Three changes in one commit:
1. NEW lib/util/atomic-write.mjs — exports atomicWriteJson(path, obj),
the canonical tmp+rename pattern. Reused by pre-compact-flush.mjs and
(in subsequent steps) by the new session-state writer.
2. NEW tests/lib/atomic-write.test.mjs — 4 unit tests covering
round-trip, no-orphan-tmp, overwrite-atomic, pretty-print formatting.
3. REFACTOR hooks/scripts/pre-compact-flush.mjs — replace the inline
atomicWrite() with the imported atomicWriteJson(). Also fixes a
pre-existing syntax error (leading whitespace + stray --resume token
outside the comment block) that silently broke the hook from v3.1.0
onward — PreCompact runtime is fail-open and swallowed the error.
File reformatted with standard zero-indent JS.
163 → 167 tests, 0 fail.
Step 2 of /ultracontinue v3.3.0 (project 2026-05-01-ultracontinue).
Four-layer security model for ultraexecute-local and headless sessions:
Layer 1 — Plugin hooks: pre-bash-executor.mjs (13 BLOCK + 8 WARN rules
with bash evasion normalization) and pre-write-executor.mjs (8 path guard
rules blocking .git/hooks, .claude/settings, shell configs, .env, SSH/AWS).
Layer 2 — Prompt-level security rules: denylist in ultraexecute-local.md
Sub-step D and session-spec-template.md Security Constraints section.
These are the only rules that work in headless child sessions.
Layer 3 — Pre-execution plan validation: new Phase 2.4 scans all Verify
and Checkpoint commands against denylist before execution begins.
Layer 4 — Replace --dangerously-skip-permissions with scoped
--allowedTools "Read,Write,Edit,Bash,Glob,Grep" --permission-mode
bypassPermissions in ultraexecute-local.md, headless-launch-template.md,
and session-decomposer.md. Blocks Agent, MCP, WebSearch in child sessions.
Also adds Hard Rules 14-16: verify command security check, no writing
outside repository root, no writing to security-sensitive paths.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
