Remove std::process::Command invocation of scripts/new-atom.sh from
kei-forge. Templating moves to pure Rust — eliminates the
sed-metacharacter injection class structurally, on top of the
description whitelist that E2 added as defence-in-depth.
src/generate.rs split into 4 Cubes (Constructor Pattern):
- generate/placeholders.rs — 6-token substitution, longer-first ordering
- generate/paths.rs — TargetPaths::resolve + assert_none_exist
- generate/rollback.rs — Drop-based atomic rollback (Rust idiom for
shell `trap ERR`)
- generate/atom_tests.rs — 5 tempdir integration tests
generate.rs dropped from 295 → 159 LOC as orchestration thin wrapper.
Behavioural parity with scripts/new-atom.sh maintained: same 6 tokens,
same order, refuse-overwrite, atomic rollback, same file-list
ordering. scripts/new-atom.sh untouched on disk (still usable as
standalone CLI).
Cargo.toml: removed mock-generate feature flag (no longer needed —
pure-Rust tests use tempfile::TempDir), added tempfile dev-dep.
Tests: 44/44 (was 29 with mock-generate; +15 new pure-Rust unit tests
across placeholders/paths/rollback/atom_tests).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>