fix(ui): stop linking foreign tracker keys as Paperclip issues (#7511)

Fixes #7514 — the prefix-validation piece of the #5456 auto-linker
404-storm umbrella. The remaining pieces (404 retry guard, word-boundary
tightening, comment edit/soft-delete) stay open under #5456.

Part of #5456.
## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Agents and humans cross-reference work in markdown — issue
descriptions, comments, documents — which the UI renders through a
shared `MarkdownBody`
> - That renderer auto-links any `IDENT-123`-shaped token to an internal
`/issues/IDENT-123` link
> - But foreign tracker keys share that exact shape: a Jira `TREE-604`
(or any external `ORG-123`) mentioned in prose becomes a link to a
Paperclip issue that does not exist — it 404s, and the renderer also
fires a wasted issue-fetch for the bogus identifier
> - The set of real issue prefixes is already in the browser: every
company carries an `issuePrefix`, exposed via `CompanyContext`
> - This PR gates bare-token auto-linking to known company prefixes,
leaving explicit `issue://` / `/issues/` references and real markdown
links untouched
> - The benefit is no dead internal links from foreign keys, with no new
query, cache, or server change — and zero regression when prefixes
aren't yet known

## What Changed

- **`ui/src/lib/issue-reference.ts`** — `parseIssueReferenceFromHref`
takes an optional `knownPrefixes` set and rejects a bare `IDENT-123`
token whose prefix isn't in it; threaded through
`remarkLinkIssueReferences(options)` → tree rewrite → text and
inline-code paths. An omitted/empty set keeps the legacy permissive
behavior. Explicit `issue://` scheme and `/issues/` path forms are never
gated.
- **`ui/src/context/CompanyContext.tsx`** — adds `useOptionalCompany()`,
a non-throwing variant of `useCompany()` (returns `null` outside a
provider).
- **`ui/src/components/MarkdownBody.tsx`** — reads company prefixes via
`useOptionalCompany()` and passes them to the linkifier. The
non-throwing read keeps `MarkdownBody` renderable in provider-less
surfaces (e.g. standalone/exported markdown).
- Tests extended in `issue-reference.test.ts` (gating + remark-plugin
cases) and `MarkdownBody.test.tsx` (gating, empty-companies permissive,
explicit-path bypass).

## Verification

- `pnpm --filter @paperclipai/ui exec vitest run
src/lib/issue-reference.test.ts src/components/MarkdownBody.test.tsx` —
green (17 + 40 tests).
- Full UI suite: `pnpm --filter @paperclipai/ui exec vitest run` —
**1161 passed / 183 files**; pre-existing `MarkdownBody` link tests pass
unmodified (they hit the permissive `null`-context path), confirming no
regression.
- `pnpm --filter @paperclipai/ui run typecheck` — clean.
- _Screenshots pending — opening as draft; before/after images to follow
before marking ready._
- Manual (before/after): in an issue description containing both a real
Paperclip identifier and a Jira key — _before_ both render as
`/issues/...` links (the Jira one dead); _after_ only the real
identifier links and the Jira key is plain text.

## Risks

- **Low risk.** No server/API/migration change; pure client rendering
logic.
- A referenced issue whose company isn't in the viewer's `companies`
list stops auto-linking — acceptable, since that internal link wouldn't
resolve for that viewer anyway; explicit `/issues/IDENT` references
still render.
- During initial load (companies not yet fetched) behavior is identical
to today (permissive), so no new flicker.

## Model Used

- **Anthropic Claude Opus 4.8** (`claude-opus-4-8`), 1M-token context,
extended thinking + tool use. Plan authored and implemented with the
model; all decisions reviewed by the human contributor.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [ ] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes (no
doc changes required — behavior gated, no public API/doc surface
affected)
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ui/src/components/MarkdownBody.test.tsx

@@ -2,7 +2,7 @@
 
 import type { ComponentProps, ReactNode } from "react";
 import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
-import { describe, expect, it, vi } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import { renderToStaticMarkup } from "react-dom/server";
 import {
   buildAgentMentionHref,
@@ -34,6 +34,18 @@ vi.mock("../api/issues", () => ({
   issuesApi: mockIssuesApi,
 }));
 
