feat(server,web,mobile): thread links name their environment and never a title (#26239)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: juliusmarminge

apps/mobile/src/features/threads/PendingUserInputCard.tsx

@@ -1,6 +1,6 @@
 import { Button } from "../../components/ui/Button";
 import { QuestionAttachments } from "./QuestionAttachments";
-import type { RuntimeRequestId } from "@t3tools/contracts";
+import type { EnvironmentId, RuntimeRequestId } from "@t3tools/contracts";
 import type { ThreadUserInputQuestion } from "@t3tools/client-runtime/state/thread-requests";
 import { useRef } from "react";
 import { Platform, Pressable, ScrollView, View, type LayoutChangeEvent } from "react-native";
@@ -23,13 +23,15 @@ import { cn } from "../../lib/cn";
 import { SelectableMarkdownText } from "../../native/SelectableMarkdownText";
 import { useOpenPullRequest } from "../../native/useOpenPullRequest";
 import { useMarkdownPreviewStyles } from "../files/FileMarkdownPreview";
+import { useLiveThreadLinkLabels } from "../../state/entities";
 import {
   isPendingUserInputOptionSelected,
   type PendingUserInput,
   type PendingUserInputDraftAnswer,
 } from "../../lib/threadActivity";
 
 export interface PendingUserInputCardProps {
+  readonly environmentId: EnvironmentId;
   readonly canOperateThread: boolean;
   readonly pendingUserInput: PendingUserInput;
   readonly maxHeight: DerivedValue<number>;
@@ -59,12 +61,13 @@ export interface PendingUserInputCardProps {
 /** Android cannot hit-test overlays beyond their parent's bounds; render its expanded card in-flow. */
 const EXPANDED_CARD_IS_OVERLAY = Platform.OS === "ios";
 
-function QuestionText(props: { readonly markdown: string }) {
+function QuestionText(props: { readonly markdown: string; readonly environmentId: EnvironmentId }) {
   const styles = useMarkdownPreviewStyles();
+  const markdown = useLiveThreadLinkLabels(props.markdown, props.environmentId);
   const openLink = useOpenPullRequest();
   return (
     <SelectableMarkdownText
-      markdown={props.markdown}
+      markdown={markdown}
       textStyle={styles.nativeTextStyle}
       onLinkPress={(href) => void openLink(href)}
     />
@@ -217,7 +220,7 @@ export function PendingUserInputCard(props: PendingUserInputCardProps) {
               <Text className="font-t3-bold text-xs uppercase tracking-[1px] text-foreground-muted">
                 {question.header}
               </Text>
-              <QuestionText markdown={question.question} />
+              <QuestionText markdown={question.question} environmentId={props.environmentId} />
               <View className="gap-2">
                 {question.options.map((option) => {
                   const optionValue = option.value ?? option.label.trim();

apps/mobile/src/features/threads/ThreadDetailScreen.tsx

@@ -1513,6 +1513,7 @@ function ThreadDetailBody(props: ThreadDetailScreenProps) {
                       ) : null}
                       {props.activePendingUserInput ? (
                         <PendingUserInputCard
+                          environmentId={props.environmentId}
                           canOperateThread={props.canOperateThread}
                           pendingUserInput={props.activePendingUserInput}
                           maxHeight={pendingUserInputMaxHeight}

