refactor(views): give a project mention the component an issue mention has

`IssueMentionCard` owns "chip inside a link" for issues; the project equivalent
lived inline in the readonly renderer, so nothing named the pairing and nothing
held the rules that come with being a link.

That cost was not hypothetical. Both gaps fixed a commit ago landed on project
mentions alone: `.project-mention` never got the CSS rule cancelling generic
link chrome, and the hover card never learned to skip it. Each was written for
`.issue-mention` at the component that owns it, and project had no such place
for the second half to be written. `ProjectMentionCard` is that place.

No behaviour change: same anchor, same href, same hover affordance, same
accessibility contract that project-mention-a11y.test.tsx pins. The "open in
new tab" preference stays out — it is scoped to issue links, and inheriting it
by symmetry would be inventing product.

Also drops `not-prose` from both cards. It has no definition anywhere in the
repo — Tailwind's typography plugin is not installed, and the class does not
appear in built CSS — so it read as protection that was not there.

The editor's `MentionView` keeps its hand-rolled anchors: it needs a
modifier-click intent hook `AppLink` does not expose, and it does the same for
issues, so the two stay symmetric there too.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/views/issues/components/issue-mention-card.tsx

@@ -27,7 +27,7 @@ export function IssueMentionCard({ issueId, fallbackLabel }: IssueMentionCardPro
       href={p.issueDetail(issueId)}
       target={openInNewTab ? "_blank" : undefined}
       newTabTitle={fallbackLabel}
-      className="issue-mention not-prose align-middle"
+      className="issue-mention align-middle"
     >
       <IssueChip
         issueId={issueId}

packages/views/projects/components/index.ts

@@ -2,4 +2,5 @@ export { ProjectsPage } from "./projects-page";
 export { ProjectDetail } from "./project-detail";
 export { ProjectPicker } from "./project-picker";
 export { ProjectChip } from "./project-chip";
+export { ProjectMentionCard } from "./project-mention-card";
 export { LocalDirectoryHint } from "./local-directory-hint";

packages/views/projects/components/project-mention-card.tsx

@@ -0,0 +1,52 @@
+"use client";
+
+import { AppLink } from "../../navigation";
+import { useWorkspacePaths } from "@multica/core/paths";
+import { ProjectChip } from "./project-chip";
+
+interface ProjectMentionCardProps {
+  projectId: string;
+  /** Fallback text when the project is not resolvable (e.g. its title). */
+  fallbackLabel?: string;
+}
+
+/**
+ * Navigable chip — wraps ProjectChip in an AppLink pointing at the project's
+ * detail page. Counterpart of IssueMentionCard, and deliberately shaped like
+ * it: `ProjectChip` is presentational, so whatever wraps it decides that a
+ * mention is a link, and that decision belongs in one place.
+ *
+ * It was in none until now — the wrapper lived inline in the readonly
+ * renderer — and the cost showed up as gaps that landed on project mentions
+ * alone: `.project-mention` never got the CSS rule cancelling generic link
+ * chrome, and the link hover card never learned to skip it. A named component
+ * is where the next such rule has somewhere obvious to go.
+ *
+ * Rendered as a real anchor: a mention must be reachable by Tab, activatable by
+ * Enter, and expose a URL to copy or open in a new tab. A `<span onClick>`
+ * looks identical and works for a mouse, which is exactly why that regression
+ * is easy to miss (see project-mention-a11y.test.tsx).
+ *
+ * AppLink owns plain-click, modifier-click and the desktop new-tab adapter, so
+ * none of that is reimplemented here. Unlike an issue there is no "open in new
+ * tab" preference to honour — that setting is scoped to issue links.
+ */
+export function ProjectMentionCard({
+  projectId,
+  fallbackLabel,
+}: ProjectMentionCardProps) {
+  const p = useWorkspacePaths();
+  return (
+    <AppLink
+      href={p.projectDetail(projectId)}
+      newTabTitle={fallbackLabel}
+      className="project-mention inline-flex"
+    >
+      <ProjectChip
+        projectId={projectId}
+        fallbackLabel={fallbackLabel}
+        className="cursor-pointer hover:bg-accent transition-colors"
+      />
+    </AppLink>
+  );
+}

packages/views/rich-content/rich-content.tsx

@@ -39,7 +39,7 @@ import remarkMath from "remark-math";
 import rehypeRaw from "rehype-raw";
 import rehypeSanitize from "rehype-sanitize";
 import { cn } from "@multica/ui/lib/utils";
-import { useWorkspacePaths, useWorkspaceSlug } from "@multica/core/paths";
+import { useWorkspaceSlug } from "@multica/core/paths";
 import { useConfigStore } from "@multica/core/config";
 import type { Attachment } from "@multica/core/types";
 import {
@@ -48,10 +48,10 @@ import {
   markdownSanitizeSchema,
   markdownUrlTransform,
 } from "@multica/ui/markdown";
-import { AppLink, useAppOrigin } from "../navigation";
+import { useAppOrigin } from "../navigation";
 import { IssueMentionCard } from "../issues/components/issue-mention-card";
 import { useResolveIssueIdentifier } from "../issues/hooks";
-import { ProjectChip } from "../projects/components/project-chip";
+import { ProjectMentionCard } from "../projects/components/project-mention-card";
 import { useLinkHover, LinkHoverCard } from "../editor/link-hover-card";
 import {
   openLink,
@@ -144,34 +144,15 @@ function IdentifierIssueMentionLink({
 }
 
 /**
- * Project mention chip.
- *
- * Rendered as a real anchor via AppLink, matching IssueMentionCard: a mention is
- * a link, so it must be reachable by Tab and activatable by Enter, and expose a
- * URL to copy / open in a new tab. A `<span onClick>` looks identical and works
- * for a mouse, which is exactly why the regression is easy to miss — the readonly
- * renderer used one, and unifying the surfaces would have propagated it to Chat,
- * which previously had the accessible version.
- *
- * AppLink also owns plain-click, modifier-click and the desktop new-tab adapter,
- * so none of that is reimplemented here. The wrapper only shields surrounding
- * click handlers (e.g. collapsed-comment expanders) from mention clicks.
+ * Project mention chip. Navigation and accessibility are owned by the AppLink
+ * inside ProjectMentionCard; the wrapper only shields surrounding click
+ * handlers (e.g. collapsed-comment expanders) from mention clicks — the same
+ * shape as IssueMentionLink above.
  */
 function ProjectMentionLink({ projectId, label }: { projectId: string; label?: string }) {
-  const p = useWorkspacePaths();
   return (
     <span className="inline align-middle" onClick={(e) => e.stopPropagation()}>
-      <AppLink
-        href={p.projectDetail(projectId)}
-        newTabTitle={label}
-        className="project-mention not-prose inline-flex"
-      >
-        <ProjectChip
-          projectId={projectId}
-          fallbackLabel={label}
-          className="cursor-pointer hover:bg-accent transition-colors"
-        />
-      </AppLink>
+      <ProjectMentionCard projectId={projectId} fallbackLabel={label} />
     </span>
   );
 }