[Feature][P2] Add browser-local QR code reverse decoding

[baixiangcpp]

User signal

A product walkthrough suggested that QR Code Generator should also support reverse parsing/decoding.

Original feedback: 还有二维码这种工具我建议补充逆解析。

Product interpretation

The current QR Code Generator is output-only: text -> QR image. Users reasonably expect a QR utility to also support image -> text, especially when checking an existing QR code, auditing campaign links, or verifying a generated code before sharing it.

Relevant files:

• src/features/tools/qr-code-generator/page.tsx
• src/features/tools/qr-code-generator/manifest.ts
• src/features/tools/qr-code-generator/browser-actions.ts
• translations under src/core/i18n/translations/*.json

Recommended scope

Add a browser-local QR decode path. Options:

1. Add decode mode to existing QR Code Generator and rename/page-copy it as a bidirectional QR utility.
2. Add a separate QR Code Decoder tool and link both tools as related tools.

Minimum useful v1:

• Upload or drag/drop PNG/JPEG/WebP image.
• Decode QR payload locally in the browser.
• Show decoded text, URL classification, and copy action.
• Never upload the image or decoded payload.
• Handle failure cases clearly: no QR found, multiple QR codes not supported, image too large, unsupported format.

Optional later:

• Paste image from clipboard.
• Camera scanning behind explicit user permission.
• Decode multiple QR codes in one image.
• URL safety preview before opening external links.

Privacy/security boundary

• Keep the implementation browser-local.
• Avoid automatic navigation to decoded URLs.
• If using camera in a later version, require explicit user action and document permission behavior.
• If using a decoder dependency, lazy-load it so the QR generator's initial route bundle does not regress.

Acceptance criteria

• Users can upload a QR image and decode its payload without network access.
• Decoded output can be copied.
• Decoded URLs are displayed as text first; opening is explicit.
• Decode failure states are clear and localized.
• The feature is covered by unit tests with fixture images or deterministic decoder mocks.
• Tool manifest, related tools, SEO copy, sitemap/index generation, and all locale catalogs are updated.

[baixiangcpp]

Agent-side expanded audit note: implementation should include dependency and bundle review, not only UI work. Before choosing between a combined QR utility and a separate decoder route, inspect available local decoder options for browser-only operation, package size, worker/lazy-load compatibility, and fixture-testability. Add fixture or mocked decoder tests for: valid QR image, no QR found, unsupported file, oversized file, and decoded URL displayed as text without auto-navigation. Also update the QR manifest/related-tools metadata so the decoder is discoverable from generator flows.

[baixiangcpp]

Visual browser audit update - 2026-07-01

Confirmed on the public QR Code Generator route: the current UI only supports text or URL -> QR image. I did not find an upload, drag/drop, paste-image, camera, or decode panel for QR image -> text.

Suggested product shape after using the page:

• A separate tab or mode switch near the existing content panel would likely work better than hiding decode under settings.
• Keep generation as the default mode, but add Decode image as a visible secondary mode.
• The decode result should be displayed as text with Copy and explicit Open link actions. Do not auto-open decoded URLs.
• Keep camera scanning out of v1 unless permission copy and mobile testing are added. Upload/drag-drop is enough for the first browser-local decoder version.

[baixiangcpp]

Resolved in merged PR #335 by commit 1071878: browser-local QR decoding, retryable lazy loading, localized copy, and round-trip coverage. The final PR CI build (Node 20) and Cloudflare Pages checks passed.