct probe can run git rev-parse, a pathological workspace still creates unbounded concurrent processes before the 20-target cap takes effect. Resolve with bounded concurrency and stop once enough unique targets have been collected.

	const resolved = await Promise.all(workingDirectories.map(async dir => {
		try {
			return { dir, repoRoot: await ctx.getRepositoryRoot(dir) };

src/vs/platform/agentHost/node/agentHostChangesetService.ts:816

• This JSDoc enumerates implementation branches and internal scheduling details across 21 lines. Sessions guidance limits JSDoc to 1–2 short sentences; condense it to the method's purpose and leave the implementation details in the named helpers.

	/**
	 * Computes the branch changeset AND the all-folder session-list summary for a
	 * multi-root Copilot session in a single pass (Problem 2), folded together so
	 * the primary repository is diffed exactly once and every folder is diffed in
	 * parallel.

• Files reviewed: 15/15 changed files
• Comments generated: 1
• Review effort level: Balanced

[Copilot]

Review details

Suppressed comments (4)

src/vs/platform/agentHost/common/agentHostWorkingDirectories.ts:33

• Reconstructing the file URI from path alone always uses an empty authority. For a UNC repository, URI.file('\\\\server\\share\\repo') has authority server, while this reconstructed URI does not, so isEqualOrParent never finds the owning root and multi-root git-blob reads return NotFound. Preserve the original file URI authority (or the complete file URI) in the git-blob payload and reconstruct it here.
  src/vs/platform/agentHost/node/agentHostChangesetService.ts:832
• Secondary repositories are diffed without a baseBranch. computeSessionFileDiffs explicitly falls back to HEAD in that case, so the all-folder summary omits committed-on-branch changes from every non-primary repository. Resolve each secondary repository's default branch and pass it into the diff computation.

	}

	/**

src/vs/platform/agentHost/node/sessionDiffAggregator.ts:147

• options is only forwarded in full mode; when incremental is also supplied, includeUnder is silently ignored and both newly loaded edits and carried previousDiffs can contain files outside the requested roots. Either support filtering throughout the incremental path or reject/document this parameter combination so this exported API cannot return an unfiltered result.

	incremental?: IIncrementalDiffOptions,
	options?: IDiffFilterOptions,

src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts:83

• The safety cap is applied only after this mapping has started a repository-root probe for every working directory. A pathological workspace can therefore still launch an unbounded number of concurrent Git processes before being truncated to 20 targets, defeating the cap's resource-protection purpose. Bound/concurrency-limit root resolution or stop once enough unique targets have been identified.

		try {

• Files reviewed: 17/17 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[Copilot]

Review details

Suppressed comments (6)

src/vs/platform/agentHost/node/agentHostChangesetService.ts:811

• This fallback reads only the parent session database. Peer chats record file edits in separate databases (see _openPeerChatSources in this file), so any non-Git or failed-Git root omits peer-chat edits from the new all-folder summary. Include all peer-chat sources in the filtered union and dispose their database refs after the aggregate finishes.

			computeFallbackDiff: roots => computeUnionedDiffs([{ sessionUri: session, db }], this._diffComputeService, { includeUnder: roots }),

src/vs/platform/agentHost/node/agentHostChangesetCoordinator.ts:138

• A real root-set mutation never invalidates the changeset data here: 2→3 returns immediately, while 1→2 only refreshes operation metadata below. Because this is the only working-directory mutation hook, subscribed Branch/Session/Turn changesets and summary.changes remain computed from the old roots until an unrelated edit or Git refresh. Recompute subscribed changesets for every non-idempotent root change, and keep the boundary check only for operation suppression.

		const wasMultiRoot = (previousWorkingDirectories?.length ?? 0) > 1;
		const isMultiRoot = (currentWorkingDirectories?.length ?? 0) > 1;
		if (wasMultiRoot === isMultiRoot) {
			return;

src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts:101

• Concurrent callbacks append to gitResults in completion order, and the final Map preserves that order. Repository timing can therefore reorder the same changeset between refreshes; the client equality check is order-sensitive, so this also causes unnecessary updates and visible file-list jumps. Return each result from Promise.all and flatten them in gitTargets order.

			successfulTargetCount++;
			gitResults.push(...diff);
		} catch (err) {
			ctx.logService.error(`[MultiRootDiff] Git diff failed for ${repoRoot.toString()} in ${ctx.session}: ${errText(err)}; falling back to edit-tracker.`);
			fallbackRoots.push(repoRoot);

src/vs/platform/agentHost/common/agentHostWorkingDirectories.ts:26

• absolutePath came from URI.path, which does not carry a file URI's authority. Reconstructing an authority-less URI here cannot match UNC roots such as file://server/share/repo, so multi-root git-blob content resolution returns NotFound for those repositories. Carry the complete absolute file URI (including authority) in the blob metadata instead of only its path.

export function selectRepositoryRootForBlobPath(absolutePath: string, repositoryRoots: readonly URI[]): URI | undefined {
	const fileUri = URI.from({ scheme: Schemas.file, path: absolutePath });
	return findDeepestContainingWorkingDirectory(fileUri, repositoryRoots);

src/vs/sessions/contrib/providers/agentHost/browser/agentHostSessionChangesets.ts:37

• For a rename, change.uri is the after path, so moving a file from the primary checkout to another root is dropped even though the primary checkout lost that file. This also conflicts with the backend filter, which deliberately retains renames when either the current or original path is under a selected root. Include the before-side path when deciding primary-root membership.

	return changes.filter(change => {
		const resource = isIChatSessionFileChange2(change) ? change.uri : change.modifiedUri;
		return extUriBiasedIgnorePathCase.isEqualOrParent(resource, primaryRoot);

src/vs/platform/agentHost/node/agentHostMultiRootDiff.ts:55

• The target cap is applied only after every working directory has concurrently run getRepositoryRoot. Since working-directory actions have no count limit and this lookup invokes Git, a large root set can still launch an unbounded number of subprocesses despite MAX_MULTI_ROOT_DIFF_TARGETS. Bound the resolution concurrency and stop once the retained target budget is satisfied.

	const resolved = await Promise.all(workingDirectories.map(async dir => {
		try {
			return { dir, repoRoot: await ctx.getRepositoryRoot(dir) };

• Files reviewed: 22/22 changed files
• Comments generated: 0 new
• Review effort level: Balanced