functionalscript · sergey-shandar · Aug 29, 2026 · Aug 29, 2026 · Aug 29, 2026 · Aug 29, 2026
diff --git a/changelog/unreleased/1771.md b/changelog/unreleased/1771.md
@@ -0,0 +1,3 @@
+- `package`: generated `private.d.ts` files are no longer published.
+  `package.json`'s `files` excludes them, dropping 16 files. They were
+  implementation-private by contract, so nothing public depended on them.
diff --git a/fjs/AGENTS.md b/fjs/AGENTS.md
@@ -150,10 +150,10 @@ reaches no reader, the tag buys nothing; `proof.*` is the clear case.
 Which reader differs by file kind, and the tag does not decide it.
 `module.f.mjs` and `types.ts` are public API surface. `private.ts` is not: it
 holds implementation-private types outside the public declaration closure, and
-[`todo/separate-private-types.md`](./todo/separate-private-types.md) plans to
-drop its generated declarations from the package altogether. Its prose is for
-contributors reading the sources, so the tag belongs there — but a public
-documentation build must not be pointed at it.
+its generated declarations are excluded from the package entirely
+([`fsc/README.md`](./fsc/README.md)). Its prose is for contributors reading the
+sources, so the tag belongs there — but a public documentation build must not be
+pointed at it.
 
 Put it in the leading block, followed by one blank line before the first
 source-level import or declaration.

diff --git a/fjs/ci/todo/ci-integration-tests.md b/fjs/ci/todo/ci-integration-tests.md
@@ -36,10 +36,12 @@ Open questions:
       `fjs/ci/common/types.ts`, and cover the new field in the proof. Without
       it the two stages race and the consumer fails at `download-artifact`:
       red for the wrong reason, which is the one failure mode that trains
-      people to re-run a check instead of reading it. This blocks the stage
-      split below and the packed-declaration check in
-      [`../../todo/separate-private-types.md`](../../todo/separate-private-types.md)
-      alike, so it is owned here rather than by either consumer.
+      people to re-run a check instead of reading it. This blocked the stage
+      split below and the packed-declaration check alike, so it is owned here
+      rather than by either consumer. The `needs` field landed in
+      [#1762](https://github.com/functionalscript/functionalscript/pull/1762)
+      and its first consumer in
+      [#1767](https://github.com/functionalscript/functionalscript/pull/1767).
 - [ ] Implement scenario job generation: download artifact, install, run `main`.
 - [ ] Port existing demo/smoke-test steps (`fjs t`, `deno run … t`, `bunx … t`) to the scenario model.
 - [ ] Document the scenario authoring convention.
diff --git a/fjs/ci/todo/f-mjs-package-support.md b/fjs/ci/todo/f-mjs-package-support.md
@@ -166,12 +166,11 @@ exposes private types as `_`-prefixed names in `types.d.ts` and as generated
 `private.d.ts` files. Both are package-private by contract, not public API:
 clean-consumer tests must exercise documented public types and must not turn
 `_`-prefixed declaration artifacts into supported API merely because TypeScript
-emitted them. Unshipping generated `private.d.ts` is the second stage of
-[`fjs/todo/separate-private-types.md`](../../todo/separate-private-types.md),
-by a `!**/private.d.ts` negation in `package.json`'s `files` — an exclusion at
-pack time, with `prepack` unchanged and the working tree left alone. An earlier
-draft of that design deleted the files instead; do not reintroduce a deletion
-step. Once it lands, `private.d.ts` is no longer among the package-private
+emitted them. Generated `private.d.ts` is no longer shipped: `package.json`'s
+`files` carries a `!**/private.d.ts` negation — an exclusion at pack time, with
+`prepack` unchanged and the working tree left alone. An earlier design draft
+deleted the files instead; do not reintroduce a deletion step. So `private.d.ts`
+is no longer among the package-private
 artifacts above — what remains is the `_`-prefixed names that still ship by
 design: `_` types emitted into `types.d.ts` and exported `_` constants emitted
 into `module.d.mts`. The leak-tolerance contract narrows to those, and stays
@@ -247,8 +246,18 @@ emission, `npm pack`, and a clean consumer.
           in particular **not** this fixture. A hand-written import list would
           name the fixture, so a violation placed here fails under a fixed list
           too and proves nothing about enumeration. Measured end to end with
-          `fjs/emergent_testing` in
-          [`../../todo/separate-private-types.md`](../../todo/separate-private-types.md).
+          `fjs/emergent_testing`, which had no `private.ts`: given one, plus an
+          exported binding whose signature names it, the job exits 2 with
+          `TS2307` on the packed declaration.
+
+          The same violation with the `files` negation dropped is **green**,
+          because the private declaration then ships and the reference
+          resolves. So this job does not detect a dropped negation, and nothing
+          else does either: an assertion over the packed listing was written for
+          that and removed as not worth its complexity — what it caught was
+          declaration noise in the tarball, which the `_` contract already
+          tolerates, not a broken package. The negation is one line in
+          `package.json` and losing it is a visible diff in review.
       Scope: the fixture exercises the
       supported, fully erased `import type` form only. The forbidden inline `import { type X }` /
       `import * as` / side-effect forms are a documented one-time measurement
@@ -330,9 +339,11 @@ emission, `npm pack`, and a clean consumer.
         typescript` lets the registry change the verdict with no repository
         change. The version is readable without a checkout: `npm pack` keeps
         `devDependencies` in the packed `package.json`.
-      The private-declaration assertion this job carries for
-      [`../../todo/separate-private-types.md`](../../todo/separate-private-types.md)
-      is a condition on it, specified there; the job itself belongs here.
+      The private-declaration assertion this job carries is a condition on it:
+      every packed declaration is type-checked from the installed artifact, so a
+      public declaration that came to depend on an unshipped private module is a
+      red build. Landed in
+      [#1767](https://github.com/functionalscript/functionalscript/pull/1767).
 - [x] Update `AGENTS.md` to the asymmetric `.f.ts` / `.f.mjs` migration policy.
 - [x] Decide, based on the fixture, whether the second TypeScript runtime-emission
       pass can ever be removed while authored `types.ts` files remain, or whether
@@ -398,9 +409,9 @@ not, and the pipeline is simplified accordingly.
   two-pass `prepack`.
 - [`todo/migrate-typescript-to-mjs.md`](../../../todo/migrate-typescript-to-mjs.md)
   — repository-wide stage-1 implementation source migration.
-- [`fjs/todo/separate-private-types.md`](../../todo/separate-private-types.md)
-  — private-type placement rules and the packaging stage that unships
-  generated private declarations.
+- [`fjs/AGENTS.md`](../../AGENTS.md) §3.2 — private-type placement rules;
+  [`fjs/fsc/README.md`](../../fsc/README.md) — the `_` contract and why
+  generated private declarations are not packaged.
 - [microsoft/TypeScript#46407](https://github.com/microsoft/TypeScript/issues/46407)
   — upstream JSDoc typedef stripping limitation; no longer a blocker here, since
   no authored `.mjs` declares a file-scope typedef to strip.

