Squire

Squire is a transparent local execution and verification layer for coding

agents. It keeps common repository reads hot and continuously maintains whether

the current declared workspace state is verified.

The agent keeps using ordinary terminal commands. Before Codex starts a local

read-only command, Squire checks current state and either replays a proven mmap

observation or executes a small bounded operation over hash-verified current

file bytes. A valid hit returns the exact stdout, stderr, and exit status.

Every miss follows Codex's original native execution path.

Install

curl -fsSL https://raw.githubusercontent.com/reidgoodbar/squire/main/install.sh | bash

The installer verifies matching Squire and Squire-Codex release archives and

installs the driver, Codex runtime helper, and host-native Squire runtime to

`~/.local/bin`. It does not change Codex authentication or configuration.

Supported hosts are macOS and Linux on `amd64` or `arm64`.

Check the installation:

squire doctor

`doctor` exits nonzero when any required driver, helper, runtime, or ABI

component is missing.

Use

Start from any directory:

squire codex

That is the complete user path. There is no setup command, global shell shim,

prompt change, MCP tool, preload injection, or VM provisioning step. If Codex

moves into a repository later, Squire discovers and prepares that repository

from the command's actual cwd.

`squire-codex` is also installed as a direct convenience command.

Inspect the current repository and runtime:

squire status
squire status --json
squire explain -- git status --short

Continuous Verification

Squire Green runs declared tests, lint, typechecks, and builds natively in the

background after repository edits settle. Each result is bound to the exact

declared input bytes, check configuration, environment, and executable. A

later relevant edit makes that result stale; unrelated edits do not.

# .squire/checks.toml
[[check]]
name = "tests"
command = ["go", "test", "./..."]
inputs = ["**/*.go", "go.mod", "go.sum"]
timeout = "10m"

Repository-provided commands never run silently on first use. Review the file

and trust its exact hash once:

squire green trust
squire verify

Any config change revokes trust. `squire codex` then schedules trusted checks

automatically; no second daemon or warm command is required. See

docs/GREEN.md for configuration and proof semantics.

What It Accelerates

Production lanes are bounded but cover the common read-only command surface:

• Git metadata: supported `git rev-parse` forms and branch discovery.
• Repository reads: supported `git status`, `git ls-files`, and `git diff`

forms, including path-scoped diffs and `git diff --check`, plus bounded

`git log -N --oneline -- ` history.

• File and search reads: bounded `cat`, ordered single- or multi-range `sed -n`,

`head`, `tail`, `nl -ba`, `file`, fixed-string `grep`/`rg`, demand-prepared

bounded repository `rg` searches, and tight `ls` forms.

• Environment discovery: supported version probes, `which`/`command -v`, safe

`printenv`, `whoami`, `id`, `hostname`, and `uname` forms.

• Compositions: complete read-only plans over supported sources and filters,

including pipes, sequences, redirection to `/dev/null`, `head`, `tail`,

bounded `sed -n`, `grep -F`, `wc -l`, and `sort`.

No operation is removed. Builds, tests, edits, installs, mutating Git commands,

expansions, unknown shell syntax, sensitive probes, and unsupported variants

immediately follow Codex's unchanged native path. A safe cold miss does the

same while requesting exact preparation in the background. `rg --files`

remains outside the bounded preparation policy and follows the native path.

Supported commands compile into typed bounded plans rather than exact command

templates. Source proof and execution are separate: one proven file snapshot

can serve different line selections, filters, and compositions without a cache

entry for each command string. The same plan representation is implemented by

the Go engine and native runtime, keeping future read operators additive while

differential tests enforce parity at the ABI boundary.

Why Hits Are Current

Squire caches observations, not authority. A foreground replay either

recomputes the inputs that can affect that command or reuses a cryptographic

fingerprint while a complete `kqueue`/`inotify` guard reports no dependency

change. The prepared epoch must still match. Proof inputs include the normalized

command and cwd, Git refs/index/config and external behavior files, relevant

workspace state, canonical paths, content hashes, command-specific environment

proof, and executable identity. Guard failure always invalidates the resident

proof.

For bounded file reads, an epoch mismatch may instead use the current-file

lane: Squire retains the exact bytes read while computing the foreground

SHA-256 proof and applies only its fixed byte grammar to those bytes. This

requires no rewarm and does not persist the file or result. The cache may still

contain stale records, but they are never replayed after a proof mismatch.

Missing state, corruption, unsupported syntax, an ABI mismatch, or an

unprofitable proof all become native fallback.

The invalidation suite changes file bytes without changing size or mtime,

mutates the Git index and untracked set, changes same-size diffs, edits Git

config, commits, renames branches, changes loose and packed object namespaces,

changes environment inputs, and probes outside-workspace symlinks. Returning

old bytes or an unsafe hit fails the release.

See SQUIRE_CONTRACT.md for the complete invariants.

Current Runtime Check

On July 16, 2026, a 500-command randomized production-ABI run recorded 421

exact hits, 79 safe fallbacks, 468 native comparisons, zero mismatches, and

zero unsafe hits. Hit p50/p95/p99 was `0.315/0.630/0.933ms`; the same commands

ran natively at `8.084/27.692/51.820ms`. A separate 500-query repository-search

differential had 500 exact or order-equivalent hits and zero semantic

mismatches. Bounded path history was 28/28 exact at `0.333ms` p50 and `0.492ms`

p99 versus `20.060ms` native p50. All 2,048 steady calls were exact with

`0.433ms` wall p99. Under eight-way load, CPU p99 was `0.334ms`; scheduler-

contended wall p99 was `3.242ms`.

Fresh live `gpt-5.6-luna` treatments independently replayed 2/3 Express calls

(`66.7%`), 5/5 Flask calls (`100%`), and 4/5 fmt calls (`80%`). Every treatment

passed the `50%` all-terminal-call gate with valid accounting and zero

diagnostic mismatches. These small live samples validate coverage, not causal

whole-task wall time; model trajectories diverged before seeing tool results.

A deterministic 40-pair Codex attribution test held model responses, commands,

workspace, and terminal payloads fixed. Six serial calls fell from `374.876ms`

to `103.600ms`, saving `271.277ms` (`72.4%`, paired 95% interval

`265.630-276.540ms`). Two parallel batches saved `52.6%`. AB and BA orders both

remained positive, while interleaved A/A and B/B intervals included zero.

Full methodology and historical tables: docs/BENCHMARKS.md.

Architecture and backend notes: docs/ADVANCED.md.