Merge pull request #2546 from deepseek-harness/fix/publish-deporder

fix(release): order publication by installed dependencies and keep npm's output

.agents/notes/implemented/process/2026-08-10-npm-release-sequences.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/process/2026-08-10-npm-release-sequences.md
-2026-08-10-npm-release-sequences.md: e74a4ac8f2aadd8665ec0db198c6a317a0c201bc
-2026-08-10-npm-release-sequences.zh.md: e152163976f945224f2524fccd7f831ba98e8161
+2026-08-10-npm-release-sequences.md: d8495f158482d5d6e06a1752a096d1e9200b6070
+2026-08-10-npm-release-sequences.zh.md: 24b466f6b7b10d31ac2e025da6e12ec3c91c7548

.agents/notes/implemented/process/2026-08-10-npm-release-sequences.md

@@ -80,6 +80,14 @@ Every reference to a workspace member uses `workspace:^`, so `pnpm pack` substit
 
 `scripts/check-workspace-constraints.ts` requires the protocol, so a new package cannot reintroduce a hand-written range; the invariant-companion rule requires `workspace:^` for `@deepseek-ai/dsh-invariants` for the same reason.
 
+### An optional dependency is never loaded at module scope
+
+A dependency in `optionalDependencies`, or a peer carrying `peerDependenciesMeta.<name>.optional`, may be absent from an installed tree — that absence is the whole promise of "optional". A static import is evaluated when the importing module loads, so one absent package stops being "this capability is unavailable" and becomes a load failure for everything that reaches the importing module. The failure appears only in an installed tree missing that package, and no test here constructs one: a workspace install always has every package, so the unit tests, the snapshots, and the packed-install probe all pass while the published package is broken for the consumer who declined the optional peer.
+
+[`verify-optional-dependency-imports`](../../../../scripts/verify-optional-dependency-imports.ts) closes that hole. It reads each package's own manifest for what that package allows to be absent, then scans the files that ship — `packages/*/*/src/` and `apps/*/src/` — across both compiler faces. `vendor/` is out of scope, as pinned upstream source under the [vendoring policy](../../../../vendor/README.md). Value-versus-type is decided against a bound Program rather than the import syntax, because `verbatimModuleSyntax` is off: the compiler already erases an import whose bindings resolve to types, so `import type {}`, `import {}`, an inline `type` specifier, and a named binding that resolves to a type all emit nothing and are allowed, while a bare import, a value binding, and a star re-export are kept and rejected. Only the type phase erases an import: `import defer` still resolves and links its module, deferring evaluation alone, so the gate counts it as a load.
+
+A violation names the package, the declaration that made it optional, and the way out in order — import it as a type, which is all that declaration merging needs, or restructure so module scope does not need the package. A dynamic `import()` only moves the failure to first use, so it belongs to a caller that genuinely requires the package and handles its absence; reaching for it is a sign the dependency is not optional, and the gate does not offer it as the remedy.
+
 ### Release family objects
 
 The entity in this domain is a **release family**: a set of packages sharing one version baseline and tag naming that publishes as a unit. Adding a family means adding a subclass and a workflow lane, not changing the core.
@@ -88,9 +96,9 @@ The entity in this domain is a **release family**: a set of packages sharing one
 |---|---|
 | `ReleaseFamily` | a family's identity: member discovery, version baseline, tag prefix, packed-payload rule, installed entry |
 | `ReleaseMember` | one publishable package: directory, name, version, manifest |
-| `publishOrder` | topological order over runtime dependencies, ties broken by package name; a cycle is reported rather than resolved arbitrarily |
+| `publishOrder` | topological order over the sections npm installs plus peer declarations, ties broken by package name; a cycle among installed dependencies is reported rather than resolved arbitrarily, and a peer edge no order can honour is dropped and named |
 | `pack` | packs a whole family into one directory and records the upload order |
-| `verify` | the family's version baseline, and — when publishing — that the run comes from that family's tag and its members are publishable |
+| `verify` | the family's version baseline, the publish order it prints in full, and — when publishing — that the run comes from that family's tag and its members are publishable |
 | `verify-packed-install` | installs the tarballs of one or more pack directories into a throwaway consumer and drives the installed executable |
 | `publish` | the three registry states above |
 | `process` / `tarball` | the one home for spawning commands and for reading a packed tarball, including the entry guard that keeps every script importable |

