feat: surface CLI subagent/skill events in chat + /agent command

[PureWeen]

Summary

Improves Copilot CLI feature parity by making the CLI's built-in agent system visible to PolyPilot users.

What's new

1. Subagent activity shown in chat

When the Copilot CLI automatically invokes a specialized agent (e.g. code-review, security-review) in response to a prompt, PolyPilot now shows system messages in the chat thread:

• 🤖 Agent: **Code Review** — agent selected by CLI
• ▶️ Starting agent: **Code Review** — description — agent invocation began
• ✅ Agent completed: **Code Review** — success
• ❌ Agent failed: **Code Review**: error — failure with error detail

The active agent name/display name is also tracked on AgentSessionInfo and cleared on completion/deselect.

Previously these events fell through to LogUnhandledSessionEvent with no user-visible feedback.

2. SkillInvokedEvent shown in chat

When the CLI invokes a skill plugin, a ⚡ system message is shown: Skill: **skillName (plugin)**.

3. Active agent badge in session info panel

When a subagent is active, a 🤖 AgentName badge appears in the ExpandedSessionView info strip alongside the model selector.

4. /agent slash command

New /agent command with three modes:

• /agent — lists available agents from both local discovery (.github/agents/, .claude/agents/, .copilot/agents/) and the live SDK AgentApi.ListAsync()
• /agent <name> — selects an agent via AgentApi.SelectAsync(name)
• /agent deselect — deselects the current agent via AgentApi.DeselectAsync()

Added to autocomplete in index.html and updated /help output.

SdkEventMatrix updates

• SubagentSelectedEvent, SubagentDeselectedEvent, SubagentStartedEvent, SubagentCompletedEvent, SubagentFailedEvent: TimelineOnly → ChatVisible
• SkillInvokedEvent: TimelineOnly → ChatVisible

Tests

• SlashCommandAutocompleteTests updated to include /agent in the withArgs list
• All 2987 tests pass; MAUI Mac Catalyst build succeeds with 0 errors

[PureWeen]

Review: PR #445 — feat: surface CLI subagent/skill events in chat + /agent command

⚠️ Breaking change: /reflect command removed

The diff removes the /reflect case from the command switch and replaces it with /fleet. The HandleReflectCommand method is deleted from Dashboard.razor. The InsertReflectCommand shortcut button is also removed from ExpandedSessionView.razor.

This is a significant behavioral removal. /reflect was the user-facing entry point for reflection cycles. However:

• The underlying reflection cycle infrastructure (StopReflectionCycle, ReflectionCycle model, OrchestratorReflect mode) still exists and is referenced in both files
• The reflection pill UI (showing iteration progress, stop button) still renders in ExpandedSessionView.razor
• /reflect is removed from autocomplete in index.html and from the /help text

The user can no longer start a reflection cycle via /reflect, but the existing infrastructure for running them (e.g., via multi-agent orchestrator mode) remains. If this removal is intentional, the leftover ReflectionCycle UI and references should be cleaned up. If it was accidental, /reflect needs to be re-added.

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✅ Event handling — correct

The new subagent/skill event cases are well-structured:

• SubagentSelectedEvent: Sets ActiveAgentName/ActiveAgentDisplayName on AgentSessionInfo and adds a system message. Correct.
• SubagentDeselectedEvent: Clears both fields. Correct.
• SubagentStartedEvent: Adds a ▶️ message. The description is appended only when non-empty. Correct.
• SubagentCompletedEvent / SubagentFailedEvent: Clears ActiveAgentName only when the name matches (OrdinalIgnoreCase). This is a nice correctness guard against stale state from rapid sequential agent invocations.
• SkillInvokedEvent: Adds ⚡ message with plugin name. Correct.
• CommandsChangedEvent: Added as TimelineOnly — a reasonable default for an event that has no user-visible meaning yet.

All cases use Invoke(() => ...) for correct UI-thread marshaling. All use NotifyStateChangedCoalesced() consistently with surrounding code.

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✅ /agent command — correct

HandleAgentCommand in Dashboard.razor correctly handles three cases:

• Empty arg → list agents (SDK API + local discovery)
• deselect → calls DeselectAgentAsync
• Any other arg → calls SelectAgentAsync

The service methods (ListAgentsFromApiAsync, SelectAgentAsync, DeselectAgentAsync) all have proper null guards and exception handling (catch-and-log). ✅

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✅ /fleet command — correct but minimal

HandleFleetCommand calls StartFleetAsync which calls state.Session.Rpc.Fleet.StartAsync. The "fleet started" message fires before the API result is confirmed:

session.History.Add(ChatMessage.SystemMessage($"🚀 Starting fleet for: *{arg}*"));
var started = await CopilotService.StartFleetAsync(sessionName, arg);
    session.History.Add(ChatMessage.ErrorMessage("Failed to start fleet mode."));

This is a minor UX issue — "Starting fleet..." appears briefly even on failure. Low severity, but worth noting.

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✅ Active agent badge — correct

The badge in ExpandedSessionView.razor uses Session.ActiveAgentDisplayName ?? Session.ActiveAgentName with a null guard. CSS uses var(--type-footnote) — consistent with font-sizing conventions. ✅

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Minor: AgentSessionInfo.ActiveAgentName not persisted

ActiveAgentName/ActiveAgentDisplayName are not included in session persistence/bridge sync. After an app restart or remote-mode reconnect, the badge won't show. This is acceptable (the agent state is runtime-only and the SDK will re-emit events on reconnect), but worth documenting.

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Summary

Issue	Severity
/reflect removed — breaking change, or leftover UI needs cleanup	High — needs explicit decision
"Starting fleet" message before API confirms	Low
ActiveAgentName not persisted	Low/Info

All new event handling, API methods, and UI additions are correct. The /reflect removal is the only issue requiring a decision before merging.

[PureWeen]

Thanks for the thorough review @PureWeen!

On /reflect removal: This was intentional per the user's explicit request. The reflection pill UI (iteration counter, stop button) and all underlying infrastructure (ReflectionCycle, OrchestratorReflect, StopReflectionCycle) are intentionally retained — they still work when reflection is triggered via multi-agent orchestration. The removal only affects the user-facing /reflect slash command entry point. The leftover UI is not dead code — it activates when multi-agent orchestration starts a reflection cycle.

On fleet message before API confirms: Fixed in 00bff88 — the 🚀 message now only appears after StartFleetAsync returns true, error message on false.

On ActiveAgentName not persisted: Agreed this is acceptable — the SDK will re-emit subagent events on reconnect/resume. Not persisting is the right call to avoid stale badge state.