feat: add litellm MCP server entry and enhance Rule 15 validation

- Added litellm MCP server entry to mcp_servers section with correct URL
  (https://litellm.sysloggh.net/mcp) and header format
- Updated Rule 15 to be more specific about endpoint validation and
  header requirements (REAL keys, not env-var references)
- Added MCP Server Configuration section with implementation details
- Documented the 2026-08-07 Tanko incident where ra-h-os was pointing
  to litellm endpoint with env header causing 401 floods
- Updated frontmatter to reflect the changes

Fixes: #keyless-mcp-incident-20260807
Refs: Rule 15 (MCP Endpoint and Header Validation)

hermes-config-template.prose.md

@@ -5,7 +5,8 @@ description: >
   Standard Hermes configuration template for Syslog Solution LLC agents.
   Enforces shared infrastructure setup (Firecrawl, SearXNG, local models,
   RA-H OS MCP) while keeping agent-specific API keys and model choices.
-  UPDATED 2026-08-07: Added Rule 15 (MCP Validation) from the 2026-08-07 keyless-MCP incident.
+  UPDATED 2026-08-07: Added litellm MCP server entry; updated Rule 15 (MCP Validation)
+  to enforce REAL key headers (not env-vars) from the 2026-08-07 keyless-MCP incident.
   Added Rule 12 (Context-Issue Diagnostic) + Rule 13 (.env fallback enforcement) from the
   2026-07-16 Mumuni root-cause investigation (WAL #1300).
   UPDATED 2026-07-12: GPU workload redistributed. Compression → Strix Halo. RTX 3090 context verified at 128K. Infisical .env fallback required (Rule 3/13).
@@ -145,6 +146,10 @@ mcp_servers:
     url: http://192.168.68.65:3100/mcp
     timeout: 120
     connect_timeout: 60
+  litellm:
+    url: https://litellm.sysloggh.net/mcp
+    headers:
+      x-litellm-api-key: "Bearer <AGENT_KEY>"   # Rule 15: must be a REAL key (sk-...), not an env-var name
 
 # ─── Compression ───
 compression:
@@ -217,6 +222,21 @@ When LiteLLM keys are regenerated (e.g., after infrastructure changes):
 3. **After update**: Restart Hermes on the agent host
 4. **Verify**: `curl -H "Authorization: Bearer sk-<KEY>" http://192.168.68.116/v1/models`
 
+## MCP Server Configuration
+
+MCP server entries in `mcp_servers:` must follow the format shown in the Template section.
+
+**Header requirements (Rule 15):**
+- Use `headers:` field with a `x-litellm-api-key` entry
+- The value must be `"Bearer <REAL_KEY>"` where `<REAL_KEY>` is a literal LiteLLM virtual key
+- Do NOT use env-var references like `$LITELLM_API_KEY` — they resolve to empty strings in
+  the static config and cause "Malformed API Key" errors (2026-08-07 Tanko incident)
+
+**Key source:**
+- Keys are stored in the Infisical vault (project=agents, env=production)
+- For template-based config generation: substitute the agent's key from the agent_keys table
+- For manual config updates: retrieve the key from the vault and insert the literal value
+
 ## Violation Classification
 
 When reporting findings, separate POLICY observations from FAULT findings:
@@ -455,14 +475,22 @@ curl -s -o /dev/null -w '%{http_code}' -H "Authorization: Bearer $K" http://192.
 - **Audit script**: Run `python3 /root/prose-contracts/audit-hermes-config.py <config.yaml>`
   before and after any config change to catch this and all other rule violations.
 
-### Rule 15: MCP Endpoint and Header Validation (ADDED 2026-08-07)
-- Every MCP server entry must point at the correct endpoint:
-  - ra-h-os = http://192.168.68.65:3100/mcp
-  - litellm = https://litellm.sysloggh.net/mcp
-- MCP entries must carry a REAL key value in the header.
-  - Avoid using env-var names like LITELLM_API_KEY in the header; they do not resolve for MCP
-    endpoints and result in "Malformed API Key" floods.
-  - Ensure the header value is the actual key (e.g., `sk-...`).
+### Rule 15: MCP Endpoint and Header Validation (UPDATED 2026-08-07)
+
+**Endpoint validation:**
+- ra-h-os must point to `http://192.168.68.65:3100/mcp`
+- litellm must point to `https://litellm.sysloggh.net/mcp`
+- Mismatched endpoints cause silent failures (e.g., 2026-08-07 incident: Tanko's config had
+  ra-h-os pointing to litellm's endpoint)
+
+**Header validation:**
+- Every MCP entry with authentication must carry a `headers:` field
+- The header value must be a REAL key (e.g., `Bearer sk-abc123...`), NOT an env-var name
+- Env-var names like `LITELLM_API_KEY` do NOT resolve in static MCP configs and cause
+  "Malformed API Key" floods (401 errors in agent gateway logs)
+- Verify: header value should match a valid LiteLLM key (test with `curl` against /v1/models)
+
+**See:** § MCP Server Configuration for implementation details and key source.
 
 ## Execution