apps/mobile/src/features/threads/ThreadFeed.tsx

@@ -56,7 +56,7 @@ import {
 } from "@t3tools/contracts";
 import { renderAssistantCitationsAsText } from "@t3tools/shared/assistantCitations";
 import { encodeComposerContextFragment } from "@t3tools/shared/composerContextClipboard";
-import { parseThreadLinkHref, resolveThreadLinkRef } from "@t3tools/shared/threadLinks";
+import { parseThreadLinkHref } from "@t3tools/shared/threadLinks";
 import { PROMPT_LINK_MAX_PROMPT_LENGTH } from "@t3tools/shared/promptLinks";
 import {
   parseComposerContextHref,
@@ -239,6 +239,7 @@ import {
   WORKSPACE_BASENAME_LOOKUP_LIMIT,
 } from "@t3tools/client-runtime/workspace-basename-lookup";
 import {
+  resolveThreadLink,
   useLiveThreadLinkLabels,
   useQuietThreadShell,
   useThreadChipIcons,
@@ -2255,13 +2256,16 @@ export const ThreadFeed = memo(function ThreadFeed({
     });
   };
   const resolveLinkedThread = (href: string) => {
-    const linkedThreadId = parseThreadLinkHref(href);
-    if (!linkedThreadId) return null;
-    const source = scopeThreadRef(props.environmentId, linkedThreadId);
-    return (
-      resolveThreadLinkRef(source, appAtomRegistry.get(environmentThreadShells.threadRefsAtom)) ??
-      source
+    const link = parseThreadLinkHref(href);
+    if (!link) return null;
+    const resolved = resolveThreadLink(
+      (atom) => appAtomRegistry.get(atom),
+      link,
+      props.environmentId,
     );
+    if (resolved !== null || link.environmentId !== null) return resolved;
+    // A v1 link names no environment, so it falls back to this message's.
+    return scopeThreadRef(props.environmentId, link.threadId);
   };
   const onMarkdownLinkPress = (href: string, imageEmbed = false) => {
     markdownLinkRequest.current?.abort();
@@ -2273,12 +2277,14 @@ export const ThreadFeed = memo(function ThreadFeed({
       if (instructionsPath) openSkillInstructions(instructionsPath);
       return;
     }
-    const target = resolveLinkedThread(href);
-    if (target) {
-      openLinkedThread({
-        environmentId: String(target.environmentId),
-        threadId: String(target.threadId),
-      });
+    if (parseThreadLinkHref(href)) {
+      const target = resolveLinkedThread(href);
+      if (target) {
+        openLinkedThread({
+          environmentId: String(target.environmentId),
+          threadId: String(target.threadId),
+        });
+      }
       return;
     }
     const media = resolveMarkdownMediaPreview(href, {

apps/mobile/src/lib/enrichedLinkPresentation.test.ts

@@ -51,10 +51,12 @@ describe("Enriched link presentation", () => {
   });
 
   it("presents thread links as thread chips and leaves other links alone", () => {
-    expect(enrichedThreadLinkPresentation("t3-thread://v1/thread%3Aproject%3A1")).toEqual({
-      accent: "#009c96",
-      icon: { kind: "chip", name: "messages-square" },
-    });
+    for (const href of ["t3-thread://v1/thread%3Aproject%3A1", "t3-thread://v2/env/thread_1"]) {
+      expect(enrichedThreadLinkPresentation(href), href).toEqual({
+        accent: "#009c96",
+        icon: { kind: "chip", name: "messages-square" },
+      });
+    }
     for (const href of [
       "https://github.com/example/repo/pull/7",
       "https://example.com",
@@ -70,7 +72,7 @@ describe("Enriched link presentation", () => {
     expect(
       threadChipTargets(
         here,
-        "See [A](t3-thread://v1/thread_a), [A again](t3-thread://v1/thread_a) and [B](t3-thread://v1/thread_b).",
+        "See [A](t3-thread://v1/thread_a), [A again](t3-thread://v1/thread_a), [B](t3-thread://v1/thread_b) and [D](t3-thread://v2/env-there/thread_d).",
         [
           {
             version: 1,
@@ -86,6 +88,12 @@ describe("Enriched link presentation", () => {
     ).toEqual([
       { href: "t3-thread://v1/thread_a", environmentId: here, threadId: "thread_a", link: true },
       { href: "t3-thread://v1/thread_b", environmentId: here, threadId: "thread_b", link: true },
+      {
+        href: "t3-thread://v2/env-there/thread_d",
+        environmentId: there,
+        threadId: "thread_d",
+        link: true,
+      },
       {
         href: "t3-context://v1/thread/thr1",
         environmentId: there,

