feat(session-title): add fallback and model providers

packages/session-title/session-title-first-message-llm/src/index.ts

@@ -0,0 +1,40 @@
+/** First-human-message model provider for `ctx.sessionTitle`. */
+
+import type { Context } from 'cordis'
+import z from 'schemastery'
+import {
+  registerSessionTitleLlmProvider,
+  SessionTitleLlmConfigFields,
+} from '@deepseek-ai/dsh-session-title-llm'
+import type { SessionTitleLlmConfig } from '@deepseek-ai/dsh-session-title-llm'
+
+export const name = 'session-title-first-message-llm'
+export const inject = ['sessionTitle', 'llm']
+
+/** Required LLM policy; this plugin adds no defaults. */
+export type Config = SessionTitleLlmConfig
+/** Loader schema shared with the all-messages provider. */
+/* jscpd:ignore-start -- Loader requires each plugin to export its own statically walkable schema; the field validators remain shared. */
+export const Config: z<Config> = z.object({
+  targetWords: SessionTitleLlmConfigFields.targetWords,
+  targetCjkCharacters: SessionTitleLlmConfigFields.targetCjkCharacters,
+  maxInputBytes: SessionTitleLlmConfigFields.maxInputBytes,
+  maxOutputTokens: SessionTitleLlmConfigFields.maxOutputTokens,
+  timeoutMs: SessionTitleLlmConfigFields.timeoutMs,
+  provider: SessionTitleLlmConfigFields.provider,
+  model: SessionTitleLlmConfigFields.model,
+})
+/* jscpd:ignore-end */
+
+/**
+ * Register the first-message model provider.
+ * @param ctx - context exposing session-title and LLM services.
+ * @param config - required route, target, byte, token, and timeout policy.
+ */
+export function apply(ctx: Context, config: Config): void {
+  registerSessionTitleLlmProvider(ctx, config, name, 'first-message', (messages) => {
+    const first = messages[0]
+    if (first === undefined) throw new Error('first-message title provider requires one human message')
+    return [first]
+  })
+}