`cabin.lock` Reference

Cabin uses a deterministic on-disk lockfile that records the package versions chosen by the resolver. Artifact fetching reuses the same schema and uses the recorded checksum to verify each fetched source archive in cabin fetch and cabin build.

The lockfile is generated - Cabin owns its content. Tracking it in version control is recommended so collaborators and CI converge on the same resolution and on the same archive bytes.

Workflow

# First resolve: writes cabin.lock next to the root manifest.
cabin resolve --manifest-path app/cabin.toml --index-path index

# Subsequent resolves prefer the locked versions even if newer ones
# exist (as long as constraints still allow them).
cabin resolve --manifest-path app/cabin.toml --index-path index

# Refresh the lockfile to the newest compatible versions.
cabin update --manifest-path app/cabin.toml --index-path index

# Refresh one package.
cabin update --package fmt --manifest-path app/cabin.toml --index-path index

# CI mode: require an up-to-date lockfile, never write.
cabin resolve --locked --manifest-path app/cabin.toml --index-path index

--locked and --frozen both forbid writing cabin.lock. The distinction is intent: --frozen additionally forbids any other state-writing side effect. It must not populate the artifact cache. Already-cached, already-extracted artifacts may be reused.

File location

cabin.lock lives next to the root manifest:

cabin resolve --manifest-path app/cabin.toml writes app/cabin.lock.
For workspace roots the lockfile sits beside the workspace root manifest, not inside any member directory.
The lockfile is not placed inside --build-dir.

Format

# This file is automatically generated by Cabin.
# Do not edit it manually.

version = 1

[[package]]
name = "fmt"
version = "10.2.1"
source = "index"
checksum = "sha256:0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"

[[package]]
name = "spdlog"
version = "1.13.0"
source = "index"
checksum = "sha256:fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210"
dependencies = ["fmt"]

Field	Where	Required	Description
`version`	top level	yes	Schema version. Cabin supports only `1`.
`[[package]]`	repeated	yes per package	One entry per resolved registry package. Sorted alphabetically by name.
`name`	package	yes	Package name.
`version`	package	yes	Resolved SemVer version.
`source`	package	yes	Where the package came from. Cabin supports `"index"` plus local provenance records for patches and vendoring.
`checksum`	package	no	`sha256:<hex>` digest of the source archive’s bytes. In `--locked` mode the resolver fails on lockfile-vs-index disagreement; in `cabin fetch` / `cabin build` the same value is used to verify the archive’s content as it is copied into the cache.
`dependencies`	package	no (only emitted when non-empty)	The package’s transitive dependency names, sorted alphabetically.

Local path packages are deliberately not recorded in cabin.lock; they are resolved structurally on every load by cabin-workspace.

[target.'cfg(...)'.<kind>] predicates are evaluated before resolution against the host platform, so the lockfile records the host-evaluated closure exactly as if the non-matching entries had never been declared. The target field is therefore not stored on locked packages - re-running on a host whose predicates re-evaluate to a different set updates the lockfile via the ordinary cabin update path. See target-dependencies.md.

The format is strict:

the parser uses deny_unknown_fields; a typo or unsupported key is a clear error;
version = 1 is the only accepted schema version;
duplicate [[package]] entries (same name) are rejected;
invalid SemVer in any version field is rejected;
unknown source values are rejected.

The writer guarantees:

a stable header comment;
alphabetical ordering of [[package]] entries by name (then by version);
alphabetical ordering of each entry’s dependencies list;
byte-identical output for the same in-memory Lockfile;
atomic replacement of an existing cabin.lock: the new bytes land in a sibling temporary file and only rename onto the destination after a successful write, so an interrupted run leaves the previous lockfile intact.