apps/mobile/src/lib/enrichedLinkPresentation.ts

@@ -58,9 +58,16 @@ export function threadChipTargets(
 ): ReadonlyArray<ThreadChipTarget> {
   const targets = new Map<string, ThreadChipTarget>();
   if (hasThreadLinks(markdown)) {
-    for (const [, href = ""] of markdown.matchAll(/\]\((t3-thread:\/\/v1\/[^\s)]+)\)/g)) {
-      const threadId = parseThreadLinkHref(href);
-      if (threadId) targets.set(href, { href, environmentId, threadId, link: true });
+    for (const [, href = ""] of markdown.matchAll(/\]\((t3-thread:\/\/v[12]\/[^\s)]+)\)/g)) {
+      const link = parseThreadLinkHref(href);
+      if (link) {
+        targets.set(href, {
+          href,
+          environmentId: link.environmentId ?? environmentId,
+          threadId: link.threadId,
+          link: true,
+        });
+      }
     }
   }
   for (const record of records ?? []) {

apps/mobile/src/state/entities.ts

@@ -17,9 +17,13 @@ import {
 } from "@t3tools/contracts";
 import { scopeThreadRef } from "@t3tools/client-runtime/environment";
 import {
+  guessThreadLinkRef,
   hasThreadLinks,
+  parseThreadLinkHref,
   relabelThreadLinks,
-  resolveThreadLinkRef,
+  threadLinkCandidates,
+  threadLinkRefs,
+  type ThreadLink,
 } from "@t3tools/shared/threadLinks";
 import * as Option from "effect/Option";
 import * as Schema from "effect/Schema";
@@ -45,26 +49,35 @@ const EMPTY_SERVER_CONFIG_ATOM = Atom.make<ServerConfig | null>(null).pipe(
 const EMPTY_THREAD_ATOM = Atom.make<EnvironmentThread | null>(null).pipe(
   Atom.withLabel("mobile-thread:empty"),
 );
-const EMPTY_THREAD_TITLES: ReadonlyMap<ThreadId, string> = new Map();
-const EMPTY_THREAD_TITLES_ATOM = Atom.make(EMPTY_THREAD_TITLES).pipe(
-  Atom.withLabel("mobile-thread-titles:empty"),
+const EMPTY_THREAD_LINK_TITLES_ATOM = Atom.make<ReadonlyMap<string, string>>(new Map()).pipe(
+  Atom.withLabel("mobile-thread-link-titles:empty"),
 );
 
-const threadTitlesAtom = Atom.family((environmentId: EnvironmentId) => {
-  let previous = EMPTY_THREAD_TITLES;
+const decodeThreadKey = Schema.decodeUnknownSync(Schema.Tuple([EnvironmentId, ThreadId]));
+const threadKey = (ref: ScopedThreadRef) => JSON.stringify([ref.environmentId, ref.threadId]);
+
+// Null when this client doesn't know the thread. Keyed, so a link never walks an environment's threads.
+const threadTitleAtom = Atom.family((key: string) => {
+  const ref = scopeThreadRef(...decodeThreadKey(JSON.parse(key)));
+  return Atom.make((get) => get(environmentThreadShells.threadShellAtom(ref))?.title ?? null).pipe(
+    Atom.withLabel(`mobile-thread-title:${key}`),
+  );
+});
+
+const decodeThreadKeys = Schema.decodeUnknownSync(Schema.Array(Schema.String));
+
+const threadLinkTitlesAtom = Atom.family((key: string) => {
+  const refKeys = decodeThreadKeys(JSON.parse(key));
   return Atom.make((get) => {
-    const index = get(environmentThreadShells.environmentThreadIndexAtom(environmentId));
-    const unchanged =
-      index.size === previous.size &&
-      Array.from(index).every(([threadId, shell]) => previous.get(threadId) === shell.title);
-    if (!unchanged) {
-      previous = new Map(Array.from(index, ([threadId, shell]) => [threadId, shell.title]));
+    const titles = new Map<string, string>();
+    for (const refKey of refKeys) {
+      const title = get(threadTitleAtom(refKey));
+      if (title !== null) titles.set(refKey, title);
     }
-    return previous;
-  }).pipe(Atom.withLabel(`mobile-thread-titles:${environmentId}`));
+    return titles;
+  }).pipe(Atom.withLabel(`mobile-thread-link-titles:${key}`));
 });
 
