#Options reference

Every molt configuration option, grouped by what it controls, with its type, default, and one-line meaning.

Options are shown by their canonical snake_case name. Every option also accepts the changesets-compatible camelCase spelling as an alias; see The config file. Examples below use [tool.molt] TOML, but each has an exact .molt/config.json equivalent.

#Change detection

A package is considered changed when it has at least one changed file whose package-relative path matches changed_file_patterns. Narrow it to skip noise like docs or tests:

[tool.molt]
changed_file_patterns = ["src/**", "pyproject.toml"]

#Versioning and propagation

update_internal_dependents is molt's promotion of a changesets option that used to live behind the ___experimentalUnsafeOptions_WILL_CHANGE_IN_PATCH wrapper. In molt it is a plain, stable, top-level option. "out-of-range" (the default) only pulls a dependent into the release when the dependency's new version would fall outside the dependent's current pin. "always" releases every internal dependent with at least a patch, even when it is still in range -- useful when you want lockstep movement. See Dependency propagation.

bump_workspace_sources_only is molt's rename of changesets' bumpVersionsWithWorkspaceProtocolOnly (which it still accepts as an alias). The Python analogue of npm's workspace: protocol is a dependency backed by [tool.uv.sources] with workspace = true; when this is on, molt only rewrites the pins of such dependencies and leaves externally-versioned ones untouched.

ignore accepts globs and expands them against your package names at load time. An ignore pattern that matches nothing is a warning, not an error -- molt simply drops it and continues:

[tool.molt]
# Never release the docs site or the internal example apps.
ignore = ["acme-docs", "examples-*"]

#Package grouping

[tool.molt]
fixed  = [["acme-core", "acme-runtime"]]
linked = [["acme-cli", "acme-plugins"]]

Each group is a list of package names (globs are also accepted). The difference between the two -- and why molt keeps both, unlike changesets' near-identical published definitions -- is explained in Linked vs fixed.

#Private packages

Private packages -- apps and internal tools you version but never upload to PyPI -- are versioned by default so their internal dependency pins stay correct. Set private_packages = false to leave them out of versioning entirely:

[tool.molt]
private_packages = false

Molt drops changesets' privatePackages.tag sub-option. It gated whether private packages got a git tag during version -- not an npm dist-tag. Molt decides that with molt git-tag, per run, rather than from config, so the option has nothing left to gate (research README section 4.4).

#Changelog and commit

changelog selects the generator that turns changeset summaries into changelog entries. false disables changelog generation. A bare string names a generator; a [generator, options] two-tuple passes options to it. Generators are resolved as Python entry points (or module:attr references), not shell commands, so third parties can publish generators you install like any package:

[tool.molt]
changelog = ["molt.changelog.github", { repo = "acme/acme" }]

See Changelog plugins for the generator contract and Changelog templates for shaping the output.

commit works the same way: false (default) leaves committing to you; true uses molt's built-in commit generator; a string or tuple selects a custom one.

format exists mainly for parity and taste. Molt emits correct, deterministic Markdown itself -- it does not need a formatter pass to clean up broken blank lines the way changesets does -- so the default is false. Set it to "mdformat" if you want written files normalized by an external formatter. Changesets' JS-specific format values ("auto", "prettier", "oxfmt", "deno", "dprint") are accepted for migration but do not pull in a Node toolchain.

#Snapshots

Snapshots produce throwaway, timestamped builds for testing. Because PyPI versions are immutable and it rejects local-version suffixes, molt's snapshot model is reshaped from changesets': suffixes compose a PEP 440 .devN-style build and snapshots target a separate index by default rather than burning a public version number. The template understands the placeholders {tag}, {commit}, {commit-short}, {timestamp}, and {datetime}:

[tool.molt.snapshot]
prerelease_template = "{tag}.dev{timestamp}"
use_calculated_version = true

See Snapshot releases for the full model and how it differs from changesets.

#Backends (molt-native)

These have no changesets equivalent. They select the pluggable backends that make molt work across Python's fragmented tooling.

ecosystem defaults to "auto", which detects a uv workspace and otherwise treats the root as a single package. Set it to "uv" to pin the backend and skip detection:

[tool.molt]
ecosystem = "uv"

"auto" and "uv" are the only values molt accepts today. Poetry, Hatch, PDM and setuptools are scheduled after the 0.1 release; naming one is an error that says so, rather than a silent fallback that would discover the wrong set of packages. The backend seam exists from day one precisely so adding them is an implementation, not a redesign.

If your repo has no uv workspace, you do not need this option at all — a single-package repo is a first-class case, not a degraded one. Most Python projects are single-package; the ratio is inverted versus JavaScript.

See Ecosystems. forge selects the release-automation backend; GitHub ships first, but the seam exists from day one -- see Forges.

#Dropped from changesets

Molt deliberately does not carry these changesets options, because they encode npm/JavaScript concepts with no Python analogue. Configs that still contain them are accepted (the keys are ignored with a warning), so migration does not break.

The $schema key is not a behavioral option -- it drives editor autocomplete for .molt/config.json and is documented under JSON schema.

#Where to go next

• The config file -- where these options live and how validation reports problems.
• Dependency propagation -- what update_internal_dependencies and update_internal_dependents actually do.
• Linked vs fixed -- choosing between the two grouping options.
• JSON schema -- get these options autocompleted in your editor.