[pull] main from microsoft:main - #1594

* Avoid blocking agent host startup on proxy resolution

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Defer proxy restart during credential updates

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Refresh proxy on every Copilot client start

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: resolve archived divergent Copilot backings

Fixes #331030\n\n(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: persist resolved resume roots

Keep the resolved primary directory aligned with the ordered working-directory metadata when restoring divergent Copilot backings.\n\n(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Consume the existing buffer mark iterator instead of repeatedly creating a new iterator that returns the first marker. Add a regression test for marker navigation without command detection.\n\nFixes #331034\n\n(Written by Copilot)\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add Agent Host startup telemetry

Track connection, authentication, and initial session-list startup phases, including retries, terminal failures, and timeouts. (Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Attribute post-connection startup failures to the session-list stage

A terminal connection close after AHP connected was reported as a protocolConnection failure, matching neither the timeout path nor reality. (Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Keep the synchronously created input model alive until its resolver reference takes ownership, and dispose late references when the widget has already closed. Add a regression test for immediate disposal during reference acquisition.\n\n(Written by Copilot)\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: Preserve detached shells during idle eviction

Let SDK session.idle complete the AHP turn normally, but defer non-destructive provider release while Copilot reports a running detached shell. Keep cached state until release succeeds, retry deferred releases, and preserve reconnect ordering while release is in flight.

Add focused unit coverage plus a real bundled-SDK mock-LLM integration test that verifies detached work survives beyond the release grace.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: Normalize idle release coordination

Key idle-release timers by the owning root session so chat and subagent subscriptions cancel and re-arm the same retry. Preserve the original in-flight provider release promise when overlapping timers fire.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: Adapt idle release to chat lifecycle

Split idle release into a provider preflight and chat teardown so detached shells can veto eviction while successful releases preserve state-first reconstruction. Normalize release coordination across all chats and update restart coverage to unsubscribe every open chat.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: Remove no-op Claude release change

Restore the original combined release guard after the chat release contract returned to void semantics.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* sessions: Cache Agent Host session metadata

Persist pull request metadata and aggregate change counts so cached Agent Host sessions render complete list rows before the first live refresh.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* sessions: Clear cached change summaries

Handle explicit change-summary clears so stale aggregate counts are not persisted and restored.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* agentHost: Preserve summary clears over the wire

Represent aggregate change-summary clears with an additive protocol marker and cover both transport serialization and metadata-only cache persistence.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* sessions: Keep cache change protocol-neutral

Remove the locally invented summary-clear wire marker while retaining isolated coverage for change-stat and metadata-only cache persistence.

(Written by Copilot)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>