docs(openrouter): document auxiliary.<task>.extra_body for OR routing and Pareto (#22844)

The plumbing for setting OpenRouter provider preferences and the Pareto Code
router on auxiliary tasks already exists — auxiliary.<task>.extra_body is
forwarded verbatim by call_llm() / async_call_llm(). It just wasn't documented,
so users who wanted (e.g.) Pareto Code routing for compression but the strongest
coder for the main agent had no way to discover the escape hatch.

- hermes_cli/config.py: expand the auxiliary section header with a YAML
  example showing provider routing plus plugins under extra_body, and an
  explicit note that main-agent provider_routing / openrouter.min_coding_score
  do NOT propagate to aux calls (each task is independent by design)
- website/docs/user-guide/configuration.md: new 'OpenRouter routing and
  Pareto Code for auxiliary tasks' subsection with worked example
- website/docs/integrations/providers.md: cross-link from the Pareto Code
  Router section to the aux-side doc

E2E verified that auxiliary.<task>.extra_body reaches the OpenRouter API with
the configured provider routing and plugins blocks intact.

hermes_cli/config.py

@@ -731,6 +731,26 @@ DEFAULT_CONFIG = {
     # Empty model = use provider's default auxiliary model.
     # All tasks fall back to openrouter:google/gemini-3-flash-preview if
     # the configured provider is unavailable.
+    #
+    # extra_body: forwarded verbatim as request body fields on every aux call
+    # for that task. Use this to set provider-specific knobs (independent of
+    # main-agent settings). On OpenRouter you can set provider routing prefs
+    # and the Pareto Code coding-score floor here. Example:
+    #
+    #   auxiliary:
+    #     compression:
+    #       provider: openrouter
+    #       model: openrouter/pareto-code
+    #       extra_body:
+    #         provider:           # OpenRouter provider routing
+    #           order: [anthropic, google]
+    #           sort: throughput  # or price | latency
+    #         plugins:            # OpenRouter Pareto Code router
+    #           - id: pareto-router
+    #             min_coding_score: 0.5
+    #
+    # Each aux task is independent — main-agent provider_routing and
+    # openrouter.min_coding_score do NOT propagate to aux calls by design.
     "auxiliary": {
         "vision": {
             "provider": "auto",    # auto | openrouter | nous | codex | custom

website/docs/integrations/providers.md

@@ -1391,6 +1391,7 @@ Notes:
 - Set to empty string (or remove the line) to let OpenRouter pick the strongest available coder — its documented behavior when the plugins block is omitted.
 - Selection is deterministic per score on a given day, but the actual model chosen can shift as the Pareto frontier moves (new models, benchmark updates).
 - See OpenRouter's [Pareto Router docs](https://openrouter.ai/docs/guides/routing/routers/pareto-router) for the full router behavior.
+- To use the Pareto Code router for a specific **auxiliary task** (compression, vision, etc.) instead of the main agent, set `extra_body.plugins` under that task — see [Auxiliary Models → OpenRouter routing & Pareto Code for auxiliary tasks](/docs/user-guide/configuration#openrouter-routing--pareto-code-for-auxiliary-tasks).
 
 ## Fallback Model
 

website/docs/user-guide/configuration.md

@@ -931,6 +931,28 @@ Use `extra_body` only when your provider documents OpenAI-compatible request-bod
 `extra_body` is only effective when your provider actually supports the field you send. If the provider does not expose a native OpenAI-compatible reasoning-off flag, Hermes cannot synthesize one on its behalf.
 :::
 
+### OpenRouter routing & Pareto Code for auxiliary tasks
+
+When an auxiliary task resolves to OpenRouter (either explicitly or via `provider: "main"` while your main agent is on OpenRouter), the main agent's `provider_routing` and `openrouter.min_coding_score` settings **do not propagate** — by design, each auxiliary task is independent. To set OpenRouter provider preferences or use the [Pareto Code router](/docs/integrations/providers#openrouter-pareto-code-router) for a specific aux task, set them per-task via `extra_body`:
+
+```yaml
+auxiliary:
+  compression:
+    provider: openrouter
+    model: openrouter/pareto-code         # use the Pareto Code router for this task
+    extra_body:
+      provider:                            # OpenRouter provider routing prefs
+        order: [anthropic, google]         # try these providers in order
+        sort: throughput                   # or "price" | "latency"
+        # only: [anthropic]                # restrict to a specific provider
+        # ignore: [deepinfra]              # exclude specific providers
+      plugins:                             # OpenRouter Pareto Code router knob
+        - id: pareto-router
+          min_coding_score: 0.5            # 0.0–1.0; higher = stronger coders
+```
+
+The shape mirrors what OpenRouter accepts in the chat completions request body. Hermes forwards the entire `extra_body` verbatim, so any other OpenRouter request-body field documented at [openrouter.ai/docs](https://openrouter.ai/docs) works the same way.
+
 ### Changing the Vision Model
 
 To use GPT-4o instead of Gemini Flash for image analysis: