agentHost: adopt channel-based AHP wire model

[connor4312]

agentHost: adopt channel-based AHP wire model

Adopts the channel-based Agent Host Protocol revision from
microsoft/agent-host-protocol#127. Subscriptions, action delivery, and
protocol notifications now all route over named channels identified by a
top-level channel: URI field, replacing the pre-channels subscribe /
dispatch / notify model.

• Renames ROOT_STATE_URI from agenthost:/root to ahp-root:// and
  adds an isAhpRootChannel helper that tolerates both the canonical
  wire form and the workbench URI round-tripped form (ahp-root:).
• Threads a channel parameter through every action dispatch path:
  IAgentService.dispatchAction, IAgentConnection.dispatch,
  AgentHostStateManager.dispatchServerAction / dispatchClientAction,
  and AgentSubscriptionManager.dispatchOptimistic. Individual action
  payloads no longer carry session / terminal / changeset fields;
  the envelope carries the channel.
• Replaces the { method: 'notification', params: { notification } }
  wrapper with top-level JSON-RPC methods (root/sessionAdded,
  root/sessionRemoved, root/sessionSummaryChanged, auth/required).
  Each notification's params now carry their own channel: URI field.
• Renames the per-command identifying field to channel for the channel-
  scoped commands (createSession, disposeSession, createTerminal,
  disposeTerminal, fetchTurns, completions,
  invokeChangesetOperation). Connection-level commands hard-code the
  root channel string.
• Updates the subscribe result to { snapshot? } and the
  SubscribeParams / UnsubscribeParams field name from resource to
  channel.
• Drops the removed ProtocolNotification, NotificationType,
  NotificationMethodParams, and NotificationMap exports; provides a
  thin compat NotificationType constant keyed by method name for
  consumers that still discriminate notification variants.
• Adapts AgentSubscription routing to switch on envelope.channel
  rather than inspecting per-action URI fields (_isRelevantEnvelope
  replaces _isRelevantAction).
• Migrates all producers (agentService, agentSideEffects,
  agentConfigurationService, agentHostChangesetService,
  agentHostTerminalManager, agentHostStateManager,
  protocolServerHandler, Claude/Copilot agent sessions, terminal
  manager, etc.) and consumers (workbench session handler, terminal
  contribution, pty, customization harness, provider tests) to the new
  shapes.

(Commit message generated by Copilot)

[Copilot]

Pull request overview

This PR updates VS Code’s Agent Host integration to the channel-based Agent Host Protocol (AHP) wire model: routing subscriptions, action delivery, and protocol notifications through a top-level channel field and switching notifications to top-level JSON-RPC methods.

Changes:

• Introduces ahp-root:// as the root channel plus isAhpRootChannel to tolerate URI round-tripping.
• Threads channel through dispatch paths and removes per-action session/terminal/changeset routing fields in favor of envelope routing.
• Migrates protocol notification wiring from a notification wrapper to top-level methods like root/sessionAdded and updates tests/consumers accordingly.

