functionalscript · sergey-shandar · Aug 12, 2026 · Aug 11, 2026 · Aug 11, 2026 · Aug 11, 2026
diff --git a/AGENTS.md b/AGENTS.md
@@ -168,7 +168,7 @@ TypeScript-to-JavaScript migration:
 
 Renaming an implementation to `.f.mjs` therefore never requires renaming its
 proof in the same change, and never removes it from proof discovery or from Node
-and Deno coverage: `shouldLoad` in [`fjs/dev/module.f.ts`](./fjs/dev/module.f.ts)
+and Deno coverage: `shouldLoad` in [`fjs/dev/module.f.mjs`](./fjs/dev/module.f.mjs)
 matches both authored extensions, and both `npm run cov` and `deno task cov`
 include `module.f.ts` and `module.f.mjs`. Ordinary (non-FunctionalScript) `.mjs`
 files stay opt-in through the `proof.mjs` filename convention. Stage 1 ends with

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -20,6 +20,61 @@ history.
 
 ## Unreleased
 
+- **BREAKING CHANGES:** `fjs/fsc/json.f.ts` and `fjs/fsc/bnf.f.ts` migrate
+  from authored TypeScript to JSDoc-typed JavaScript (`.f.mjs`) — no
+  local types to split, both use only `Rule`/`TerminalRange` from
+  `fjs/bnf/types.ts`. Importers must use the `.f.mjs` specifier
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/media/json/tokenizer` migrates from
+  authored TypeScript (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`),
+  splitting `JsonToken` and the internal `_ScanState`/`_ScanInput`
+  types into a sibling `types.ts` — importers must use the `.f.mjs`
+  specifier for runtime values and the `types.ts` specifier for types.
+  `proof.f.ts` stays TypeScript for now (it depends on
+  `djs/serializer/module.f.ts`, still unmigrated)
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/js/tokenizer/module.f.ts` migrates from
+  authored TypeScript (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`),
+  splitting `StringToken`, `NumberToken`, `BigIntToken`, `ErrorToken`,
+  `WhitespaceToken`, `NewLineToken`, `IdToken`, `CommentToken`,
+  `EofToken`, `JsToken`, `TokenMetadata`, `JsTokenWithMetadata`, and a
+  large set of internal state-machine types into a sibling `types.ts` —
+  importers must use the `.f.mjs` specifier for runtime values and the
+  `types.ts` specifier for types. `proof.f.ts` stays TypeScript for now
+  (it depends on `djs/serializer/module.f.ts`, still unmigrated)
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/emergent_testing/module.f.ts` migrates from
+  authored TypeScript (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`),
+  splitting `TestFn`, `TestEntry`, `TestSet`, `Path`, `Reporter`, and the
+  internal `_TestState`/`_TestAndPath` types into a sibling `types.ts` —
+  importers must use the `.f.mjs` specifier for runtime values and the
+  `types.ts` specifier for types. `proof.f.ts` stays TypeScript for now
+  (it depends on `media/json/module.f.ts`, still unmigrated)
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/cas/cli` migrates from authored TypeScript
+  (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`) — no local types to
+  split. `proof.f.ts` migrates alongside it. Importers must use the
+  `.f.mjs` specifier
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/cas` migrates from authored TypeScript
+  (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`), splitting `Cas`,
+  `FileCas`, and `FileCasOperation` into a sibling `types.ts` —
+  importers must use the `.f.mjs` specifier for runtime values and the
+  `types.ts` specifier for types. `proof.f.ts` migrates alongside it
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/dev` migrates from authored TypeScript
+  (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`), splitting `Module`,
+  `ModuleMap`, and `LoadModuleOperations` into a sibling `types.ts` —
+  importers must use the `.f.mjs` specifier for runtime values and the
+  `types.ts` specifier for types. `proof.f.ts` migrates alongside it
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
+- **BREAKING CHANGES:** `fjs/effects/node/virtual` migrates from authored
+  TypeScript (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`), splitting
+  `Dir`, `State`, and `JsModule` into a sibling `types.ts`, and narrowing
+  the previously-exported `Entity` to the internal `_Entity` — importers
+  must use the `.f.mjs` specifier for runtime values and the `types.ts`
+  specifier for types. `proof.f.ts` migrates alongside it
+  [#1494](https://github.com/functionalscript/functionalscript/pull/1494)
 - **BREAKING CHANGES:** `fjs/media/type` migrates from authored
   TypeScript (`.f.ts`) to JSDoc-typed JavaScript (`.f.mjs`), splitting
   `DetectState`, `DetectMeta`, and the internal `_Signature`/`_MagicState`/

diff --git a/fjs/bnf/todo/new-parser.md b/fjs/bnf/todo/new-parser.md
@@ -117,7 +117,7 @@ position in a file. Errors instead use metadata:
 
 For matched spans, every ordinary matched symbol arrives with
 `DjsTokenWithMetadata`, so a rule's span has a first and last token and each
-`TokenMetadata` (`{ path, line, column }`, `fjs/js/tokenizer/module.f.ts:158`)
+`TokenMetadata` (`{ path, line, column }`, `fjs/js/tokenizer/types.ts:99-103`)
 gives a real position. `ParseError` (`{ message, metadata: TokenMetadata | null }`,
 `fjs/djs/parser/module.f.ts:16`) widens from a single point to the required range
 where applicable.

