#228 fix(gemini): MCP exclusion + BOM-free config write on Windows (#219)

[Anonymous]

Originally created by: kumaakh

Summary

Fixes [#219] — Gemini CLI members on Windows were failing to receive compose_permissions config because:

1. Set-Content -Encoding UTF8 writes a BOM, which JSON parsers reject.
2. Gemini CLI auto-loads the globally registered apra-fleet MCP server, causing tool-conflict noise and unexpected behaviour during prompted sessions.

Changes (T1–T5)

• T1 — Research: Verified --allowed-mcp-server-names flag behavior live on fleet-dev2 (Gemini member). Confirmed empty string "" disables all MCP servers.
• T2 — BOM-free deliverConfigFile (src/tools/compose-permissions.ts): Replaced Set-Content -Encoding UTF8 (adds BOM) with [System.IO.File]::WriteAllText(…, New-Object System.Text.UTF8Encoding($false)) on Windows. Unix path unchanged.
• T3 — MCP exclusion in GeminiProvider (src/providers/gemini.ts):
• buildPromptCommand now appends --allowed-mcp-server-names "" so the fleet MCP server is never loaded inside a Gemini session.
• composePermissionConfig switches from mcp.excluded (Claude-specific) to mcpServers: {} (per-project settings override) to suppress the globally registered server.
• T4 + T5 — Unit tests: New tests in tests/compose-permissions.test.ts (T4) and tests/providers.test.ts (T5) assert BOM-free output and --allowed-mcp-server-names presence respectively.

Test plan

• [x] All 1113 existing tests pass (npm test)
• [x] T4: deliverConfigFile — Windows BOM-free write suite passes (3 assertions)
• [x] T5: buildPromptCommand includes --allowed-mcp-server-names assertion passes
• [x] Live verification on fleet-dev2 (Gemini member) confirmed MCP suppression works with --allowed-mcp-server-names ""
• [x] Reviewer (fleet-rev) approved Phases 1–3 and Phase 4 unit tests
• [x] Sprint cleanup committed on both fleet-dev and fleet-rev

Related

Closes [#219]

[Anonymous]

Ticket changed by: kumaakh

• status: open --> closed