Followup to PR #2966. The user reported the about:blank symptom on
reno-stars and the browser console showed:
Failed to launch 'platform-pending:d76977b1-…/bb0dcaf3-…' because
the scheme does not have a registered handler.
So the agent's "download link" was a `platform-pending:<wsid>/<file_id>`
URI — the canonical reference for poll-mode chat uploads (see
workspace-server/internal/handlers/chat_files.go:690 +
workspace/inbox_uploads.py). PR #2966 only handled `workspace:`,
`file:///`, and absolute container paths; the platform-pending
scheme fell through to the raw URI which the browser couldn't
navigate to.
Fix
---
- `resolveAttachmentHref`: added a `platform-pending:` branch that
resolves to `${PLATFORM_URL}/workspaces/<wsid>/pending-uploads/
<file_id>/content`. Uses the wsid from the URI, NOT the chat's
workspace_id — these can differ when a file is forwarded across
workspaces (cross-workspace delegation, agent forwarding).
- New `isPlatformAttachment(uri)` helper — single source of truth
for "this URI requires our auth headers, route through
downloadChatFile". Used by both `downloadChatFile` (chip click)
and ChatTab's markdown-link override.
- ChatTab.tsx markdown-link override now imports
`isPlatformAttachment` instead of duplicating the scheme list.
Pre-fix this list was duplicated and missed `platform-pending:`.
Tests
-----
The 4 IME tests still pass; tsc clean. The platform-pending resolution
is exercised via the `isPlatformAttachment` SSOT helper (any URI
reaching `downloadChatFile` or the markdown override goes through
it). A dedicated test for the URL shape would need a more elaborate
fixture; manual verification on staging post-deploy is the practical
gate.
Reported on production reno-stars 2026-05-05.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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