diff --git a/fjs/cas/README.md b/fjs/cas/README.md
@@ -1,7 +1,7 @@
 # CAS
 
 Content-addressable storage: blobs on disk, addressed by content hash
-([fjs/cas/module.f.ts](module.f.ts)). The store is type-agnostic — it keeps
+([fjs/cas/module.f.mjs](module.f.mjs)). The store is type-agnostic — it keeps
 raw bytes only, sharded by cBase32 hash under `~/.cas/` — and never records a
 mutable pointer or a per-blob type tag; both are recovered at the edges that
 need them.
@@ -10,7 +10,7 @@ need them.
   media-type detection: `cas_add` / `cas_get` / `cas_list` plus
   [fjs/cas/evo](evo/)'s `evo_list` / `evo_head` / `evo_revision` / `evo_add`,
   all served from one process.
-- [`cas` CLI](cli/module.f.ts) — direct filesystem access for content larger
+- [`cas` CLI](cli/module.f.mjs) — direct filesystem access for content larger
   than the MCP inline-content cap.
 - [fjs/cas/evo](evo/) — the Evo API: subjects and revision heads
   ([vnd.fjs.revision](../media/revision/)) cached in memory over this

diff --git a/fjs/cas/cli/module.f.ts → fjs/cas/cli/module.f.mjs b/fjs/cas/cli/module.f.ts → fjs/cas/cli/module.f.mjs
@@ -3,17 +3,20 @@
  *
  * @module
  */
+
 import { sha256 } from '../../crypto/sha2/module.f.mjs'
 import { cBase32ToVec, vecToCBase32 } from '../../basen/cbase32/module.f.mjs'
 import { forEachStep, pure, step } from '../../effects/module.f.mjs'
 import { errorExit, log, writeFromStream } from '../../effects/node/module.f.mjs'
-import type { All, Read, Write, WriteFile } from '../../effects/node/types.ts'
+/** @import { All, Read, Write, WriteFile } from '../../effects/node/types.ts' */
 import { dispatch } from '../../cli/module.f.mjs'
-import type { Commands } from '../../cli/types.ts'
-import type { MemOp } from '../../effects/memory/types.ts'
-import { casAddFile, fileCas, type FileCasOperation } from '../module.f.ts'
+/** @import { Commands } from '../../cli/types.ts' */
+/** @import { MemOp } from '../../effects/memory/types.ts' */
+import { casAddFile, fileCas } from '../module.f.mjs'
+/** @import { FileCasOperation } from '../types.ts' */
 
-export const commands: Commands<FileCasOperation | WriteFile | Write | All | MemOp | Read> = [
+/** @type {Commands<FileCasOperation | WriteFile | Write | All | MemOp | Read>} */
+export const commands = [
     {
         names: ['add'],
         description: 'Store file content and print its hash',

diff --git a/fjs/cas/cli/proof.f.ts → fjs/cas/cli/proof.f.mjs b/fjs/cas/cli/proof.f.ts → fjs/cas/cli/proof.f.mjs
@@ -1,13 +1,14 @@
-import { commands } from './module.f.ts'
+import { commands } from './module.f.mjs'
 import { computeSync, sha256 } from '../../crypto/sha2/module.f.mjs'
 import { maxLength, vec, vec8 } from '../../types/bit_vec/module.f.mjs'
-import { defaultNodeProgramOptions, emptyState, virtual } from '../../effects/node/virtual/module.f.ts'
-import type { NodeProgramOptions } from '../../effects/node/types.ts'
+import { defaultNodeProgramOptions, emptyState, virtual } from '../../effects/node/virtual/module.f.mjs'
+/** @import { NodeProgramOptions } from '../../effects/node/types.ts' */
 import { dispatch } from '../../cli/module.f.mjs'
 import { vecToCBase32 } from '../../basen/cbase32/module.f.mjs'
 import { assert, assertEq } from '../../asserts/module.f.mjs'
 
-const makeOptions = (args: readonly string[]): NodeProgramOptions =>
+/** @type {(args: readonly string[]) => NodeProgramOptions} */
+const makeOptions = args =>
     ({ ...defaultNodeProgramOptions, args })
 
 const main = dispatch(commands)

diff --git a/fjs/cas/evo/module.f.ts b/fjs/cas/evo/module.f.ts
@@ -47,7 +47,8 @@ import type { Effect, Operation } from '../../effects/types.ts'
 import { eff } from '../../effects/eff/module.f.mjs'
 import { create, read, write } from '../../effects/memory/module.f.mjs'
 import type { Key, MemOp } from '../../effects/memory/types.ts'
-import { collectRead, type Cas } from '../module.f.ts'
+import { collectRead } from '../module.f.mjs'
+import type { Cas } from '../types.ts'
 import { cBase32ToVec, vecToCBase32 } from '../../basen/cbase32/module.f.mjs'
 import { fromVec } from '../../text/utf8/module.f.mjs'
 import { tryUtf8 } from '../../text/module.f.mjs'

diff --git a/fjs/cas/evo/proof.f.ts b/fjs/cas/evo/proof.f.ts
@@ -1,8 +1,9 @@
 import { assert, assertEq } from '../../asserts/module.f.mjs'
 import { pure } from '../../effects/module.f.mjs'
-import { fileCas, type Cas } from '../module.f.ts'
+import { fileCas } from '../module.f.mjs'
+import type { Cas } from '../types.ts'
 import { sha256 } from '../../crypto/sha2/module.f.mjs'
-import { emptyState, virtual } from '../../effects/node/virtual/module.f.ts'
+import { emptyState, virtual } from '../../effects/node/virtual/module.f.mjs'
 import type { Vec } from '../../types/bit_vec/types.ts'
 import { vec, vec8 } from '../../types/bit_vec/module.f.mjs'
 import { cBase32ToVec, vecToCBase32 } from '../../basen/cbase32/module.f.mjs'