bug(plans): create-plan reported no success/error feedback (QA standard user) — verify vs deploy lag #949

Summary

QA (standard-user session) reported that creating a Purchase Plan produces no result and no error/success feedback. Covers two QA sheet rows with the same root cause.

Steps / Expected / Actual

Row 547 — Plan from Opportunities

• Action: On Opportunities, select a commitment, click "Plan from 1 selected".
• Expected: Plan is created.
• Actual: Nothing happens; the Create Purchase Plan modal stays open; no success message.

Row 548 — New Plan from Plans page

• Action: On Plans page, click "New Plan", configure details, submit.
• Expected: Plan is created.
• Actual: Same; nothing happens; modal stays open; no success/error feedback.

Investigation against current base (feat/multicloud-web-frontend @ #883)

Read the full create-plan path FE + BE on the current base:

• Frontend savePlan (frontend/src/plans.ts:1099): wraps the create call in try/catch. On success it closes the modal, reloads plans, and shows a Plan created successfully toast. On any error it keeps the modal open and shows a Failed to save plan: <message> toast. showToast is imported and wired.
• apiRequest (frontend/src/api/client.ts:253): on a non-2xx response it parses the JSON body, reads the error field, and throws an Error carrying that message (and structured details).
• Backend createPlan (internal/api/handler_plans.go:65) + handleRequestError (internal/api/handler.go:372): every failure path returns a JSON body {"error": "..."} — NewClientError for 400/401/403/404 and {"error":"Internal server error"} for the generic 500 case.

Permission gate is NOT the cause. createPlan requires create:plans. DefaultUserPermissions() (internal/auth/types.go:466) grants standard users create:plans and update:plans. The Purchaser-group work (#923/#924) only carves execute / approve-any / retry-any on purchases out of the admin wildcard; it does not touch create:plans. So a standard user is authorized to create plans on the current base.

Conclusion: On the current base the create-plan flow is fully wired for feedback. Success shows a toast and closes the modal; any error (including 403 / 400 / 404 / 500) keeps the modal open and shows a toast with the backend message. There is no silent-failure code path. The savePlan error toast has been present since 2026-03-23 (0ca70ef48).

Reproduces for: neither admin nor standard user on the current base — both get explicit toast feedback.

Most likely cause of the QA observation

Deploy lag. #907/#912 (group-only authz) and #924 (Purchaser group) only reached prod in today's deploy; the QA session very likely ran against a frontend bundle and/or backend that predates the wired-up feedback path or hit a transient backend error. The deployed frontend bundle is built and shipped from this branch, so a stale CDN/bundle can present old behavior even after the backend updates.

A related, already-tracked structural defect is #944 (createPlan returns an opaque 500 with no structured log), which has open PR #946 (fix/create-plan-500-observability). That improves backend root-causing but the user-facing feedback is already correct on the current base.

Recommended action

1. Re-test on the current deploy (post today's deploy) as both admin and standard user. Capture the browser Network tab for POST /api/plans (status + response body) and the toast, if any.
2. If the re-test still shows no toast, this becomes a live frontend bug — attach the captured request/response and reopen scope; otherwise close as deploy-lag.
3. Land fix(api/plans): differentiate ErrNotFound->404 + add structured slog on createPlan errors (closes #944) #946 for backend observability so any future 500 is diagnosable from logs.

No deploy-independent code fix is warranted from the current-base reading: the feedback path is correct and standard users are authorized.