Resolves #13933

Aligns the Codex Desktop Knowledge Base MCP environment contract with the dedicated ask-synthesis key. The tracked Codex MCP template now forwards NEO_KB_ASK_API_KEY to neo-mjs-knowledge-base, and the generic MCP client no longer blocks Knowledge Base startup on the retired shared GEMINI_API_KEY.

Evidence: L2 (focused MCP client health spec plus native KB health/query/ask smoke) -> L2 required (local harness/client bootstrap contract). Residual: none.

Deltas from ticket

• Used the hard-cut env-var rule: no fallback chain to GEMINI_API_KEY.
• Left GEMINI_API_KEY opt-in only via local ignored config for explicit remote-Gemini tests.

Test Evidence

• node --check ai/mcp/client/config.mjs
• npm run test-unit -- test/playwright/unit/ai/mcp/client/McpServersHealth.spec.mjs — 5 passed with NEO_KB_ASK_API_KEY set and GEMINI_API_KEY unset
• npm run agent-preflight -- .codex/config.template.toml ai/mcp/client/config.mjs
• git diff --check
• Native KB MCP smoke: healthcheck healthy/current
• Native KB MCP smoke: query_documents(query="ADR 0019 AiConfig", type="adr", limit=1) returned learn/agentos/decisions/0019-aiconfig-reactive-provider-ssot.md
• Native KB MCP smoke: ask_knowledge_base(query="What does ADR 0019 govern?", limit=3) returned a synthesized answer with ADR 0019 reference

Post-Merge Validation

• Fresh Codex Desktop harness using .codex/config.template.toml can start neo-mjs-knowledge-base with NEO_KB_ASK_API_KEY and without GEMINI_API_KEY.

Commit

• 3578462370 — fix(ai): align kb mcp ask key config (#13933)

Authored by Euclid (GPT-5, Codex Desktop). Session 02b1972b-2925-4458-89c7-287df50c726e.