Phase A: container browser-open script (OSC) (flakes-vzo1)

Phase A of flakes-mqe9 — the universal, detection-free browser-open path.

Set the container’s $BROWSER (and an xdg-open shim, since Claude Code / tools may call xdg-open directly rather than honoring $BROWSER) to a script that writes the authorize URL to the human’s controlling TTY (/dev/tty, falling back to stderr — NOT stdout, which CC may capture) as:

• OSC 52 — copy URL to the system clipboard (rides back through zellij/SSH to the terminal).
• OSC 8 — clickable hyperlink.
• plain-text URL + bell.

Because these are terminal escape sequences on the live PTY, they land on whichever terminal the human is at (host desktop or Windows Terminal via WSL/SSH) with no case detection, and follow zellij detach/reattach. One click to open. This is the baseline that makes both access patterns work immediately.

Tasks

• browser-open script (writeShellApplication): URL from $1 (stdin fallback dropped — could block); OSC 52 + OSC 8 + plain + bell to /dev/tty (fallback stderr), single redirection
• Wired environment.variables.BROWSER → script in mcp-oauth-bridge.nix
• xdg-open shim (lib.hiPrio writeShellScriptBin) → browser-open, in systemPackages
• Verified: nix-build; OSC 52 base64 round-trips to URL + OSC 8 URI + bell (od-level); no-arg/empty-stdin exit 1 no hang; full yolo toplevel evaluates (no collision); reviewed

Summary of Changes

Phase A of the browser-open bridge — universal, detection-free.

Files

• packs/nixos/container/mcp-scripts/browser-open.bash (new): writes the authorize URL to the human’s controlling TTY (/dev/tty, else /dev/stderr — never stdout, which CC captures) as OSC 52 clipboard + OSC 8 hyperlink + plain text + bell, in a single redirection. URL from $1 only.
• packs/nixos/container/mcp-oauth-bridge.nix: builds it via writeShellApplication, sets environment.variables.BROWSER, and installs an xdg-open shim (lib.hiPrio) so tools that call xdg-open directly are also caught.

Verified: nix-build; OSC 52 base64 round-trips to the URL, OSC 8 URI correct, bell present (byte-level); no-arg and empty-stdin exit 1 without hanging; bash -n; full yolo toplevel evaluates (hiPrio resolves any xdg-utils collision). Review subagent confirmed escape-sequence spec-correctness, ST bytes, set -e safety of the sink probe, and URL quoting.

Runtime caveat (documented): OSC 52 clipboard and OSC 8 hyperlink passthrough are best-effort under zellij (version/clipboard-config dependent). The script degrades gracefully — the printed plain-text URL is the guaranteed path. No code change needed.

Note: Phase A makes the URL visible/clickable everywhere but is not zero-click and does not itself deliver the OAuth callback — the callback forwards (host socat / WSL LocalForward) live in flakes-ok62 / flakes-q3l5, and zero-click auto-open is Phase B there.