## Problem
Two v0.5.6-only regressions were introduced by #4614 (the first enforced
Tauri CSP):
1. **Tab-complete caret regression** — after tab-completing an @mention,
#channel, or :emoji: shortcode, the cursor landed inside the inserted
text instead of after the trailing space. TipTap inserts the correct
text including the trailing space, but without its base stylesheet
(`.ProseMirror { white-space: break-spaces }`) the trailing space
collapses visually and the caret appears mid-name.
2. **Emoji picker unstyled** — the emoji-mart picker rendered as a giant
unstyled layout (oversized search SVG, collapsed grid) because
emoji-mart's shadow-root stylesheet injection was also blocked.
Both symptoms have the same root cause.
## Root Cause
Tauri's build-time asset processor scans `index.html` for inline
`<style>` elements, injects a nonce token, and adds the corresponding
`'nonce-…'` source to `style-src` at runtime. Per the CSP spec, **once a
nonce is present in a directive, the browser ignores `'unsafe-inline'`
for that directive**.
`index.html` contained an inline `<style>` with the boot background
color. When Tauri nonced it and injected `'nonce-…'` into `style-src`,
the intended `style-src 'self' 'unsafe-inline'` became effectively
`style-src 'self' 'nonce-…'` — blocking any runtime stylesheet injection
not covered by a matching nonce:
- TipTap's `injectCSS()` → `createStyleTag()` injecting `.ProseMirror {
white-space: break-spaces; … }`
- emoji-mart's shadow-root `document.createElement('style')` injection
(Inline scripts follow a separate path — they are SHA-256 hashed, not
nonced.)
This only reproduces in packaged builds (where Tauri's custom protocol
serves the HTML and enforces the policy). `tauri dev` loads from the
Vite dev server and is not affected.
## Fix
Move `html { background-color: #000; }` from an inline `<style>` in
`index.html` to `desktop/public/boot.css`, linked via `<link
rel="stylesheet">`. A linked stylesheet is not subject to Tauri's nonce
injection, so `'unsafe-inline'` in `style-src` applies as declared.
The `<link>` is render-blocking (same as the inline style was), so
boot-flash behaviour is identical.
**The production CSP string is unchanged.** This fix makes the policy
apply as intended — no security properties are altered. Will's follow-up
with the security team (Jordan Mecom / Eli Foster, authors of #4614) is
noted for post-ship.
A Tauri-faithful CSP harness for the Vite dev path (so this class of
regression is visible before a packaged build) is tracked as a separate
follow-up.
## Files Changed
- `desktop/index.html` — replace inline `<style>` with `<link
rel="stylesheet" href="/boot.css" />`
- `desktop/public/boot.css` — new file, the extracted `html {
background-color: #000; }` plus rationale comment
- `desktop/src-tauri/tests/csp.rs` — update comment: nonce for styles,
SHA-256 for the boot script
## Testing
- `just desktop-typecheck` ✅
- `just desktop-test` ✅ (4535/4535)
- `just desktop-tauri-test` ✅ (all Rust tests including `csp.rs`)
- Packaged validation: `pnpm tauri build --debug` completed; compiled
binary bakes `style-src 'self' 'unsafe-inline'` with no nonce source
injected ✅
---------
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>
Co-authored-by: Duncan <dcfd242e557282d7a1e2cf2e6877522682f1e5c6156dc92ca7d90eaedd3b0f95@buzz.block.builderlab.xyz>
This change enables a Tauri content security policy that limits
executable content to the packaged application and does not allow inline
scripts.
Relay, media, asset, and Tauri IPC schemes remain available for desktop
compatibility. The policy contains the impact of a future renderer
injection; it does not itself remove an injection bug.
## Testing
- `git diff --check origin/main...codex/security-desktop-csp`
- Rebased onto `origin/main` at `5c98932`
- Full CI pending
Originating Buzz thread:
`buzz://message?channel=3928fe05-df61-4b5d-b9c7-d623b9b10ea1&id=3c6c02312f763fbe0d2bfc33a6c1a362f91d0354f3d18b039cf7a0558c1439d1`
---------
Signed-off-by: Jordan Mecom <jm@squareup.com>
Signed-off-by: Eli Foster <efoster@squareup.com>
Co-authored-by: Eli Foster <efoster@squareup.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
