#19022: memory: support per-agent QMD collection paths

## Summary - **Problem:** QMD backend resolves custom collection paths from global `memory.qmd.paths` only — all agents share the same collections in multi-agent setups. - **Why it matters:** Agent-specific knowledge leaks into unrelated agents' search results, reducing relevance. The builtin backend already supports per-agent scoping via `memorySearch.extraPaths`, but QMD has no equivalent. - **What changed:** Added optional `qmd.paths` to per-agent config (`AgentConfig`). `resolveMemoryBackendConfig()` now appends per-agent paths after global paths. - **What did NOT change:** Global `memory.qmd.paths` behavior is untouched. Default memory paths (`MEMORY.md`, `memory/*.md`) remain workspace-scoped as before. No changes to builtin backend or `memorySearch.extraPaths`. ## Change Type (select all) - [x] Feature ## Scope (select all touched areas) - [x] Memory / storage ## Linked Issue/PR - Closes #19005 ## User-visible / Behavior Changes New optional config key `agents.list[].qmd.paths` (array of `MemoryQmdIndexPath`). Per-agent paths are appended to global `memory.qmd.paths`. No behavior change for existing configs without the new key. ## Security Impact (required) - New permissions/capabilities? `No` - Secrets/tokens handling changed? `No` - New/changed network calls? `No` - Command/tool execution surface changed? `No` - Data access scope changed? `No` ## Repro + Verification ### Environment - Runtime: Node 22+ / Bun ### Steps 1. Configure two agents with different `qmd.paths` in config 2. Run `resolveMemoryBackendConfig` for each agent 3. Verify collections include global + agent-specific paths ### Expected - Each agent's resolved collections contain global paths plus only their own per-agent paths ### Actual - Confirmed via unit test ## Evidence - [x] Failing test/log before + passing after — new test `merges per-agent qmd.paths with global paths` (8/8 passing) ## Human Verification (required) - Verified scenarios: new test covers merge behavior for agent with per-agent paths and agent without - Edge cases checked: agent with no `qmd` config gets only global paths; collection name deduplication still works - What you did **not** verify: live gateway with real QMD command ## Compatibility / Migration - Backward compatible? `Yes` - Config/env changes? `No` (additive optional key) - Migration needed? `No` ## Failure Recovery (if this breaks) - How to disable/revert: remove `qmd` key from agent configs; behavior reverts to global-only paths - Known bad symptoms: unexpected collections in agent search results ## Risks and Mitigations None — additive config key with no impact on existing setups. <!-- greptile_comment --> <h3>Greptile Summary</h3> Adds per-agent QMD collection paths (`agents.list[].qmd.paths`) that are appended after global `memory.qmd.paths` during resolution, enabling agent-specific knowledge scoping in multi-agent setups. - The core resolution logic in `backend-config.ts` is clean and reuses the existing `resolveCustomPaths` helper — collection name deduplication via `nameSet` is preserved. - The new test covers the key scenarios (agent with per-agent paths, agent without). - **Critical issue:** The `qmd` field was added to the `AgentConfig` TypeScript type but **not** to the `AgentEntrySchema` Zod schema in `src/config/zod-schema.agent-runtime.ts`. That schema uses `.strict()`, which means any config that uses the new `agents.list[].qmd.paths` key will fail validation with an "unrecognized key" error at runtime. The Zod schema must be updated for this feature to work. <h3>Confidence Score: 2/5</h3> - This PR will not work as intended due to a missing Zod schema update — configs using the new key will be rejected at runtime. - The implementation logic is correct and the test passes, but the Zod validation schema for agent entries uses `.strict()` and was not updated to include the new `qmd` field. This means the feature is dead on arrival: any user config that sets `agents.list[].qmd.paths` will fail config validation before the resolution code ever runs. - Pay close attention to `src/config/zod-schema.agent-runtime.ts` — the `AgentEntrySchema` needs a `qmd` field added to match the TypeScript type change in `types.agents.ts`. _{Last reviewed commit: 80f4a45} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->