README.md

@@ -829,8 +829,9 @@ the output.
 
 Semver tags on `main`, `v0.1.0` first; one version covers the shipped data, the
 library and the CLI, and [`CHANGELOG.md`](CHANGELOG.md) names what each release
-changed. A consumer's data, code and scripts keep working across a minor or a patch:
-a minor only adds, and a major is the only release that changes what exists.
+changed. A consumer's data, code and scripts keep working across a minor or a patch,
+except output pinned to a seed. A minor only adds, and a major is the only release that
+changes what exists.
 
 | Surface | Major | Minor |
 |---------|-------|-------|
@@ -843,9 +844,11 @@ a minor only adds, and a major is the only release that changes what exists.
 A patch changes no row of this table: performance, docs, or a fix inside a promised
 behaviour that adds or removes no value and changes no path, format or spelling.
 
-Any release, a patch too, may change what a seed draws, so pin seeded fixtures to one
-version. An error's wording may
-improve in a minor; the path, rejected spelling and replacement it names may not.
+Any release, a patch too, may change what a seed draws, so regenerate seeded fixtures
+whenever the fejkdata version changes.
+
+An error's wording may improve in a minor; the path, rejected spelling and replacement
+it names may not.
 
 Before `v1.0.0` a minor is the breaking unit: `0.(x+1).0` may carry a major's
 changes, each named in the changelog, and a `0.x.y` patch may not. `v1.0.0` is

cmd/fejkdata/main.go

@@ -48,7 +48,7 @@ array, one JSON object per line, one CSV row (after a header), or one INSERT.
       --list             list the paths the data offers, then exit
       --no-shipped-data  load only the --data-path directories
   -n, --repeat N         render the value N times, 1..1048576 (default 1)
-  -s, --seed N           seed for reproducible output
+  -s, --seed N           seed: the same seed, version and data give identical output
       --separator S      string between repeated values (default newline)
       --table T          the INSERT target for --format sql (default: the path's last segment, or records for an inline template)
       --version          print the version, then exit

fejkdata.go

@@ -57,8 +57,8 @@ type config struct {
 // Option configures a [Generator].
 type Option func(*config)
 
-// WithSeed makes output reproducible: two generators with the same seed and data
-// emit identical sequences.
+// WithSeed makes output reproducible: two generators with the same seed, version and
+// data emit identical sequences.
 func WithSeed(seed uint64) Option {
 	return func(c *config) { c.seed, c.seeded = seed, true }
 }

todo.md

@@ -135,7 +135,7 @@
 
 ### 77. Split the shipped data into Go modules per locale and country, which a library imports by choice, and embed every one in the CLI.
 
-The CLI binary carries every module and may grow to hundreds of MB; a library imports only what it uses, as it imports any dependency, and nothing is fetched at run time. Goal 2 says what ships where. The maintainer decided on 2026-10-04: one module per locale, one per country's `geo/` tree, and one for `misc`. A module registers nothing when imported; the library passes it to `New` as an option, per the technical principles "Compose, do not entangle" and "Explicit over implicit". Still to decide: what a bare `New()` loads; whether a module's data is an `fs.FS` passed to the existing `WithDataFS` or a new option such as `WithData(svse.Data)`; and whether `WithoutShippedData` goes. Before the module API ships, a panel of the README's audience personas tries pulling in data with it.
+The CLI binary carries every module and may grow to hundreds of MB; a library imports only what it uses, as it imports any dependency, and nothing is fetched at run time. Goal 2 says what ships where. The maintainer decided on 2026-10-04: one module per locale, one per country's `geo/` tree, and one for `misc`. A module registers nothing when imported; the code importing it passes it to `New` as an option, per the technical principles "Compose, do not entangle" and "Explicit over implicit". Still to decide: what a bare `New()` loads; whether a module's data is an `fs.FS` passed to the existing `WithDataFS` or a new option such as `WithData(svse.Data)`; and whether `WithoutShippedData` goes. Before the module API ships, a panel of the README's audience personas tries pulling in data with it.
 
 ### 78. Ship 10% of every place's streets, at least 10, and 10% of all US places drawn by population, each place weighted by population.