# UploadInputV3 Premature Completion on HTTP 202 Fix Plan

Created: 2026-04-23
Author: smarcet@gmail.com
Status: VERIFIED
Approved: Yes
Iterations: 0
Worktree: No
Type: Bugfix

## Summary

**Symptom:** After uploading a file via UploadInputV3 that triggers HTTP 202 (async server processing), the file immediately shows as "Complete" instead of waiting for polling to confirm the server has finished processing.
**Trigger:** Upload a file via UploadInputV3. Server returns HTTP 202 with `file_id`. Dropzone's `success` event fires immediately (before polling starts or completes), and V3's `handleFileCompleted` marks the file as `complete: true`.
**Root Cause:** `src/components/inputs/upload-input-v3/index.js:153` — `handleFileCompleted()` unconditionally marks the file as `complete: true` when Dropzone's `success` event fires, without checking `file._asyncProcessing`. For non-chunked 202 uploads, `_finished()` is called directly by Dropzone (`dropzone.js:2707`), bypassing the `chunksUploaded` override that defers completion for chunked uploads.

**Secondary issue:** `wrappedOnUploadComplete` at line 190 is a passthrough — it doesn't mark uploading files as complete. When polling finishes, `onUploadComplete` fires but the `uploadingFiles` entry isn't cleaned up because `complete` was never set (if the guard blocks `handleFileCompleted`).

## Investigation

- **V3-specific bug.** V2 has zero handling for `success`/`onFileCompleted`/`complete` — it renders only from the `value` prop, which is updated after `onUploadComplete` (correctly waits for polling in the 202 case).
- **Flow for non-chunked 202:** `xhr.onload` → `file._asyncProcessing = true` → `dropzoneOnLoad(e)` → `_finishedUploading` → `!chunked` → `_finished(files, response, e)` → emits `success` → DropzoneV3 `success` handler → `onFileCompleted` → `handleFileCompleted` marks `complete: true` → file shows "Complete" immediately. Polling starts AFTER `dropzoneOnLoad` returns, but the file already appears done.
- **Chunking decision:** `file.upload.chunked = options.chunking && (options.forceChunking || file.size > options.chunkSize)`. Config sets `chunking: true` but not `forceChunking` (default `false`), and `chunkSize` defaults to 2MB. Files ≤ 2MB are uploaded as non-chunked, bypassing the `chunksUploaded` override entirely.
- **`chunksUploaded` override** at `dropzone/index.js:164` correctly defers `done()` for chunked 202 uploads, but is never called for non-chunked uploads.
- **`wrappedOnUploadComplete`** at `upload-input-v3/index.js:190` just passes through to the parent — it doesn't update `uploadingFiles` state at all.

## Behavior Contract

**Given:** UploadInputV3 with a file upload that returns HTTP 202 (async processing), where `file._asyncProcessing` is set to `true` on the Dropzone file object
**When:** Dropzone's `success` event fires (immediately after `_finishedUploading` calls `_finished` for non-chunked uploads, or via `chunksUploaded` for chunked uploads)
**Currently (bug):** `handleFileCompleted` marks the file as `complete: true` immediately, showing "Complete" in the UI before polling confirms server processing is done
**Expected (fix):** When `file._asyncProcessing` is true, `handleFileCompleted` does NOT mark the file as complete. The file stays in "Loading" state. When polling finishes and `onUploadComplete` fires (via `wrappedOnUploadComplete`), uploading files are marked complete, enabling the existing useEffect cleanup to remove them when `value` updates.
**Anti-regression:** Synchronous uploads (HTTP 200) must still mark files as "Complete" immediately via `handleFileCompleted`. File deletion, error display, progress tracking, and the existing server-renamed-filename cleanup must remain intact.

