feat(client): increment forked session titles

packages/client/runtime/src/client/contract/sessions.ts

@@ -32,12 +32,14 @@ export interface ISessions {
   /**
    * Fork a session from a completed-turn prefix of the source; on resolution
    * the child is in the list store and `open()` can target it.
-   * @param opts - source session id and the optional event seq anchoring the
+   * @param opts - source session id, the optional event seq anchoring the
    *   cut (the boundary is the first turn/end at or after it; an in-log
-   *   anchor in an open turn is unavailable rather than clipped backward).
+   *   anchor in an open turn is unavailable rather than clipped backward),
+   *   and whether to increment an inherited durable title before resolving.
    * @returns the child session id.
+   * @throws when the fork fails, or when a requested child-title rename fails after creation.
    */
-  fork(opts: { sessionId: SessionId; atSeq?: number }): Promise<SessionId>
+  fork(opts: { sessionId: SessionId; atSeq?: number; increaseTitle?: boolean }): Promise<SessionId>
   /**
    * Register a per-session standard-props provider (hooks become `use<Name>`
    * selector hooks on the render side; props spread verbatim).

packages/client/runtime/src/client/sessions/service.ts

@@ -137,6 +137,24 @@ function displayTitleOf(title: string | undefined, cwd: string | undefined, id:
   return id
 }
 
+/**
+ * Increment a trailing fork number while preserving its half-width or
+ * full-width parentheses; an unnumbered title starts with ` (1)`.
+ * @param title - source session's durable title.
+ * @returns the title assigned to the fork child.
+ */
+function increasedForkTitle(title: string): string {
+  const ascii = /^(.*?)\((\d+)\)$/u.exec(title)
+  if (ascii?.[1] !== undefined && ascii[2] !== undefined) {
+    return `${ascii[1]}(${BigInt(ascii[2]) + 1n})`
+  }
+  const fullWidth = /^(.*?)（(\d+)）$/u.exec(title)
+  if (fullWidth?.[1] !== undefined && fullWidth[2] !== undefined) {
+    return `${fullWidth[1]}（${BigInt(fullWidth[2]) + 1n}）`
+  }
+  return `${title} (1)`
+}
+
 interface ScopeRecord {
   fiber: Fiber
   ctx: Context
@@ -337,17 +355,36 @@ export class SessionsService implements ISessions {
    * Fork a session from a completed-turn prefix of the source (same
    * synchronous-addressability guarantee as {@link SessionsService.create}:
    * on resolution the child is in the list store and open() can target it).
-   * @param opts - source session id and the optional event seq anchoring the
+   * @param opts - source session id, the optional event seq anchoring the
    *   cut (the boundary is the first turn/end at or after it; an in-log
-   *   anchor in an open turn is unavailable rather than clipped backward).
+   *   anchor in an open turn is unavailable rather than clipped backward),
+   *   and whether to increment an inherited durable title before resolving.
    * @returns the child session id.
    * @throws {SessionForkError} with the source id.
+   * @throws {Error} when a requested child-title rename fails after creation.
    */
-  async fork(opts: { sessionId: SessionId; atSeq?: number }): Promise<SessionId> {
-    const result = await this.manager.fork(opts)
+  async fork(opts: {
+    sessionId: SessionId
+    atSeq?: number
+    increaseTitle?: boolean
+  }): Promise<SessionId> {
+    const sourceTitle = opts.increaseTitle
+      ? this.list.getSnapshot().byId[opts.sessionId]?.title
+      : undefined
+    const result = await this.manager.fork({
+      sessionId: opts.sessionId,
+      ...(opts.atSeq === undefined ? {} : { atSeq: opts.atSeq }),
+    })
     if (!result.ok) throw new SessionForkError(result.error, opts.sessionId)
     this.projectList()
-    return result.value.sessionId
+    const childId = result.value.sessionId
+    if (sourceTitle !== undefined) {
+      const child = this.binding(childId)?.session
+      if (child === undefined) throw new Error(`fork child "${childId}" is not locally addressable`)
+      const renamed = await child.rename(increasedForkTitle(sourceTitle))
+      if (!renamed.ok) throw new Error(`fork child rename failed: ${renamed.error.code}: ${renamed.error.message}`)
+    }
+    return childId
   }
 
   /**