fix: use GET_PRIVATE_LINK socket command for Wayland clipboard support

[DeepDiver1975]

Problem

On native Wayland sessions the ownCloud daemon has no compositor surface, so
QClipboard::setText() is silently dropped by the compositor. Copy private link to
clipboard never works on Wayland.

Solution

When the session is Wayland, the extension sends GET_PRIVATE_LINK:<file> to the client
(a new socket command added in owncloud/client) and waits for PRIVATE_LINK:<url>. It
then writes to the clipboard via GTK from within the Nautilus process, which does own an
active Wayland surface.

Falls back to the original COPY_PRIVATE_LINK path on X11 sessions and when the client
version predates the new command (timeout → fall-through).

What changed vs PR #11

• No sqlite3/sync journal access
• No config file parsing
• Extension only uses the public socket API — no client internals

Requires: owncloud/client PR for GET_PRIVATE_LINK command.

Testing

• Ubuntu 24.04 LTS, Nautilus 46, native Wayland (GNOME): right-click synced file →
  "Copy private link to clipboard" → clipboard contains the URL ✓
• X11 session: existing behaviour unchanged ✓
• Old client (no GET_PRIVATE_LINK): times out, falls through to COPY_PRIVATE_LINK ✓

[dj4oC]

Companion to the Dolphin extension's Wayland clipboard fix: on Wayland, context_menu_action intercepts COPY_PRIVATE_LINK, sends GET_PRIVATE_LINK:<file>, polls for up to 0.5s for a PRIVATE_LINK: reply, and writes it to the clipboard via GTK3/GTK4 (versioned correctly), falling back to the original socket command on timeout or GTK failure.

Findings

Memory safety: Python — no manual memory management; the GTK clipboard write is wrapped in a broad try/except, which is appropriate here.

Stability/UX concern: _request_private_link polls synchronously inside context_menu_action, briefly blocking the Nautilus extension's calling thread for up to 0.5s. Same category of concern as the Dolphin companion PR, and the timeout (0.5s here vs. 1s in the Dolphin PR) is inconsistent between the two extensions for what should be the same UX.

Cross-repo dependency risk (blocking): Depends on GET_PRIVATE_LINK, added in owncloud/client PR #12535, which this same automated review flagged with a stability: Block finding (use-after-free risk if the socket disconnects before the async reply arrives). Recommend holding this PR until that's fixed upstream.

Platform API: GTK3/GTK4 dual-path clipboard handling is correctly version-gated.

REUSE: Additive changes to an existing licensed file; no new files.

Verdict

Changes requested (pending the upstream client-side fix)

🤖 Automated review by Claude Code (memory-safety · platform-API · REUSE)

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Generated by Claude Code