fix(agent-core-v2): make MCP initial connect non-blocking during startup

[7Sageer]

Related Issue

No linked issue — the problem is explained below.

Problem

In the v2 engine (kap-server / agent-core-v2), session creation synchronously awaited the workspace MCP initial connect: materializeSession awaited ISessionMcpHandle.ready, which only resolves after every configured MCP server has connected or timed out (default 30s per server). The TUI awaits session creation before starting its UI event loop, so a slow or hung MCP server left users staring at a blank terminal on startup — create, resume, and fork were all affected. Agent creation paid the same wait a second time via await mcpReady in the agent lifecycle.

The v1 engine does not have this problem: its Session constructor kicks off MCP loading fire-and-forget and only the first turn waits for the initial load, so the UI comes up immediately and the MCP latency overlaps with the user's reading/typing time.

What changed

Adopt the v1 timing in v2 — startup no longer waits for MCP; the first LLM step does:

• SessionLifecycleService.materializeSession no longer awaits this.mcp.ready (nor the ephemeral overlay's ready). Workspace MCP connection still starts immediately in the background, and status keeps flowing through the existing mcp.server.status / tool.list.updated events, so clients can observe readiness.
• AgentLifecycleService no longer captures/awaits the session MCP handle's ready before creating an agent; the now-unused ISessionMcpHandle injection is dropped.
• AgentMcpService registers an onWillBeginStep hook that awaits waitForInitialLoad(ctx.signal) before each LLM request, so the first step still sees the complete MCP tool list. The cost is one-time — the promise is already resolved for subsequent steps — and the hook is interruptible via the turn signal. The existing per-server waitUntil gate on MCP tool calls stays as a fallback.

Tests: flipped the three blocking assertions (session create/resume, agent create) to assert immediate return, re-gated the resume-hiding test on main-agent creation, added coverage that the first step waits for the initial MCP load while the second runs straight through, and made the shared-manager workspace-resources test await the seeded readiness explicitly. Full agent-core-v2 suite (289 files / 4512 tests) green, tsc --noEmit clean.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

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Latest commit: de1cf8c

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@moonshot-ai/kimi-code	Patch

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