Show a summary per file

File	Description
src/vs/workbench/services/agentHost/test/common/agentHostPermissionService.test.ts	Updates permission requests to carry channel.
src/vs/workbench/services/agentHost/browser/editorRemoteAgentHostServiceClient.ts	Updates dispatch API to require channel.
src/vs/workbench/contrib/terminal/test/browser/agentHostPty.test.ts	Updates terminal PTY tests for channel-scoped actions/envelopes.
src/vs/workbench/contrib/terminal/browser/agentHostPty.ts	Sends terminal actions via channel + action envelope.
src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostUntitledProvisionalSessionService.test.ts	Updates dispatch expectations to include channel.
src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostTerminalContribution.test.ts	Updates mock dispatches and assertions for channel-based dispatch.
src/vs/workbench/contrib/chat/test/browser/agentSessions/agentHostClientTools.test.ts	Updates session tool routing to use channels rather than action.session.
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/loggingAgentConnection.ts	Logs dispatches as { channel, action }.
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostUntitledProvisionalSessionService.ts	Dispatches session config changes with explicit channel.
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostTerminalContribution.ts	Dispatches root config changes against ROOT_STATE_URI.
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostSessionListController.ts	Switches to new notification types (root/session*).
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostSessionHandler.ts	Removes per-action session/terminal routing fields; uses channel routing.
src/vs/workbench/contrib/chat/browser/agentSessions/agentHost/agentHostChatInputPicker.ts	Dispatches config changes with channel-scoped dispatch.
src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostSessionsProvider.test.ts	Updates provider tests for channel-based notifications/actions.
src/vs/sessions/contrib/providers/remoteAgentHost/test/browser/remoteAgentHostCustomizationHarness.test.ts	Updates customization harness tests for channel-scoped dispatch.
src/vs/sessions/contrib/providers/remoteAgentHost/browser/remoteAgentHostCustomizationHarness.ts	Dispatches root customization config on ROOT_STATE_URI.
src/vs/sessions/contrib/providers/agentHost/test/browser/localAgentHostSessionsProvider.test.ts	Updates provider tests for channel-based notifications/actions.
src/vs/sessions/contrib/providers/agentHost/browser/baseAgentHostSessionsProvider.ts	Updates provider dispatch paths to supply channel and use root channel.
src/vs/platform/agentHost/test/node/reducers.test.ts	Adjusts reducer tests for removed per-action routing fields.
src/vs/platform/agentHost/test/node/protocol/turnExecution.integrationTest.ts	Updates subscribe params and snapshot optionality handling.
src/vs/platform/agentHost/test/node/protocol/testHelpers.ts	Updates handshake/session creation helpers to channel-based params.
src/vs/platform/agentHost/test/node/protocol/sessionLifecycle.integrationTest.ts	Updates notification expectations and subscribe shape usage.
src/vs/platform/agentHost/test/node/protocol/sessionFeatures.integrationTest.ts	Updates protocol feature tests to new subscribe + notifications model.
src/vs/platform/agentHost/test/node/protocol/sessionDiffs.integrationTest.ts	Updates session/changeset subscription params for channel-based subscribe.
src/vs/platform/agentHost/test/node/protocol/sessionConfig.integrationTest.ts	Updates session config tests for channel-based protocol (incomplete).
src/vs/platform/agentHost/test/node/protocol/realSdkTestHelpers.ts	Updates real-SDK test harness to new notification model (incomplete).
src/vs/platform/agentHost/test/node/protocol/multiClient.integrationTest.ts	Updates multi-client tests to channel-based protocol (incomplete).
src/vs/platform/agentHost/test/node/protocol/handshake.integrationTest.ts	Updates handshake tests for channel-based createSession + notifications.
src/vs/platform/agentHost/test/node/protocol/copilotRealSdk.integrationTest.ts	Updates assertions to use envelope channel instead of action.session.
src/vs/platform/agentHost/test/node/mockAgent.ts	Removes per-action session routing fields; relies on envelope channel.
src/vs/platform/agentHost/test/node/copilotSlashCommandCompletionProvider.test.ts	Updates completions params to use channel.
src/vs/platform/agentHost/test/node/copilotShellTools.test.ts	Updates terminal creation params (terminal → channel).
src/vs/platform/agentHost/test/node/copilotAgent.test.ts	Updates action envelopes for session routing removal.
src/vs/platform/agentHost/test/node/claudeMapSessionEvents.test.ts	Updates session event mapping tests to use envelope channel.
src/vs/platform/agentHost/test/node/claudeAgent.test.ts	Updates test assertions for channel-based session identification.
src/vs/platform/agentHost/test/node/agentService.test.ts	Updates dispatch/state-manager calls to channel-based API.
src/vs/platform/agentHost/test/node/agentHostTerminalManager.test.ts	Updates terminal manager tests for channel-based terminal identity.
src/vs/platform/agentHost/test/node/agentHostSkillCompletionProvider.test.ts	Updates completion params to use channel.
src/vs/platform/agentHost/test/node/agentHostFileCompletionProvider.test.ts	Updates file completion lookup to use params.channel.
src/vs/platform/agentHost/test/node/agentHostChangesetService.test.ts	Updates emitted envelopes assertions to check envelope.channel.
src/vs/platform/agentHost/test/electron-browser/remoteAgentHostProtocolClient.test.ts	Updates protocol-client tests for channel-based requests/errors.
src/vs/platform/agentHost/test/electron-browser/localAhpJsonlLogging.test.ts	Updates logging wrapper tests for channel-aware dispatchAction.
src/vs/platform/agentHost/test/common/agentSubscription.test.ts	Updates subscription routing to channel-based envelopes.
src/vs/platform/agentHost/node/sessionPermissions.ts	Updates tool-ready action creation (session routing removed).
src/vs/platform/agentHost/node/protocolServerHandler.ts	Updates server routing to channel-based subscribe/dispatch/notifications.
src/vs/platform/agentHost/node/copilot/copilotSlashCommandCompletionProvider.ts	Uses params.channel for copilot session gating.
src/vs/platform/agentHost/node/copilot/copilotShellTools.ts	Uses channel-based createTerminal params.
src/vs/platform/agentHost/node/copilot/copilotAgentSession.ts	Removes redundant session field from emitted actions.
src/vs/platform/agentHost/node/claude/claudeSubagentSignals.ts	Removes per-action session routing fields.
src/vs/platform/agentHost/node/claude/claudeSdkPipeline.ts	Removes per-action session routing fields.
src/vs/platform/agentHost/node/claude/claudeMapSessionEvents.ts	Removes per-action session routing fields.
src/vs/platform/agentHost/node/claude/claudeAgentSession.ts	Removes per-action session routing fields.
src/vs/platform/agentHost/node/agentService.ts	Changes dispatcher to accept channel + action and route attachments by channel.
src/vs/platform/agentHost/node/agentHostTerminalManager.ts	Routes terminal actions via envelope channel; root terminal list via root channel.
src/vs/platform/agentHost/node/agentHostStateManager.ts	Adds channel-aware dispatch and top-level notification methods.
src/vs/platform/agentHost/node/agentHostSkillCompletionProvider.ts	Uses params.channel when resolving agent candidates.
src/vs/platform/agentHost/node/agentHostFileCompletionProvider.ts	Uses params.channel for working directory lookup.
src/vs/platform/agentHost/node/agentHostChangesetService.ts	Emits changeset actions on changeset channel rather than in-action field.
src/vs/platform/agentHost/node/agentConfigurationService.ts	Dispatches root and session config updates on correct channel.
src/vs/platform/agentHost/electron-browser/localAgentHostService.ts	Updates local dispatcher and optimistic dispatch to require channel.
src/vs/platform/agentHost/common/state/sessionState.ts	Defines ahp-root:// and isAhpRootChannel.
src/vs/platform/agentHost/common/state/sessionProtocol.ts	Drops removed notification exports from sessionProtocol surface.
src/vs/platform/agentHost/common/state/sessionActions.ts	Reworks notification typing + compat NotificationType constants.
src/vs/platform/agentHost/common/state/protocol/version/registry.ts	Converts notification versioning to method-name based mapping.
src/vs/platform/agentHost/common/state/protocol/state.ts	Updates docs for URI/snapshot wording to channel-based model.
src/vs/platform/agentHost/common/state/protocol/notifications.ts	Defines top-level notification params (root/session*, auth/required) with channel.
src/vs/platform/agentHost/common/state/protocol/messages.ts	Updates notification maps and typed notification union for new methods.
src/vs/platform/agentHost/common/state/protocol/.ahp-version	Bumps synced protocol revision.
src/vs/platform/agentHost/common/state/agentSubscription.ts	Updates subscription routing to _isRelevantEnvelope and channel-based optimistic dispatch.
src/vs/platform/agentHost/common/agentService.ts	Updates IAgentService/IAgentConnection dispatch signatures to include channel.
src/vs/platform/agentHost/common/agentHostFileSystemProvider.ts	Adds channel: ROOT_STATE_URI to filesystem RPCs.
src/vs/platform/agentHost/browser/nullAgentHostService.ts	Updates null service dispatch signature to accept channel.