-const decodeThreadKey = Schema.decodeUnknownSync(Schema.Tuple([EnvironmentId, ThreadId]));
 const decodeThreadChipTargets = Schema.decodeUnknownSync(
   Schema.Array(
     Schema.Struct({
@@ -118,13 +131,11 @@ const threadChipIconsAtom = Atom.family((key: string) => {
   return Atom.make((get) => {
     const icons = new Map<string, string>();
     for (const target of targets) {
-      const source = scopeThreadRef(target.environmentId, target.threadId);
-      const ref = target.link
-        ? (resolveThreadLinkRef(source, get(environmentThreadShells.threadRefsAtom)) ?? source)
-        : source;
-      const icon = get(
-        threadProjectChipIconAtom(JSON.stringify([ref.environmentId, ref.threadId])),
-      );
+      const link = target.link ? parseThreadLinkHref(target.href) : null;
+      const ref =
+        (link ? resolveThreadLink(get, link, target.environmentId) : null) ??
+        scopeThreadRef(target.environmentId, target.threadId);
+      const icon = get(threadProjectChipIconAtom(threadKey(ref)));
       if (icon) icons.set(target.href, icon);
     }
     return icons;
@@ -190,11 +201,26 @@ export function useChildThreadInputs(ref: ScopedThreadRef) {
 
 export function useLiveThreadLinkLabels(markdown: string, environmentId: EnvironmentId): string {
   const titles = useAtomValue(
-    hasThreadLinks(markdown) ? threadTitlesAtom(environmentId) : EMPTY_THREAD_TITLES_ATOM,
+    hasThreadLinks(markdown)
+      ? threadLinkTitlesAtom(JSON.stringify(threadLinkRefs(markdown, environmentId).map(threadKey)))
+      : EMPTY_THREAD_LINK_TITLES_ATOM,
+  );
+  return relabelThreadLinks(markdown, environmentId, (ref) => titles.get(threadKey(ref)));
+}
+
+/** Keyed reads; every thread is read only to place a v1 link its message's environment lacks. */
+export function resolveThreadLink(
+  read: <A>(atom: Atom.Atom<A>) => A,
+  link: ThreadLink,
+  messageEnvironmentId: EnvironmentId,
+): ScopedThreadRef | null {
+  const known = threadLinkCandidates(link, messageEnvironmentId).find(
+    (ref) => read(threadTitleAtom(threadKey(ref))) !== null,
   );
-  return titles.size === 0
-    ? markdown
-    : relabelThreadLinks(markdown, (threadId) => titles.get(threadId));
+  if (known) return known;
+  return link.environmentId === null
+    ? guessThreadLinkRef(link, read(environmentThreadShells.threadRefsAtom))
+    : null;
 }
 
 export function useThreadChipIcons(

apps/server/src/mcp/OrchestratorMcpService.ts

@@ -1,5 +1,6 @@
 import {
   CommandId,
+  type EnvironmentId,
   type RunId,
   isProviderAvailable,
   MessageId,
@@ -748,13 +749,14 @@ function threadPullRequests(
 }
 
