1 files changed, 66 insertions, 0 deletions
diff --git a/src/features/chat/reasoning-effort.ts b/src/features/chat/reasoning-effort.ts
new file mode 100644
index 0000000..1eb77b6
--- /dev/null
+++ b/src/features/chat/reasoning-effort.ts
@@ -0,0 +1,66 @@
+import type { ReasoningEffort } from "@dispatch/transport-contract";
+
+/**
+ * Pure helpers for the reasoning-effort selector (the thinking-depth knob).
+ *
+ * The canonical ladder + resolution chain are SERVER-owned (`[email protected]`
+ * `ReasoningEffort`; per-turn override → persisted conversation value → default
+ * `"high"`). These helpers only shape the persisted value for display: a `null`
+ * from `GET /conversations/:id/reasoning-effort` means "never set ⇒ the default
+ * applies", so the selector shows `high (default)` — never "off". Zero DOM,
+ * zero Svelte.
+ */
+
+/** The canonical ladder, in ascending thinking-depth order (`[email protected]`). */
+export const REASONING_EFFORT_LEVELS: readonly ReasoningEffort[] = [
+  "low",
+  "medium",
+  "high",
+  "xhigh",
+  "max",
+];
+
+/** The server's fallback when nothing is set (the resolution chain's tail). */
+export const DEFAULT_REASONING_EFFORT: ReasoningEffort = "high";
+
+/** Narrow an untrusted string (e.g. a `<select>` value) to the ladder. */
+export function isReasoningEffort(value: string): value is ReasoningEffort {
+  return (REASONING_EFFORT_LEVELS as readonly string[]).includes(value);
+}
+
+/**
+ * The level the selector should show as selected: the persisted value, or the
+ * server default when never set (`null` = "default applies", not "off").
+ */
+export function effectiveEffort(persisted: ReasoningEffort | null): ReasoningEffort {
+  return persisted ?? DEFAULT_REASONING_EFFORT;
+}
+
+/** One `<option>` of the selector. */
+export interface EffortOption {
+  readonly value: ReasoningEffort;
+  readonly label: string;
+}
+
+/**
+ * The selector's options: every ladder level, with the server default marked
+ * `(default)` so a never-set conversation reads "high (default)".
+ */
+export function effortOptions(): readonly EffortOption[] {
+  return REASONING_EFFORT_LEVELS.map((level) => ({
+    value: level,
+    label: level === DEFAULT_REASONING_EFFORT ? `${level} (default)` : level,
+  }));
+}
+
+// ── Injected port (consumer-defines-port; the composition root adapts the
+//    store's `PUT /conversations/:id/reasoning-effort` to this shape). ────────
+
+/** Outcome of `PUT /conversations/:id/reasoning-effort`. */
+export type ReasoningEffortSaveResult =
+  | { readonly ok: true; readonly reasoningEffort: ReasoningEffort }
+  | { readonly ok: false; readonly error: string };
+
+export type SaveReasoningEffort = (
+  level: ReasoningEffort,
+) => Promise<ReasoningEffortSaveResult | null>;