sessions: Skip local cache entries poisoned by downgrade

[roblourens]

Summary

Ignore local startup-cache records whose native ahp-session URI scheme was incorrectly persisted as their agent provider by an older VS Code version.

After a downgrade, these records create adapters routed to the unregistered agent-host-ahp-session frontend type. Upgrading does not fix an already-created adapter when the host subsequently advertises the correct provider.

Reject only the known poisoned combination before adapter construction, retain healthy cached records, and rebuild the skipped sessions from authoritative host metadata. Mark the cache dirty so normal saving removes the invalid records. The cache generation and backend session identities remain unchanged.

The rejection is local-provider-only; remote and cloud cache behavior is preserved. This does not make older versions support native session URIs or repair previously saved references to incorrectly routed open panes.

Validation

• npm run typecheck-client — passed after correcting the test storage variables to use the generic IStorageService contract.
• npm run build-fast -- --client-only — passed.
• npm run build-fast — passed, including the extension outputs needed for live validation.
• ./scripts/test.sh --run src/vs/sessions/contrib/providers/agentHost/test/browser/localAgentHostSessionsProvider.test.ts --run src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostSessionsProvider.test.ts --grep 'cache|cached|opaque advertised|mixed resources' — passed, 45 tests.
• npm run eslint -- src/vs/sessions/contrib/providers/agentHost/browser/baseAgentHostSessionsProvider.ts src/vs/sessions/contrib/providers/agentHost/browser/localAgentHostSessionsProvider.ts src/vs/sessions/contrib/providers/remoteAgentHost/browser/cloudSandboxSessionsProvider.ts src/vs/sessions/contrib/providers/agentHost/test/browser/localAgentHostSessionsProvider.test.ts — passed.
• git diff --check — passed.

Five new regressions cover selective filtering, removal of an entirely poisoned cache while the host is unavailable, and authoritative Copilot/Claude/Codex reconstruction with fresh-provider restart. The first four regressions were run before the implementation and failed.

Live validation

Passed in a real Code OSS 1.142.0 Dev Agents window on macOS, using isolated copies of two actual poisoned cache records, their host databases and Copilot SDK sessions, plus a healthy legacy-session control.

• First startup logged exactly two rejected cache entries.
• Both affected conversations opened with the correct agent-host-copilotcli frontend identity and rendered request/response history.
• The healthy legacy conversation also opened successfully.
• The saved cache retained the native backend URIs and corrected their provider to copilotcli.
• After a full application quit and restart using the same isolated profile, all three conversations opened and rendered again. No poisoned-cache rejection warnings appeared on restart.
• The original profile cache remained unchanged, and no prompts were submitted.

Live evidence was retained locally as screenshots, sampled video and Playwright traces. Previously saved malformed open-pane references were excluded from the fresh validation profile and remain outside this fix's scope. The CI follow-up changes only TypeScript annotations in the tests; production code and live-validation inputs remain unchanged.

(Written by Copilot)

[github-actions]

Screenshot Changes

Base: 1d25d5df Current: 5449b694

Changed (1)

sessions/chatCompositeBar/MixedStatuses/Light

Before	After

[Copilot]

Copilot review overview

🟢 Approval recommended

The narrowly scoped fix preserves healthy and remote caches and is covered by focused regression tests.

Review effort: Balanced
Findings: None

What changed in this PR

Filters downgrade-poisoned local session-cache entries so authoritative host metadata can rebuild them correctly.

Changes:

• Adds provider-specific cache rejection support.
• Rejects only local ahp-session/ahp-session records and marks the cache dirty.
• Adds five regression scenarios covering filtering, cleanup, and reconstruction.

File	Description
baseAgentHostSessionsProvider.ts	Supports rejecting cached metadata.
localAgentHostSessionsProvider.ts	Filters poisoned local records.
cloudSandboxSessionsProvider.ts	Handles the optional cache-adoption result.
localAgentHostSessionsProvider.test.ts	Tests filtering and authoritative reconstruction.

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