 function listItemFromShell(
+  environmentId: EnvironmentId,
   shell: OrchestrationV2ThreadShell,
   nowMs: number,
 ): OrchestratorMcpThreadListItem {
   return {
     threadId: shell.id,
     title: shell.title,
-    link: formatThreadLink(shell.id, shell.title),
+    link: formatThreadLink({ environmentId, threadId: shell.id }),
     createdBy: shell.createdBy,
     creationSource: shell.creationSource,
     status: shell.activityRunStatus ?? shell.status,
@@ -776,6 +778,7 @@ function listItemFromShell(
 }
 
 function threadDetail(
+  environmentId: EnvironmentId,
   projection: Pick<OrchestrationV2ThreadProjection, "thread" | "runs" | "runtimeRequests">,
   itemCount: number,
   shell: OrchestrationV2ThreadShell,
@@ -787,7 +790,7 @@ function threadDetail(
     threadId: projection.thread.id,
     projectId: projection.thread.projectId,
     title: projection.thread.title,
-    link: formatThreadLink(projection.thread.id, projection.thread.title),
+    link: formatThreadLink({ environmentId, threadId: projection.thread.id }),
     createdBy: projection.thread.createdBy,
     creationSource: projection.thread.creationSource,
     status: active?.status ?? latest?.status ?? "idle",
@@ -1518,7 +1521,10 @@ const make = Effect.gen(function* () {
     const result = {
       taskId: task.id,
       childThreadId: task.childThreadId,
-      link: formatThreadLink(task.childThreadId, childControls.thread.title),
+      link: formatThreadLink({
+        environmentId: scope.environmentId,
+        threadId: task.childThreadId,
+      }),
       childRunId: childRun?.id ?? null,
       childNodeId: task.id,
       status,
@@ -1674,7 +1680,9 @@ const make = Effect.gen(function* () {
     return {
       taskId: task.id,
       childThreadId: null,
-      ...(task.remoteChild === undefined ? {} : { remoteChild: task.remoteChild }),
+      ...(task.remoteChild === undefined
+        ? {}
+        : { remoteChild: task.remoteChild, link: formatThreadLink(task.remoteChild) }),
       childRunId: null,
       childNodeId: task.id,
       status,
@@ -2739,7 +2747,7 @@ const make = Effect.gen(function* () {
                 );
               return {
                 threadId,
-                link: formatThreadLink(threadId, projection.thread.title),
+                link: formatThreadLink({ environmentId: scope.environmentId, threadId }),
                 runId: run?.id ?? null,
                 status: run?.status ?? "idle",
                 title: projection.thread.title,
@@ -2792,7 +2800,7 @@ const make = Effect.gen(function* () {
       return {
         projectId,
         currentThreadId: parent?.thread.id ?? null,
-        threads: page.map((shell) => listItemFromShell(shell, nowMs)),
+        threads: page.map((shell) => listItemFromShell(scope.environmentId, shell, nowMs)),
         nextCursor,
         total: filtered.length,
       } satisfies OrchestratorMcpThreadListResult;
@@ -2872,7 +2880,13 @@ const make = Effect.gen(function* () {
         }
       }
       return {
-        thread: threadDetail(target, timeline.totalItems, shell, yield* Clock.currentTimeMillis),
+        thread: threadDetail(
+          scope.environmentId,
+          target,
+          timeline.totalItems,
+          shell,
+          yield* Clock.currentTimeMillis,
+        ),
         recentRuns: target.runs
           .toSorted((left, right) => right.ordinal - left.ordinal)
           .slice(0, input.runLimit ?? DEFAULT_THREAD_RUN_LIMIT)
@@ -2931,7 +2945,7 @@ const make = Effect.gen(function* () {
         );
       return {
         threadId: input.threadId,
-        link: formatThreadLink(input.threadId, target.thread.title),
+        link: formatThreadLink({ environmentId: scope.environmentId, threadId: input.threadId }),
         messageId,
         runId: result.run.id,
         ...(result.run.delegatedTaskId === undefined ? {} : { taskId: result.run.delegatedTaskId }),