galaxy/specs/GH408/tech.md

Tech Spec: Support ~ expansion in /open-file slash command

Issue: warpdotdev/warp-external#408

Problem

The /open-file slash command handler does not expand ~ before resolving the file path. The argument is unescaped and then joined directly with the current working directory, so ~/foo.txt becomes /cwd/~/foo.txt. The Cmd-O open file palette already handles this correctly by calling shellexpand::tilde().

Relevant code

• app/src/terminal/input/slash_commands/mod.rs (445-450) — The /open-file (commands::EDIT) handler that parses the path argument and resolves it. This is the code that needs to change.
• app/src/search/command_palette/files/data_source.rs:196 — The Cmd-O palette's tilde expansion: shellexpand::tilde(&query_file_content).into_owned(). This is the pattern to follow.
• crates/warp_util/src/path.rs (149-181) — CleanPathResult::with_line_and_column_number(), which strips line/column suffixes from the path string. Called before path resolution.
• app/src/terminal/input_test.rs (2553-2596) — Existing test test_open_slash_command_clears_buffer_on_success that exercises the /open-file handler with a real file.

Current state

The handler in slash_commands/mod.rs does this sequence:

1. Parses line/column suffix with CleanPathResult::with_line_and_column_number(args.trim())
2. Unescapes shell characters with session.shell_family().unescape(&parsed_path.path)
3. Joins with cwd: current_dir.join(&*unescaped_path)

Step 3 always prepends the working directory. When the path starts with ~, this produces an invalid path. There is no tilde expansion step.

Proposed changes

Single change in app/src/terminal/input/slash_commands/mod.rs

After the unescape step (line 449) and before the current_dir.join() call (line 450), add a tilde expansion step using shellexpand::tilde():

let parsed_path = CleanPathResult::with_line_and_column_number(args.trim());
let unescaped_path = session.shell_family().unescape(&parsed_path.path);
let expanded_path = shellexpand::tilde(&unescaped_path);
let file_path = current_dir.join(&*expanded_path);

This works correctly for all cases because of how PathBuf::join behaves:

• Tilde path (~/foo.txt): shellexpand::tilde converts to /home/user/foo.txt (absolute), and join with an absolute path replaces the base entirely.
• Relative path (foo.txt): shellexpand::tilde is a no-op, and join prepends current_dir as before.
• Absolute path (/etc/hosts): shellexpand::tilde is a no-op, and join replaces the base (existing behavior).

No other files need to change.

End-to-end flow

1. User types /open-file ~/Documents/notes.txt and presses Enter.
2. execute_slash_command is called with argument ~/Documents/notes.txt.
3. CleanPathResult::with_line_and_column_number strips any :line:col suffix → path = ~/Documents/notes.txt.
4. shell_family().unescape() removes shell escape characters → path = ~/Documents/notes.txt (no change unless escaped).
5. New: shellexpand::tilde() expands ~ → path = /home/user/Documents/notes.txt.
6. current_dir.join() sees an absolute path and uses it directly.
7. std::fs::metadata confirms the file exists and it opens in the editor.

Risks and mitigations

Risk: shellexpand::tilde could fail if $HOME is not set. Mitigation: shellexpand::tilde returns the input unchanged when the home directory cannot be determined, so it degrades gracefully to the current (broken) behavior. This matches how other call sites in the codebase use it.

Risk: Interaction with shell-escaped ~ from autosuggestions. Mitigation: The unescape step runs before tilde expansion. If autosuggestion produces \~, it unescapes to ~, then tilde expansion works correctly. If somehow ~ was already escaped to mean a literal ~ directory name, that's an extreme edge case not worth special-casing.

Testing and validation

1. New unit test: Add a #[cfg(feature = "local_fs")] test similar to test_open_slash_command_clears_buffer_on_success that creates a temp file at a known location, simulates /open-file ~/relative-to-home using the temp file's home-relative path, and verifies the buffer clears (indicating success).
2. Manual test: Run Warp, type /open-file ~/.bashrc, confirm it opens.
3. Regression: Existing tests (test_open_slash_command_clears_buffer_on_success, test_open_slash_command_requires_path, etc.) continue to pass.

Follow-ups

• Consider supporting $HOME and other environment variable expansion (via shellexpand::full or shellexpand::env) if users request it.
• Investigate whether the completions/autosuggestions engine should also offer ~-prefixed path completions.