v1.5 — Cursor MCP integration rework

Why a dedicated track

v1.4 added "type": "stdio" to generated .mcp.json and .cursor/mcp.json, matching Cursor docs for stdio MCP. That does not resolve the observed behaviour: TAUSIK tools still do not reach the Composer / workspace mcps/ mirror path that lists MCP servers for the agent tool surface.

The bootstrap or Python server being broken hypothesis is not supported here: venv, mcp import, .cursor/scripts/, and a manual server.py launch do not show an immediate crash.

Findings (2026-05-08)

Mcp FileSystem Writer.log (primary)

On each window reload:

1. cursor_mcp_lease_server_status lists four servers (including project-0-claude-tausik-project).
2. cursor_mcp_lease_snapshot_store then lists only cursor-ide-browser.
3. fetchAndWrite: lease returned 26 tools across 1 clients — only the browser client is written.

So project stdio servers are visible in lease status but not included in the FS-writer snapshot that feeds the agent tool filesystem mirror.

workbench.mcp.oauth.log

Project entries show disconnected; browser shows connected. This channel is OAuth-oriented; treat disconnected for raw stdio as non-authoritative for “process failed”.

Historical contrast (2026-05-06)

Global user-* servers, when healthy, did appear in cursor_mcp_lease_snapshot_store with large tool counts. So stdio can flow through snapshot — project-prefixed servers behave differently in observed logs.

v1.5 goals (minimum)

1. Maintain a host contract matrix: Cursor docs promise vs actual FS mirror behaviour per release.
2. Explore mitigations: HTTP/SSE bridge, Cursor Extension MCP registration, out-of-IDE MCP handshake diagnostic script, upstream Cursor issue with repro + FileSystem Writer excerpts (no secrets).
3. User docs: Composer vs CLI without mandating global ~/.cursor/mcp.json where project policy forbids it.

Regression guards

• .tausik/tausik CLI remains the supported full workflow if MCP is unavailable.
• No bootstrap test regressions; no secrets committed.

RU mirror: docs/ru/research/tausik-1.5-mcp-cursor-rework-2026-05-08.md.