# Issue #12 — Path-based command execution

**Status:** open
**Related:** #10 (interactive command execution)

## Problem

Issue #10's parser heuristic detects bare-word commands when an **identifier** at statement position is followed by a non-exception-list token. This covers `ls -la`, `git status`, etc. — but not commands invoked by path, because the first token isn't an identifier:

```
./script/update       -- first token is .
../lua                -- first token is .
/bin/ls               -- first token is /
~/bin/deploy          -- first token is ~
```

In standard Lua, none of these are valid statement starts, so claiming them for shell commands doesn't steal any Lua syntax.

## Proposed heuristic

Add parser rules for path-prefixed commands. When the parser sees one of these tokens at statement position, treat the rest of the line as a shell command:

| First token(s) | Pattern | Example |
|----------------|---------|---------|
| `.` `/` | dot-slash | `./script.sh` |
| `.` `.` `/` | dot-dot-slash | `../other/build` |
| `/` | absolute path | `/bin/ls -la` |
| `~` `/` | home-relative path | `~/bin/deploy` |

### Detection

- `.` at statement position → peek next token:
  - `/` on same line → path command (`./ ...`)
  - `.` on same line → peek again: `/` → path command (`../ ...`)
  - anything else → parse as Lua (`.` could be a concat operator fragment, though this isn't valid at statement start anyway)
- `/` at statement position → path command (not valid Lua statement start)
- `~` at statement position → peek next token:
  - `/` on same line → path command (`~/ ...`)
  - anything else → parse as Lua (`~` is bitwise NOT in Lua 5.4, though `~expr` as a bare statement is already a syntax error)

### Argument capture

Same as issue #10: once detected, extract the raw text of the entire line from the source buffer. Emit bytecode equivalent to `_ = __interactive("raw line text")`.

## Examples

```lua
-- all of these run as shell commands
./configure --prefix=/usr/local
../build/lush test.lua
/usr/bin/env python3 -c "print('hello')"
~/bin/deploy staging

-- check exit code like any other interactive command
./run-tests
if _.code ~= 0 then
  print("tests failed")
end
```

## Non-conflicts with Lua

- `/` at statement start: not valid Lua (`/` is division, needs a left operand)
- `./` at statement start: `.` is concat, `/` is division — `./foo` as Lua would be `. / foo` (concat divided by foo), which needs a left operand. Not valid at statement start.
- `../` at statement start: same reasoning, not valid
- `~/` at statement start: `~` is bitwise NOT, `/` is division — `~/foo` as Lua would be `(~()) / foo`, which isn't valid at statement start as a bare expression statement

## Open questions

- Should `~` without `/` be supported? (e.g., `~user/bin/script` — tilde expansion for other users). Probably not initially.
- Should bare `.` or `..` (without `/`) be treated as commands? In shells, `source` is sometimes aliased to `.`. Probably not — too ambiguous.

## Files touched

| File | Description |
|------|-------------|
| `lparser.c` | Add path-prefix detection alongside the identifier heuristic in statement parsing |