feat: Knowledge Agents — queryable corpora from claude-mem (#1653)

* feat: add knowledge agent types, store, builder, and renderer

Phase 1 of Knowledge Agents feature. Introduces corpus compilation
pipeline that filters observations from the database into portable
corpus files stored at ~/.claude-mem/corpora/.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add corpus CRUD HTTP endpoints and wire into worker service

Phase 2 of Knowledge Agents. Adds CorpusRoutes with 5 endpoints
(build, list, get, delete, rebuild) and registers them during
worker background initialization alongside SearchRoutes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add KnowledgeAgent with V1 SDK prime/query/reprime

Phase 3 of Knowledge Agents. Uses Agent SDK V1 query() with
resume and disallowedTools for Q&A-only knowledge sessions.
Auto-reprimes on session expiry. Adds prime, query, and reprime
HTTP endpoints to CorpusRoutes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: add MCP tools and skill for knowledge agents

Phase 4 of Knowledge Agents. Adds build_corpus, list_corpora,
prime_corpus, and query_corpus MCP tools delegating to worker
HTTP endpoints. Includes /knowledge-agent skill with workflow docs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: handle SDK process exit in KnowledgeAgent, add e2e test

The Agent SDK may throw after yielding all messages when the
Claude process exits with a non-zero code. Now tolerates this
if session_id/answer were already captured. Adds comprehensive
e2e test script (31 assertions) orchestrated via tmux-cli.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: use settings model ID instead of hardcoded model in KnowledgeAgent

Reads CLAUDE_MEM_MODEL from user settings via getModelId(), matching
the existing SDKAgent pattern. No more hardcoded model assumptions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: improve knowledge agents developer experience

Add public documentation page, rebuild/reprime MCP tools, and actionable
error messages. DX review scored knowledge agents 4/10 — core engineering
works (31/31 e2e) but the feature was invisible. This addresses
discoverability (docs, cross-links), API completeness (missing MCP tools),
and error quality (fix/example fields in error responses).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: add quick start guide to knowledge agents page

Covers the three main use cases upfront: creating an agent, asking a
single question, and starting a fresh conversation with reprime. Includes
keeping-it-current section for rebuild + reprime workflow.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address code review issues — path traversal, session safety, prompt injection

- Block path traversal in CorpusStore with alphanumeric name validation and resolved path check
- Harden system prompt against instruction injection from untrusted corpus content
- Validate question field as non-empty string in query endpoint
- Only persist session_id after successful prime (not null on failure)
- Persist refreshed session_id after query execution
- Only auto-reprime on session resume errors, not all query failures
- Add fenced code block language tags to SKILL.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address remaining code review issues — e2e robustness, MCP validation, docs

- Harden e2e curl wrappers with connect-timeout, fallback to HTTP 000 on transport failure
- Use curl_post wrapper consistently for all long-running POST calls
- Add runtime name validation to all corpus MCP tool handlers
- Fix docs: soften hallucination guarantee to probabilistic claim
- Fix architecture diagram: add missing rebuild_corpus and reprime_corpus tools

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: enforce string[] type in safeParseJsonArray for corpus data integrity

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: add blank line before fenced code blocks in SKILL.md maintenance section

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/public/introduction.mdx

@@ -33,6 +33,7 @@ Restart Claude Code. Context from previous sessions will automatically appear in
 - 🌐 **Multilingual Modes** - Supports 28 languages (Spanish, Chinese, French, Japanese, etc.)
 - 🎭 **Mode System** - Switch between workflows (Code, Email Investigation, Chill)
 - 🔍 **MCP Search Tools** - Query your project history with natural language
+- 🧠 **Knowledge Agents** - Build queryable "brains" from your observation history
 - 🌐 **Web Viewer UI** - Real-time memory stream visualization at http://localhost:37777
 - 🔒 **Privacy Control** - Use `<private>` tags to exclude sensitive content from storage
 - ⚙️ **Context Configuration** - Fine-grained control over what context gets injected
@@ -115,4 +116,7 @@ See [Architecture Overview](architecture/overview) for details.
   <Card title="Search Tools" icon="magnifying-glass" href="/usage/search-tools">
     Query your project history
   </Card>
+  <Card title="Knowledge Agents" icon="brain" href="/usage/knowledge-agents">
+    Build queryable corpora from your history
+  </Card>
 </CardGroup>