feat(app): implement Product Scan review flow, dynamic batch expiry picker, custom PDFs, PO relationships, and aligned card layouts

backend/AGENTS.md

@@ -111,8 +111,18 @@ Already done for this repo (this split *is* that adoption, mirroring root's own
 
 Same rule as root AGENTS.md §2a: if scope/acceptance criteria are genuinely ambiguous, ask one question at a time (`AskUserQuestion` in Claude Code) until unambiguous, and record the resolved criteria as a 1-3 line note next to the task entry before writing code. Skip when the task is already unambiguous.
 
+### B2b. TDD Workflow (Test First)
+
+- **Write Tests First**: Before implementing the actual feature code for a task, write automated tests defining the expected behavior.
+- **Iterate Until Green**: Run the tests to confirm they fail, then write the implementation until all tests pass perfectly.
+- **Browser Testing**: If the enhancement involves web UI or visual components, use browser tools (e.g., Chrome) to test the app visually and functionally if necessary.
+
 - Implement the task(s) fully, applying the relevant role(s) from `SKILLS.md` (this dir).
-- On completion: flip status to `[DONE]` in `plans/next-enhancements.md`, document the feature in `docs/feature-list.md` (this dir) under the right section.
+- On completion: 
+  1. Flip status to `[DONE]` in `plans/next-enhancements.md`.
+  2. Document the feature in `docs/feature-list.md` (this dir) under the right section.
+  3. **Create an Iteration Log**: Perform a code review and audit of the tasks just completed. Document this audit in `docs/iteration-log.md` (or append to it) to ensure all functions work perfectly.
+  4. **Update Documentation**: Sync any architecture or workflow changes back to `CLAUDE.md` and `SKILLS.md` to keep the agent instructions current.
 - **Verify build integrity**: QA pass (golden path + edge cases + regression check on adjacent features — see `backend/CLAUDE.md`'s accuracy regression harness for OCR/parser changes specifically) and Hardware/Compatibility pass (cross-platform, GPU/VRAM footprint under Local/on-prem deployment — see Part A above).
 - State which task(s) were completed and the exact route/endpoint/menu path to see the new feature.