writing-user-outputs

# Output System Architecture ## Shell Integration Worktrunk uses split file-based directive passing for shell integration: 1. Shell wrapper creates two temp files via `mktemp` (cd and exec) 2. Shell wrapper sets `WORKTRUNK_DIRECTIVE_CD_FILE` and `WORKTRUNK_DIRECTIVE_EXEC_FILE` 3. wt writes a raw path to the CD file; shell commands to the EXEC file (for `--execute`) 4. Shell wrapper reads the CD file with `cd -- "$(< file)"` (no shell parsing) 5. Shell wrapper sources the EXEC file if non-empty When neither directive env var is set (direct binary call), commands execute directly and shell integration hints are shown. ## Output Functions The output system handles shell integration automatically. Just call output functions — they do the right thing regardless of whether shell integration is active. ```rust // NEVER DO THIS - don't check mode in command code if is_shell_integration_active() { // different behavior } // ALWAYS DO THIS - just call output functions eprintln!("{}", success_message("Created worktree")); output::change_directory(&path)?; // Writes to directive file if set, else no-op ``` **Printing output:** Use `eprintln!` and `println!` from `worktrunk::styling` (re-exported from `anstream` for automatic color support and TTY detection): ```rust use worktrunk::styling::{eprintln, println, stderr}; // Status messages to stderr eprintln!("{}", success_message("Created worktree")); // Primary output to stdout (tables, shell code, pipeable) println!("{}...