Test-Driven Debugging

> User: We've got a bug in the workspace members list endpoint.
  Users are seeing duplicate members when they page through results.
  It seems intermittent — happens more when there are members with
  the same role. The endpoint is in
  src/routes/workspaces/members.ts and the query is in
  src/dao/member_dao.ts.

⏺ Agent: Let me look at those files.

⏺ Read(src/routes/workspaces/members.ts)
  ⎿  ...

⏺ Read(src/dao/member_dao.ts)
  ⎿  ...

⏺ Agent: I see the issue — the list query in MemberDAO orders by
  `role` and uses OFFSET/LIMIT pagination. If multiple members share
  the same role, the database doesn't guarantee a stable order
  between them, so rows can shift between pages.

> User: That matches what we're seeing. Can you write an issue to
  reproduce this in tests first? Then fix it. Keep track of a chain
  of issues until we fix the root problem.

⏺ Agent: I'll start with a reproduction test.

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (title: "Reproduce duplicate members pagination bug in tests",
   description: "Members list endpoint returns duplicates when paging
   through results where multiple members share the same role.

   ## Reproduction steps
   - Seed 10+ members with the same role in a workspace
   - Paginate through with page_size=3
   - Collect all returned member IDs across pages
   - Assert no duplicates

   ## Expected
   Test should FAIL — confirming the bug exists before we fix it.

   ## Files
   - src/dao/member_dao.ts (the query)
   - tests/dao/member_dao.test.ts (new test)",
   status: "open",
   priority: 1,
   tags: ["bug", "pagination"])
  ⎿  { "id": "i-2r5t", ... }

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (issue_id: "i-2r5t", status: "in_progress")

⏺ Edit(tests/dao/member_dao.test.ts)
  ⎿  Added test: "should not return duplicate members across pages"

⏺ Bash(npm test -- tests/dao/member_dao.test.ts)
  ⎿  FAIL: expected 0 duplicates, found 3

⏺ plugin:sudocode:sudocode - add_feedback (MCP)
  (to_id: "i-2r5t",
   content: "Reproduction confirmed. Test seeds 12 members all with
   role='viewer', paginates with page_size=3. Found 3 duplicate IDs
   across pages. The ORDER BY role clause has no tiebreaker, so
   Postgres returns rows in arbitrary order within the same role.",
   type: "comment")

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (issue_id: "i-2r5t", status: "closed")

⏺ Agent: Bug reproduced and test is failing as expected. Moving on
  to the fix.

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (title: "Fix unstable sort in member list pagination",
   description: "The member list query in MemberDAO orders by `role`
   only, which produces unstable ordering when multiple members share
   a role. This causes duplicates across OFFSET/LIMIT pages.

   ## Fix
   Add `id` as a secondary sort column to guarantee stable ordering.

   ## Verification
   Reproduction test from [[i-2r5t]] should pass after this fix.

   ## Files
   - src/dao/member_dao.ts",
   status: "open",
   priority: 1,
   tags: ["bug", "pagination"])
  ⎿  { "id": "i-6h3k", ... }

⏺ plugin:sudocode:sudocode - link (MCP)
  (from_id: "i-2r5t", to_id: "i-6h3k", type: "related")

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (issue_id: "i-6h3k", status: "in_progress")

⏺ Edit(src/dao/member_dao.ts)
  ⎿  Changed ORDER BY role to ORDER BY role, id

⏺ Bash(npm test -- tests/dao/member_dao.test.ts)
  ⎿  PASS

⏺ plugin:sudocode:sudocode - add_feedback (MCP)
  (to_id: "i-6h3k",
   content: "Added `id` as tiebreaker to ORDER BY clause. Repro test
   passes now. Change is one line in the listMembers query.",
   type: "comment")

⏺ Agent: Fix is in and the reproduction test passes. While I was
  in there, I noticed something — there's also a cursor-based
  pagination path in the same DAO that has the same problem. Want
  me to handle that too?

> User: Yeah, track it and fix it.

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (title: "Fix unstable sort in cursor-based member pagination",
   description: "Same root cause as [[i-6h3k]] — the cursor-based
   pagination path in MemberDAO.listMembersCursor() also orders by
   `role` without a tiebreaker. The cursor comparison uses `role`
   as the cursor value, which is not unique.

   ## Fix
   - Add `id` to the ORDER BY
   - Update cursor to be a composite of (role, id)
   - Update the WHERE clause to use composite cursor comparison

   ## Files
   - src/dao/member_dao.ts",
   status: "open",
   priority: 1,
   tags: ["bug", "pagination"])
  ⎿  { "id": "i-8m1w", ... }

⏺ plugin:sudocode:sudocode - link (MCP)
  (from_id: "i-6h3k", to_id: "i-8m1w", type: "related")

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (issue_id: "i-8m1w", status: "in_progress")

⏺ Edit(src/dao/member_dao.ts)
  ⎿  Updated listMembersCursor() with composite cursor

⏺ Edit(tests/dao/member_dao.test.ts)
  ⎿  Added test: "cursor pagination should not return duplicates"

⏺ Bash(npm test -- tests/dao/member_dao.test.ts)
  ⎿  PASS (3 tests)

⏺ plugin:sudocode:sudocode - add_feedback (MCP)
  (to_id: "i-8m1w",
   content: "Cursor pagination fixed. Changed cursor from just
   `role` to a composite `role:id` string. The WHERE clause now
   does a tuple comparison: (role, id) > (cursor_role, cursor_id).
   Added a dedicated test that seeds members with identical roles
   and verifies no duplicates across cursor pages.",
   type: "comment")

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (issue_id: "i-6h3k", status: "closed")

⏺ plugin:sudocode:sudocode - upsert_issue (MCP)
  (issue_id: "i-8m1w", status: "closed")

⏺ Agent: All three issues closed:
  - i-2r5t: Reproduced the pagination duplicate bug
  - i-6h3k: Fixed OFFSET/LIMIT pagination sort order
  - i-8m1w: Fixed cursor-based pagination sort order