docs: per-model reasoning guide, config catalog, and the feature's Agent Note

The user guide's model-catalog section teaches the three new knobs at
task altitude — declare levels per model, pick the reasoning dialect,
reshape catalog models with modelOverrides — with the settings.yaml
example exercising all of them, plus an UNSUPPORTED_REASONING_EFFORT
troubleshooting row. The generated plugin config catalog picks up the
new Config fields, and the bilingual Agent Note records the decision,
the alternatives considered, and the schemastery materialization
constraint that chose false over {} as the disable spelling.

docs/config-catalog.md

@@ -767,6 +767,22 @@ export interface PiAiProviderProfile {
    * unset fields from the installed model of the same id.
    */
   models?: PiAiModelProfile[]
+  /**
+   * Installed-catalog customizations by model id: each entry reshapes that
+   * one model with the same fields a {@link models} entry takes, while the
+   * rest of the catalog keeps serving untouched. Only meaningful on a catalog
+   * route with no `models` list — `models` already replaces the catalog, so
+   * an override beside it, on a route the catalog does not ship, or naming a
+   * model the catalog does not describe is refused rather than skipped.
+   */
+  modelOverrides?: Record<string, PiAiModelOverride>
+  /**
+   * Reasoning-dispatch switches for every `openai-completions` model on this
+   * route; each model's own `compat` overrides per field. What neither sets
+   * keeps the installed catalog entry's value, then pi-ai's baseURL-derived
+   * detection.
+   */
+  compat?: PiAiCompatProfile
   /**
    * Context capacity for a model this route lists that neither the entry nor
    * the installed catalog sizes (default 262,144). A guess by construction, so
@@ -814,12 +830,70 @@ export interface PiAiModelProfile {
    * default on its own.
    */
   maxTokens?: number
+  /**
+   * Selectable reasoning efforts. Absent inherits the installed catalog
+   * entry's capability (a hand-declared model has none and does not reason);
+   * `false` declares a non-reasoning model, which is how a profile strips
+   * reasoning from a catalog model its gateway cannot serve; a non-empty dict
+   * declares the offered levels and their wire spellings.
+   */
+  reasoningEfforts?: false | PiAiReasoningEfforts
+  /** Reasoning-dispatch switches for this model, winning over the route's. */
+  compat?: PiAiCompatProfile
 }
+
+/**
+ * Customization of one installed catalog model, keyed by its id in the
+ * route's `modelOverrides` dict — the same fields a `models` entry may set,
+ * with the id living in the key. Unlike a `models` list, overrides leave the
+ * rest of the catalog serving untouched, which is what makes "correct one
+ * model, keep the other thirty-seven" a three-line edit.
+ */
+export type PiAiModelOverride = Omit<PiAiModelProfile, 'id'>
+
+/**
+ * Reasoning-dispatch compatibility switches, set on the route (its models'
+ * default) or per model (winning over the route). Only the switches pi-ai's
+ * reasoning dispatch reads are offered; the rest of pi-ai's compat surface
+ * keeps its baseURL-derived auto-detection. pi-ai types both fields only on
+ * `OpenAICompletionsCompat` — the other wire protocols carry their reasoning
+ * shape in the protocol itself — so resolution rejects a model-level switch
+ * anywhere else, while a route-level default skips past models it cannot fit.
+ */
+export interface PiAiCompatProfile {
+  /** Reasoning parameter shape the endpoint expects; absent keeps the catalog entry's, then pi-ai's baseURL-derived guess. */
+  thinkingFormat?: PiAiThinkingFormat
+  /** Whether the endpoint accepts `reasoning_effort`; absent keeps the catalog entry's, then pi-ai's baseURL-derived guess. */
+  supportsReasoningEffort?: boolean
+}
+
+/**
+ * Selectable reasoning efforts for one model: each key is a level the model
+ * offers (and selectors show), and its value is the wire spelling dispatch
+ * sends for it. `off` alone may leave its value empty — "supported, send
+ * nothing" — because for most providers not thinking is the parameter's
+ * absence; every other declared level must name a wire value. A level absent
+ * from the dict is not offered.
+ */
+export type PiAiReasoningEfforts = Partial<Record<ModelThinkingLevel, string | null>>
+
+/** One reasoning-dispatch wire format a profile may name. */
+export type PiAiThinkingFormat = Exclude<PiThinkingFormat, WithheldThinkingFormat>
+
+/** The `compat.thinkingFormat` spellings pi-ai accepts on an `openai-completions` model. */
+type PiThinkingFormat = NonNullable<OpenAICompletionsCompat['thinkingFormat']>
+
+/**
+ * pi-ai thinking formats a profile cannot name: both drive the request through
+ * `chatTemplateKwargs`, which this configuration does not expose, so offering
+ * them would hand back a format with nothing to say.
+ */
+type WithheldThinkingFormat = 'chat-template' | 'qwen-chat-template'
 ```
 
-Depends on: `CacheRetention` (`@earendil-works/pi-ai`) · `ModelThinkingLevel` (`@earendil-works/pi-ai`) · [`RetryPolicyConfig`](../packages/llm/llm/src/index.ts) · `ThinkingBudgets` (`@earendil-works/pi-ai`) · `Transport` (`@earendil-works/pi-ai`)
+Depends on: `CacheRetention` (`@earendil-works/pi-ai`) · `ModelThinkingLevel` (`@earendil-works/pi-ai`) · `OpenAICompletionsCompat` (`@earendil-works/pi-ai`) · [`RetryPolicyConfig`](../packages/llm/llm/src/index.ts) · `ThinkingBudgets` (`@earendil-works/pi-ai`) · `Transport` (`@earendil-works/pi-ai`)
 
-Source: [`packages/llm/llm-pi-ai/src/config.ts:126`](../packages/llm/llm-pi-ai/src/config.ts)
+Source: [`packages/llm/llm-pi-ai/src/config.ts:148`](../packages/llm/llm-pi-ai/src/config.ts)
 
 ## `@deepseek-ai/dsh-llm-replay`