fix(spawn): sub-agents inherit parent MCP server refs#482
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A spawned sub-agent silently lost access to every MCP server the parent was granted: build_sub_agent_crd_with_labels emitted spec.governance but never copied governance.mcpServerRefs, so e.g. a Playwright-MCP parent spawned children with no browser tools. The spawn path already fetches the parent CR (for label inheritance); it now also extracts the parent's effective governance.mcpServerRefs (parent_mcp_server_refs, honoring the deprecated singular mcpServerRef shim like GovernanceConfig::effective_mcp_server_refs) and overlays them onto the child's spec.governance. Refs are by-name into the child CR's namespace — the parent's namespace, where the McpServer CRs and <parent>-inference/-toolpolicy already live — so they resolve verbatim and the controller mirrors the JWKS/signing material + derives the MCP egress rule for the child exactly as it does for the parent. Tests live in the sibling mcp_inherit_test.rs submodule to keep spawn/mod.rs lean; phase0 LOC cap bumped 1400->1450 for the new logic. Also documents the inheritance in docs/mcp.md and de-pins the getting-started install to @latest so docs don't drift each release. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Dependency Review✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.Scanned FilesNone |
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Problem
A spawned sub-agent silently loses access to every MCP server the parent was granted.
build_sub_agent_crd_with_labelsemitsspec.governancebut never copiesgovernance.mcpServerRefs, so e.g. a Playwright-MCP parent spawns a child sandbox with no browser tools. (Reported by Lachie: a skill run as a sub-agent couldn't reach the Playwright MCP server — labels/egressModewere inherited, but MCP access was not.)Fix
The spawn path already fetches the parent CR for label inheritance; it now also extracts the parent's effective
governance.mcpServerRefsand overlays them onto the child:parent_mcp_server_refs()readsspec.governance.mcpServerRefs, lifting the deprecated singularmcpServerRefinto plural form — mirroringGovernanceConfig::effective_mcp_server_refson the controller side.McpServerCRs and<parent>-inference/-toolpolicyalready live), so they resolve verbatim. The controller then mirrors the JWKS/signing material and derives the MCP egress rule for the child exactly as it does for the parent — no per-childMcpServerCR or manifest edit.Tests
5 new tests in a sibling
mcp_inherit_test.rssubmodule (mirrors the existingdev_profile_test.rspattern, keepsspawn/mod.rslean): plural read, singular-shim lift, plural-wins precedence, empty/absent cases, and the end-to-end child-governance overlay. All 21 spawn tests pass; clippy clean.Housekeeping
spawn/mod.rsphase0 LOC cap bumped 1400 → 1450 for the new production logic (entry already hadallow_grow: true; note updated).docs/mcp.md: new "Sub-agents inherit MCP access" section + troubleshooting row.docs/getting-started.md: de-pinned the install to@kars-runtime/cli@latestand removed the hardcodedv0.1.18so the quickstart doesn't drift every release.Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com