Code mode: saved code tools (McpTool endpointMapping.method = 'code') #1363

Summary

Saved code tools: a tool whose endpointMapping.method = 'code' runs a stored program through the code-runner instead of calling one upstream endpoint. Depends on #1361 and the schema issue.

Scope

• Execution: a code branch in DynamicMcpTools.executeTool / executeWithEngine (dynamic-mcp-tools.ts, next to the static branch) that calls CodeExecutorService with a bridge scoped to the tool's uses connectors and the caller's role. Fields on endpointMapping: code, uses: [{connectorId, tools}], runAs: 'invoker' | 'definer' (definer = admin-only, stored-procedure semantics), allowWrites.
• Read/write: a code tool's own annotation derives from allowWrites; writes are only allowed in an admin-approved code tool, never inline.
• Tool editor: add code to METHODS_BY_TYPE and an editor panel (code + uses + runAs + allowWrites). Reuse assertCanWriteConnector (VIEWER blocked; owner/ADMIN only) and the secret guard.
• Offered only on servers whose connectors cover all uses. ToolRoleAccess, isEnabled, audit toolId, export/import work unchanged because it is an McpTool.
• Agent proposal: code_propose_tool → pending KgSkillSuggestion kind code → ADMIN approval.

Governance

Respect McpServerConfig.codeMode; policy never read from tool args; shared-endpoint exclusions reused; assertEnterprise for definer/writes where the plan gate requires it (see the gating issue).