Copilot's findings

Comments suppressed due to low confidence (6)

src/vs/platform/agentHost/test/node/protocol/sessionConfig.integrationTest.ts:232

• This subscribe call is still using { resource: sessionUri }. The channel-based protocol expects { channel: sessionUri }, and SubscribeResult.snapshot is now optional so callers should handle snapshot.snapshot possibly being undefined.
  src/vs/platform/agentHost/test/node/protocol/sessionConfig.integrationTest.ts:194
• The persistence test still uses the pre-channels protocol shapes: subscribe is called with { resource: sessionUri } instead of { channel: sessionUri }. Additionally, the subsequent dispatchAction notification should now include a top-level channel and the action payload should not carry session (the channel is the envelope).
  src/vs/platform/agentHost/test/node/protocol/realSdkTestHelpers.ts:702
• This test still uses old protocol field names: subscribe is called with { resource: sessionUri } (should be { channel: sessionUri }). Also the preceding createSession call uses { session: ... } which should be { channel: ... } under the channel-based wire model.
  src/vs/platform/agentHost/test/node/protocol/realSdkTestHelpers.ts:522
• The real-SDK tests still call subscribe with { resource: ROOT_STATE_URI }. The updated protocol expects { channel: ROOT_STATE_URI } (and InitializeParams/other commands also now carry a channel: 'ahp-root://').
  src/vs/platform/agentHost/test/node/protocol/realSdkTestHelpers.ts:664
• This resubscribe still uses { resource: sessionUri }. With the channel-based protocol it should be { channel: sessionUri } (and callers should handle snapshot being optional on the result).
  src/vs/platform/agentHost/test/node/protocol/realSdkTestHelpers.ts:809
• Terminal subscriptions here still call subscribe with { resource: terminalUri }. The channel-based protocol expects { channel: terminalUri } (same for the subsequent subscribe call later in this test).

• Files reviewed: 80/80 changed files
• Comments generated: 6