Fix WSL resource links in Agent Host chat responses

[Dileep Yavanmandha (dileepyavan)]

Problem

File links and images in Agent Host chat responses can resolve against the local filesystem instead of the WSL filesystem when a locally identified session is backed by a WSL Agent Host connection.

The response URI resolver used the session handler's connectionAuthority to rewrite resource targets. That authority can remain local even though the active connection's resource URI mapper points to WSL. In that case an absolute Linux path or file: URI stays a local file URI rather than being routed through the owning Agent Host connection.

Reproduction scenario

1. Use an Agent Host chat session backed by a WSL connection while the session handler has a local authority.
2. Have the agent return a Markdown file link such as [file](/home/user/project/src/file.ts:42:7) or an image path in the WSL filesystem.
3. Open the file link or render the image.

Expected: Resolve through the WSL Agent Host connection, retaining the file path and line/column selection.

Actual before this fix: The target is interpreted as a local filesystem resource, so the intended WSL resource may not open or render.

Fix

• Pass the active connection's resourceUris mapper from AgentHostSessionHandler.resolveChatResponseUri into rewriteAgentHostLinkTarget.
• Map parsed targets with resourceUris.fromAgentHost rather than constructing their destination from the session authority alone.
• Keep an authority-based default mapper for existing callers.
• Add regression coverage for WSL file links with line/column selections, file: URIs, encoded image paths, and preservation of local, external, and already mapped links.

Validation

• 5 focused tests passed: the response resource links suite in agentHostChatContribution.test.ts and the rewriteAgentHostLinkTarget suite in stateToProgressAdapter.test.ts.
• No editor diagnostics in the three changed files.
• git diff origin/main...HEAD --check passed.

./scripts/test.sh \
  --run src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostChatContribution.test.ts \
  --run src/vs/workbench/contrib/chat/test/browser/agentSessions/stateToProgressAdapter.test.ts \
  --grep 'response resource links|rewriteAgentHostLinkTarget'

The WSL scenario is covered by unit regression tests; no end-to-end WSL UI validation was performed for this PR.

[Copilot]

Copilot review overview

Review tier: Balanced
Findings: 1

New issues introduced by this change (1)

Severity	Finding
	src/​vs/​workbench/​contrib/​chat/​browser/​agentSessions/​agentHost/​stateToProgressAdapter.ts — The local Agent Host uses identityAgentHostResourceUriMapper, so this now returns internal…

What changed in this PR

Routes Agent Host response links through the active connection’s resource URI mapper, fixing WSL-backed resources.

Changes:

• Use the connection mapper when rewriting links and images.
• Add WSL and link-preservation regression tests.

File	Description
agentHostSessionHandler.ts	Passes the active resource mapper.
stateToProgressAdapter.ts	Maps parsed response targets.
agentHostChatContribution.test.ts	Tests WSL links, images, and preserved targets.

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[github-actions]

Base: 9a754577 Current: f416a9de

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