diff --git a/fjs/fsc/README.md b/fjs/fsc/README.md
@@ -155,10 +155,8 @@ types — function-local in a proof.
 Private types and private runtime constants keep a leading `_`, even when
 linkage requires an export. The underscore is an API contract, not
 declaration-level visibility: generated `.d.ts` / `.d.mts` may still contain
-`export type _Type = number` (and, until the packaging stage of
-[`../todo/separate-private-types.md`](../todo/separate-private-types.md) lands,
-a generated `private.d.ts` still ships), but names that begin with `_` are
-private FunctionalScript implementation details. Consumers must not rely on
+`export type _Type = number`, but names that begin with `_` are private
+FunctionalScript implementation details. Consumers must not rely on
 those names directly, so renaming or removing a `_`-prefixed name is not a
 breaking change solely because TypeScript emitted it. The public contract still
 governs transitive effects: if a public type depends on `_Type`, changing
@@ -199,11 +197,22 @@ module's public vocabulary may be published under an ordinary name even though
 its TypeScript alias was module-private, and a former export may become `_`
 when it only ever described an implementation detail.
 
-Removing shipped private declaration artifacts (`private.d.ts`) from the
-package is the second stage of
-[`../todo/separate-private-types.md`](../todo/separate-private-types.md); the
-`_` contract itself is permanent, since `_` helpers in `types.ts` and exported
-`_` constants keep shipping in emitted declarations regardless.
+No generated `private.d.ts` ships: `package.json`'s `files` excludes them with
+a `!**/private.d.ts` negation.
+
+What CI checks is the consequence, not the exclusion. Every declaration the
+package does carry is type-checked as an outside consumer installs it, so a
+public declaration that came to depend on a private module is a red build
+rather than a broken package. Losing the negation itself is *not* caught: the
+private declarations come back, every reference to them resolves, and that job
+stays green. It is one line, and losing it is a visible diff in review — see
+[`../ci/todo/f-mjs-package-support.md`](../ci/todo/f-mjs-package-support.md)
+for why an assertion over the packed listing was written for that and then
+removed.
+
+The `_` contract is permanent and independent of that. `_` helpers retained in
+`types.ts` by the public declaration closure, and exported `_` constants, keep
+shipping in emitted declarations; they are still not API.
 
 When the last authored implementation/proof `.ts` / `.f.ts` file is gone,
 authored `types.ts` files may remain. The TypeScript runtime-emission pass is