## Fix Approach

**Chosen:** Guard in V3 handlers
**Why:** The `_asyncProcessing` flag is already set on the Dropzone file object before `success` fires. V3 just needs to check it in `handleFileCompleted` and mark files complete in `wrappedOnUploadComplete`. No changes to DropzoneJS or DropzoneV3 — purely V3 state management.
**Alternatives considered:**
- *Guard in DropzoneV3 success handler* — would work but touches the shared wrapper file used by all upload versions, increasing regression surface.
- *Override _finishedUploading in DropzoneJS* — fixes at the Dropzone level but patches library internals, fragile across Dropzone upgrades.

**Files:**
- `src/components/inputs/upload-input-v3/index.js` (primary fix — handleFileCompleted guard + wrappedOnUploadComplete)
- `src/components/inputs/upload-input-v3/__tests__/upload-input-v3.test.js` (reproducing test)

**Strategy:**
1. In `handleFileCompleted`: check `file._asyncProcessing` — if true, return early (don't mark complete)
2. In `wrappedOnUploadComplete`: before calling the parent callback, mark all uploading files as `complete: true` via `setUploadingFiles`. This ensures cleanup works for both sync (where `handleFileCompleted` already set it) and async (where it was skipped).

**Tests:** Add test to `upload-input-v3.test.js` that simulates: file added → file completed with `_asyncProcessing: true` → verify file still shows "Loading" (not "Complete").

## Verification Scenario

### TS-001: Async Upload Processing State
**Preconditions:** UploadInputV3 with `maxFiles=1`, server configured to return HTTP 202 for uploads

| Step | Action | Expected Result (after fix) |
|------|--------|-----------------------------|
| 1 | Upload a file that triggers HTTP 202 async processing | File shows "Loading" with progress bar, NOT "Complete" |
| 2 | Wait for polling to return `status: 'complete'` and parent to update value | File transitions to "Complete" (from value section), no duplicate entries |

## Progress

- [x] Task 1: Write Reproducing Test (RED)
- [x] Task 2: Implement Fix at Root Cause
- [x] Task 3: Quality Gate
      **Tasks:** 3 | **Done:** 3

## Tasks

### Task 1: Write Reproducing Test (RED)

**Objective:** Encode the Behavior Contract as a failing test BEFORE writing any fix code.
**Files:** `src/components/inputs/upload-input-v3/__tests__/upload-input-v3.test.js`
**Entry point:** `UploadInputV3` component (rendered with mock DropzoneV3)
**Test scenario:**
1. Render UploadInputV3 with `maxFiles=1` and `value=[]`
2. Simulate `onAddedFile({ name: 'video.mp4', size: 5000000 })`
3. Simulate `onFileCompleted({ name: 'video.mp4', size: 5000000, _asyncProcessing: true })`
4. Assert: file still shows "Loading" (not "Complete") — the `_asyncProcessing` flag should prevent marking as complete
**DoD:** Test exists, named `test('does not mark file as complete when _asyncProcessing is true')`, runs, fails because `handleFileCompleted` currently ignores `_asyncProcessing` and marks complete unconditionally.
**Verify:** `npx jest src/components/inputs/upload-input-v3/__tests__/upload-input-v3.test.js --verbose`

### Task 2: Implement Fix at Root Cause

**Objective:** Minimal change to `handleFileCompleted` and `wrappedOnUploadComplete` to prevent premature completion on HTTP 202.
**Files:** `src/components/inputs/upload-input-v3/index.js`
**Strategy:**
1. In `handleFileCompleted` (line 153): add early return when `file._asyncProcessing` is true
2. In `wrappedOnUploadComplete` (line 190): add `setUploadingFiles(prev => prev.map(f => ({ ...f, complete: true })))` before calling the parent callback, so all uploading files are marked complete when the server confirms processing is done
**DoD:** Reproducing test PASSES. Full test suite PASSES. Diff touches root-cause file only.
**Verify:** `npx jest --verbose`

### Task 3: Quality Gate

**Objective:** Full suite re-run, build clean.
**DoD:** Full suite green, build succeeds, no performance regressions.
**Verify:** `npx jest --verbose && npm run build-dev`