[ryanmurf]

Problem

rtk grep accepts grep BRE syntax, where \| is alternation and a bare | is a literal pipe. The pattern is then handed to ripgrep, whose default (Rust-regex) engine uses the opposite convention: | is alternation and \| is a literal pipe.

The previous code translated only \| → |:

let rg_pattern = pattern.replace(r"\|", "|");

That fixed the alternation case but left a bare | to be reinterpreted by rg as alternation. So a user searching for the literal substring a|b:

rtk grep 'a|b'   # wanted: lines containing the literal "a|b"

silently over-matched — rg returned every line containing a OR b. This is the over-broadening filter-corruption class: wrong, broadened search results fed to the model with no indication anything was changed.

Verified against rg 14.1.1:

pattern	grep BRE intent	old rtk → rg	result
a|b	a OR b	a|b (alternation)	correct (3 matches)
a|b (bare pipe)	literal "a|b"	a|b (alternation)	wrong: 3, wanted 1

(The first row is a backslash-pipe b; the second is a bare-pipe b. GitHub table escaping obscures the literal characters — see the tests for unambiguous cases.)

Fix

Replace the naive replace() with translate_bre_pipes(), a single scanning pass that swaps both pipe meanings correctly and respects backslash escaping (\\ stays a literal backslash; other escapes like \. \( pass through verbatim).

Tests

• test_bare_pipe_treated_as_literal — the regression: bare pipe becomes an escaped (literal) pipe for rg
• test_bre_alternation_translated — escaped-pipe alternation still maps to rg alternation
• test_mixed_literal_and_alternation_pipes — both meanings in one pattern, no clobbering
• test_escaped_backslash_before_pipe — escaped backslash before a pipe handled correctly
• test_other_escapes_passthrough — \. \( \) untouched
• test_bare_pipe_does_not_overmatch_via_rg — end-to-end: runs rg on a fixture and asserts the literal-pipe search matches exactly one line, not the broadened set

Full suite green locally: cargo test (1728 passed), cargo fmt --check, cargo clippy --all-targets -- -D unsafe_code.

[github-actions]

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