`[[patch]]` and `[[source-replacement]]` arrays

When the active local-policy layer (manifest [patch] table plus config patches and source replacements) is non-empty, the lockfile carries deterministic top-level arrays that record exactly the policy applied:

[[patch]]
package = "fmt"
version = "10.2.1"
kind = "path"
provenance = "manifest"
path = "../fmt"

[[source-replacement]]
original = "https://example.com/index"
original-kind = "index-url"
replacement = "../mirror"
replacement-kind = "index-path"
provenance = "user-config"

Both arrays are optional: old lockfiles that omit them parse unchanged, and Cabin only writes them when at least one entry is active. Under --locked, if the recorded arrays differ from the active policy, resolution surfaces a stale-lockfile error (--locked cannot be used because active patch / source-replacement policy differs from <lockfile>). --no-patches empties both arrays for the current invocation.

The patch-state staleness check is independent of whether the resolver itself runs. Even when the active patches cover every versioned dependency (so the resolver has nothing to do and prints (no versioned dependencies)), --locked still compares the recorded arrays against the active policy: adding or removing a patch since the lockfile was written makes the lockfile stale, and --locked will refuse rather than silently succeed. Comparison uses the same canonical (sorted) arrays the renderer emits, so it is deterministic.

Full protocol in patch-overrides.md.

Commands

`cabin resolve`

Default mode. Reads cabin.lock if it exists. Resolves with the locked versions as preferences (newest compatible if the locked version no longer satisfies). Writes the new lockfile if it differs from the existing one.

`cabin resolve --locked`

Reads cabin.lock and requires it to be current:

fails if the lockfile does not exist;
restricts each candidate set during resolution to the locked version, so any deviation surfaces a precise error (missing package, missing version, yanked, constraint violation, checksum mismatch);
never writes the lockfile.

Use this in CI to verify that contributors didn’t forget to commit their lockfile updates.

`cabin resolve --frozen`

Same lockfile-strict semantics as --locked plus a stricter promise: no generated state should be written. For cabin fetch and cabin build, this also means the artifact cache must not be populated - already-cached and already-extracted artifacts may still be reused, but a cache miss in --frozen is a clear error rather than an excuse to copy.

`cabin update`

Re-resolves everything, ignoring the locked map. Writes the new lockfile.

`cabin update --package <name>`

Drops one entry from the locked map and re-resolves with the rest still preferred. Useful for refreshing one dependency without touching the rest of the graph.

--package validates that <name> is a versioned dependency of the root package - otherwise it errors.

Yanked versions

The resolver always excludes yanked candidates in PreferLocked / UpdateAll / UpdatePackage. In Locked mode (--locked / --frozen), if the locked version is yanked, the resolver fails with a clear error so the user is forced to run cabin update.

Pre-release versions

Pre-release versions (1.0.0-alpha, 2.0.0-rc.1, …) are excluded from candidate selection by default, mirroring semver::VersionReq::matches. A pre-release version is admitted only when one of the comparators making up the requirement names the same major.minor.patch with a non-empty pre tag - for example fmt = "=1.0.0-alpha" (singleton opt-in) or fmt = ">=1.0.0-alpha, <1.0.0" (range that explicitly opens the 1.0.0 pre-release window). Wide constraints such as fmt = ">=1.0.0, <2.0.0" never pick a pre-release even if one is the only candidate published in the index. A locked-in pre-release survives a follow-up cabin resolve so existing lockfile pins do not silently churn.

Resolver diagnostics

Dependency resolution failures are rendered through Cabin’s miette-based diagnostics layer. Every variant of ResolveError carries the stable diagnostic code cabin::resolver::error along with per-variant help text. Locked-mode errors remain specific so users can tell whether to update the lockfile, fix constraints, or investigate a checksum mismatch; conflict failures embed a human-readable explanation derived from PubGrub’s reporter output.

Limitations

The following are not part of the current lockfile contract:

network registry access (HTTP / sparse index client)
registry authentication
a registry server
package publishing (cabin package, cabin publish)
OCI / GHCR or other remote-archive transports
a binary artifact cache or remote build cache
alternative source values in cabin.lock such as path or git
locking of local path packages
workspace-level cabin.lock for workspaces without a root [package]
a separate cabin generate-lockfile command (cabin resolve and cabin fetch are the producers)
a public JSON Schema document for cabin.lock

cabin.lock Reference