## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work.
> - Issue comments are part of the control-plane audit trail and must
respect the same company and issue authorization boundaries as issue
reads.
> - Mention-scoped commenting gives low-trust agents a narrow way to
reply when an authorized assignee mentions them.
> - The comment list route already enforces issue-read authorization,
but the single-comment read route only checked same-company access
before returning a known comment id.
> - That created a broken object-level authorization gap for
same-company low-trust agents outside the issue boundary.
> - This pull request applies the existing issue-read guard to the
single-comment route before loading the comment.
> - The benefit is consistent comment-read authorization across list and
single-comment endpoints, with regression coverage for the low-trust
boundary.
## Linked Issues or Issue Description
Refs #7389
Bug fix context:
- What happened: `GET /api/issues/:id/comments/:commentId` checked
company access but did not enforce the issue-read authorization boundary
before returning a single comment by known id.
- Expected behavior: single-comment reads should use the same issue-read
boundary as issue thread list reads.
- Steps to reproduce: authenticate as a same-company low-trust agent
outside an issue's readable boundary, then request a known comment id
via the single-comment endpoint.
- Deployment mode: applies to server authorization behavior in
authenticated agent API usage.
## What Changed
- Added `assertIssueReadAllowed` to the single issue-comment read route
before `getComment` is called.
- Added mocked route coverage proving peer agents outside the issue-read
boundary get `403` and the comment is not loaded.
- Added authorization and embedded route coverage for mention-scoped
low-trust comment grants so the intended narrow reply path remains
allowed.
## Verification
- `NODE_ENV=test pnpm exec vitest run
server/src/__tests__/issue-agent-mutation-ownership-routes.test.ts` —
passed, 60 tests.
- `NODE_ENV=test pnpm exec vitest run
server/src/__tests__/authorization-service.test.ts` — passed, 26 tests.
- `NODE_ENV=test pnpm exec vitest run
server/src/__tests__/low-trust-red-team-routes.test.ts` — passed, 8
tests.
- `git diff --check` — passed.
## Risks
Low risk. This reuses the existing issue-read guard for a read endpoint.
The main behavioral shift is that same-company actors who cannot read an
issue can no longer fetch a known comment id from that issue, which is
the intended authorization boundary.
> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.
## Model Used
OpenAI GPT-5 via Codex, with repository tool use and command execution.
Runtime context-window details were not exposed by the environment.
## 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 searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge
Co-authored-by: Paperclip <noreply@paperclip.ing>
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