fix: honor VOICEBOX_DATA_DIR in both the backend and the desktop app

[Lvigentini]

backend/README.md documents VOICEBOX_DATA_DIR alongside --data-dir as a way to override the data directory, but it never worked. Two open issues report this: #981 and #533.

Why it was broken in two places

Backend. config.py only wired up VOICEBOX_MODELS_DIR; the data directory default stayed hardcoded to ./data.

Desktop app. Fixing the backend alone is not enough. The Tauri shell resolved the directory from app.path().app_data_dir() unconditionally and passed it to the sidecar as an explicit --data-dir, which beats the environment variable on the Python side. Both issue reports show it in the log:

Arguments: [...'voicebox-server.exe', '--data-dir',
            'C:\Users\<user>\AppData\Roaming\sh.voicebox.app', ...]

So the variable could only ever reach a bare uvicorn backend.main:app, never the packaged app.

Changes

• backend/config.py — read VOICEBOX_DATA_DIR when computing the default. --data-dir still takes precedence, since it calls set_data_dir() after import. This is also the only override that reaches just dev, which starts uvicorn directly and never parses CLI arguments.
• tauri/src-tauri/src/main.rs — resolve the override before the argument is built. data_dir_str feeds all four sidecar spawn sites, so one change covers the plain, ROCm, CUDA and fallback paths.

Unset, empty and whitespace-only all mean "no override", so a variable cleared to "" falls back to the platform path rather than the process working directory. Surrounding whitespace is trimmed, since variables set through the Windows GUI often carry a trailing space.

The startup log now names which source won, and the create_dir_all failure names the path, so a typo surfaces as an actionable error rather than a silent fallback.

Behaviour note

The Tauri data_dir also anchors backends/rocm, backends/cuda and the backend_override file, so those move under the overridden directory too. That seemed right — the point of the variable is to put app data somewhere else — but flagging it in case you'd rather scope the override more narrowly.

Tests

• backend/tests/test_data_dir_env.py covers the precedence rules on the Python side.
• Four unit tests in main.rs cover the override decision: unset, empty, whitespace-only, verbatim path, and trimming. cargo test --bin voicebox passes.

No UI changes, so no screenshots apply.

Fixes #981
Fixes #533

Also partially addresses #577

#577 asks for the Generated and Captured folder locations to be configurable. Both sit under the data directory, so both move with this change — two of that issue's three asks. What it does not cover is downloading models straight to a chosen location (the issue's first point; VOICEBOX_MODELS_DIR plus the existing migration flow is the current answer), or a folder picker in Settings. Leaving #577 open on that basis rather than claiming it.

Refs #577

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Configure the application’s data directory with the VOICEBOX_DATA_DIR environment variable.
  • Relative paths are resolved consistently, and surrounding whitespace is removed.
  • Explicit data-directory settings continue to take precedence over the environment variable.

• Bug Fixes

  • Improved fallback behavior when the variable is missing, empty, or whitespace-only.

• Tests

  • Added coverage for configuration, path resolution, defaults, trimming, and overrides.

[coderabbitai]

📝 Walkthrough

Walkthrough

VOICEBOX_DATA_DIR now configures the backend and Tauri data directories. Blank values use existing fallbacks. Relative paths resolve to absolute paths. Explicit set_data_dir() values remain authoritative.

Changes

Data directory configuration

Layer / File(s)	Summary
Backend data directory resolution backend/config.py, backend/tests/test_data_dir_env.py	The backend reads and resolves VOICEBOX_DATA_DIR. Tests cover configured, default, empty, relative, module restoration, and explicit set_data_dir() values.
Tauri startup data directory resolution tauri/src-tauri/src/main.rs	Tauri trims valid environment values, ignores blank values, selects the configured or platform app-data directory, reports its source, creates the selected directory, and tests each path form.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• jamiepine/voicebox#987: This PR implements VOICEBOX_DATA_DIR support in backend and Tauri data-directory resolution.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes honor VOICEBOX_DATA_DIR, preserve --data-dir precedence, and address the reported desktop-app failures with tests [#981, #533].
Out of Scope Changes check	✅ Passed	All production and test changes support VOICEBOX_DATA_DIR handling, precedence, path resolution, and the linked desktop-app fixes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: honoring VOICEBOX_DATA_DIR in both the backend and desktop app.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@backend/tests/test_data_dir_env.py`:
- Around line 40-41: Restore the original environment before reloading config in
the fixture teardown, so config is reinitialized without the test’s
VOICEBOX_DATA_DIR value. Update the cleanup around importlib.reload(config),
preserving the existing environment-matching behavior for subsequent tests.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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Reviewing files that changed from the base of the PR and between 51f49de and f287649.

📒 Files selected for processing (2)

• backend/config.py
• backend/tests/test_data_dir_env.py

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@tauri/src-tauri/src/main.rs`:
- Around line 221-225: Update data_dir_override to resolve non-absolute values
against the Tauri process directory before returning them, while preserving
absolute overrides and empty-value handling. Ensure start_server and the
ROCm/CUDA launch paths use this resolved path for directory creation and
--data-dir construction. Add coverage for a relative override asserting the
selected path is absolute and consistent with backend/config.py and
test_data_dir_env.py.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: d23711a5-c42f-42b1-9d67-77d9f335765e

📥 Commits

Reviewing files that changed from the base of the PR and between f287649 and 5eb2481.

📒 Files selected for processing (1)

• tauri/src-tauri/src/main.rs

[Lvigentini]

Verified end to end on Windows 11 against a build from this branch.

Set VOICEBOX_DATA_DIR to an empty C:\Users\psyco\test_folder and launched the built app. Startup log:

=================================================================
Starting voicebox-server sidecar
Data directory: "C:\Users\psyco\test_folder" (from VOICEBOX_DATA_DIR)
Remote mode: false
No ROCm backend found
No CUDA backend found, using bundled CPU binary
Sidecar command created successfully
Spawning bundled CPU server process...

GET /health/filesystem — the exact check from #981, which previously returned AppData paths:

{"healthy": true, "directories": [
  {"path": "C:\Users\psyco\test_folder\generations", "exists": true, "writable": true},
  {"path": "C:\Users\psyco\test_folder\captures",    "exists": true, "writable": true},
  {"path": "C:\Users\psyco\test_folder\profiles",    "exists": true, "writable": true},
  {"path": "C:\Users\psyco\test_folder",              "exists": true, "writable": true}]}

The directory was populated with backends/, captures/, generations/, profiles/ and a fresh 139 KB voicebox.db, and GET /profiles returned 0 — the app came up on an empty database rather than the existing library, which confirms it is genuinely reading from the override and not just logging it. The real data directory was untouched (voicebox.db still 1,839,104 bytes).

Also worth flagging from the same build: just build fails at the very end with

A public key has been found, but no private key.
Make sure to set `TAURI_SIGNING_PRIVATE_KEY` environment variable.
error: recipe `build-tauri` failed

Both installers are produced before that point, so it only affects the updater artifacts — unrelated to this PR, but it means a local just build exits non-zero without that secret.