+// Defaults to null (no provider) so the existing suite exercises the permissive
+// path unchanged. Gating tests override the return value per-case.
+const mockUseOptionalCompany = vi.hoisted(() => vi.fn<() => { companies: Array<{ issuePrefix: string }> } | null>(() => null));
+
+vi.mock("../context/CompanyContext", () => ({
+  useOptionalCompany: mockUseOptionalCompany,
+}));
+
+afterEach(() => {
+  mockUseOptionalCompany.mockReturnValue(null);
+});
+
 function renderMarkdown(
   children: string,
   seededIssues: Array<{ identifier: string; status: string; title?: string }> = [],
@@ -486,4 +498,38 @@ describe("MarkdownBody", () => {
     expect(html).toContain("paperclip-markdown-issue-ref");
     expect(html).not.toContain("paperclip-mention-chip--issue");
   });
+
+  it("gates bare-identifier auto-linking to known company prefixes", () => {
+    mockUseOptionalCompany.mockReturnValue({ companies: [{ issuePrefix: "PAP" }] });
+
+    const html = renderMarkdown("Depends on PAP-1271 and blocked by JIRA-2.", [
+      { identifier: "PAP-1271", status: "done" },
+      { identifier: "JIRA-2", status: "done" },
+    ]);
+
+    // Known prefix links; foreign tracker key stays as plain text.
+    expect(html).toContain('href="/issues/PAP-1271"');
+    expect(html).not.toContain('href="/issues/JIRA-2"');
+    expect(html).toContain("blocked by JIRA-2.");
+  });
+
+  it("stays permissive when companies are loaded but the list is empty", () => {
+    mockUseOptionalCompany.mockReturnValue({ companies: [] });
+
+    const html = renderMarkdown("See JIRA-2 for context.", [
+      { identifier: "JIRA-2", status: "done" },
+    ]);
+
+    expect(html).toContain('href="/issues/JIRA-2"');
+  });
+
+  it("never gates explicit internal issue paths, even for unknown prefixes", () => {
+    mockUseOptionalCompany.mockReturnValue({ companies: [{ issuePrefix: "PAP" }] });
+
+    const html = renderMarkdown("See /ACME/issues/ACME-1 for the writeup.", [
+      { identifier: "ACME-1", status: "done" },
+    ]);
+
+    expect(html).toContain('href="/issues/ACME-1"');
+  });
 });

ui/src/components/MarkdownBody.tsx

@@ -6,6 +6,7 @@ import remarkGfm from "remark-gfm";
 import { cn } from "../lib/utils";
 import { Link } from "@/lib/router";
 import { useTheme } from "../context/ThemeContext";
+import { useOptionalCompany } from "../context/CompanyContext";
 import { mentionChipInlineStyle, parseMentionChipHref } from "../lib/mention-chips";
 import { issuesApi } from "../api/issues";
 import { queryKeys } from "../lib/queryKeys";
@@ -570,12 +571,19 @@ export function MarkdownBody({
   onImageClick,
 }: MarkdownBodyProps) {
   const { theme } = useTheme();
+  // Read company prefixes non-throwingly: MarkdownBody renders in surfaces that
+  // may lack a CompanyProvider. A null context (or no companies yet) leaves
+  // knownPrefixes undefined, which keeps issue auto-linking permissive.
+  const company = useOptionalCompany();
+  const knownPrefixes = company?.companies.length
+    ? company.companies.map((c) => c.issuePrefix)
+    : undefined;
   const remarkPlugins: NonNullable<Options["remarkPlugins"]> = [remarkGfm];
   if (enableWikiLinks) {
     remarkPlugins.push(createRemarkWikiLinks({ wikiLinkRoot, resolveWikiLinkHref }));
   }
   if (linkIssueReferences) {
-    remarkPlugins.push(remarkLinkIssueReferences);
+    remarkPlugins.push([remarkLinkIssueReferences, { knownPrefixes }]);
   }
   if (softBreaks) {
     remarkPlugins.push(remarkSoftBreaks);