Phase 5.12: Pass the Linux replacement gate and record the Tauri baseline

[danielmrdev]

What to build

Prove the direct replacement works as one coherent Linux application and leave an auditable merge handoff. A maintainer can compare Tauri with the recorded Floem baseline, verify product parity and security, and merge without hidden cleanup work.

Acceptance criteria

• Formatting, Clippy, Rust tests, generated-binding checks, TypeScript typecheck, Vitest, component tests, visual checks, and Linux Tauri smoke tests all pass from the integration worktree.
• Manual Linux checks cover IME, keyboard, focus, titlebar, themes, Typeface loading/offline retry, selector, conflicts, close flush, App scale, localization, Spellcheck, and reduced motion.
• A capability and CSP audit confirms the frontend has no direct filesystem, shell, network, remote-content, or undeclared window authority.
• The Floem benchmark protocol is repeated for Tauri, including complete process-tree RSS/PSS, and differences are recorded without unsupported efficiency claims.
• Current README, PRD, AGENTS, ADR, specification, and changelog text describe Tauri as the sole implementation and preserve macOS/Windows as architectural targets.
• The handoff records validation evidence, remaining cross-platform limitations, the approved main-merge step, and post-merge worktree/branch cleanup commands.

Blocked by

• Phase 5.6: Browse, search, and open Files #42
• Phase 5.8: Deliver verified Typefaces through FontFace #44
• Phase 5.10: Scale the whole app with persisted controls #46
• Phase 5.11: Configure native Spellcheck without autocorrect #47

Workspace

• Mode: integration
• Branch: feat/tauri-2-replatform
• Worktree: /home/daniel/Projects/lettera/.worktrees/feat-tauri-2-replatform
• Integrates into: feat/tauri-2-replatform
• Remote policy: local only — never push
• Completion: validate and commit directly in the integration worktree; no lane branch or worktree cleanup is required

[danielmrdev]

Frozen by the approved UI stack decision gate in #49. Do not implement this direct-migration ticket while the Floem/Tauri bake-off is open. Native dependency #54 records the live gate. After the blind decision, this ticket will be reviewed and respecified only if Tauri wins; if Floem wins, it will be closed as replaced.