.agents/notes/implemented/process/2026-08-10-npm-release-sequences.zh.md

@@ -80,6 +80,14 @@ registry 的两个行为决定了「怎么尝试一次发布」。写入之间
 
 `scripts/check-workspace-constraints.ts` 要求这个协议，所以新包无法再引入硬写的范围；同理，invariant companion 规则要求 `@deepseek-ai/dsh-invariants` 用 `workspace:^`。
 
+### optional 依赖绝不在模块作用域被加载
+
+`optionalDependencies` 里的依赖，或带 `peerDependenciesMeta.<name>.optional` 的 peer，在安装出来的树里可以不存在——这份「可以不存在」正是 optional 的全部承诺。而静态 import 在引入方模块加载时就求值，于是一个缺失的包不再表现为「这个能力不可用」，而是变成所有能走到该模块的代码的加载失败。这种失败只在「缺了该包的安装树」里出现，而本仓没有任何测试构造这种树：workspace 安装总是把每个包都装上，所以单测、快照、打包安装探针全都会过，而那个拒绝了这个 optional peer 的消费者拿到的却是坏的包。
+
+[`verify-optional-dependency-imports`](../../../../scripts/verify-optional-dependency-imports.ts) 堵掉这个洞。它从每个包自己的 manifest 读取「这个包允许谁缺失」，再扫描会发布出去的文件——`packages/*/*/src/` 与 `apps/*/src/`——且两个编译门面各扫一遍。`vendor/` 不在范围内，那是[受 vendoring 政策管辖](../../../../vendor/README.md)的固定上游源码。值与类型的判定对着绑定好的 Program 做，而不是看 import 写法，因为 `verbatimModuleSyntax` 是关的：编译器本来就会消除绑定解析为类型的 import，所以 `import type {}`、`import {}`、内联 `type` 说明符、以及解析为类型的具名绑定都不产生产物、一律放行，而裸 import、值绑定、星号 re-export 会被保留、一律报错。只有 type 相位会消除 import：`import defer` 仍然解析并链接它的模块，只推迟求值，所以门禁把它算作一次加载。
+
+报错会点名这个包、点名是哪条声明把它标成 optional 的，并按顺序给出出路——把它作为类型引入（声明合并需要的仅此而已），或者调整写法让模块作用域不再需要这个包。动态 `import()` 只是把失败推迟到首次使用，它属于那种确实需要这个包、并且自己处理缺失的调用方；会想到它，往往说明这个依赖并不 optional，所以门禁不把它作为解法给出。
+
 ### 发布族对象
 
 这个领域里的实体是**发布族**：一组共享版本基线与 tag 命名、可整体发布的包。新增一族等于加一个子类和一条 workflow lane，不改核心。
@@ -88,9 +96,9 @@ registry 的两个行为决定了「怎么尝试一次发布」。写入之间
 |---|---|
 | `ReleaseFamily` | 一族的身份：成员发现、版本基线、tag 前缀、打包 payload 规则、已安装入口 |
 | `ReleaseMember` | 一个可发布包：目录、包名、版本、manifest |
-| `publishOrder` | 按运行时依赖的拓扑序，同层按包名排；遇到环是报错而不是随意定序 |
+| `publishOrder` | 按 npm 会安装的依赖段加 peer 声明做拓扑序，同层按包名排；安装依赖成环是报错而不是随意定序，任何排不进去的 peer 边被丢弃并点名 |
 | `pack` | 把整族打进一个目录并记录上传顺序 |
-| `verify` | 族的版本基线；发布时还要求本次运行来自该族的 tag、且成员可发布 |
+| `verify` | 族的版本基线、完整打印出来的发布顺序；发布时还要求本次运行来自该族的 tag、且成员可发布 |
 | `verify-packed-install` | 把一个或多个 pack 目录的 tarball 装进一次性 consumer，并驱动已安装的可执行入口 |
 | `publish` | 上面那三态 |
 | `process` / `tarball` | 启动命令、读取打包 tarball 的唯一正家，其中的入口守卫让每个脚本都可被 import |

package.json

@@ -95,6 +95,7 @@
     "website:build": "pnpm run docs:build",
     "verify-package-readme-limitations": "tsx scripts/verify-package-readme-limitations.ts",
     "verify-node-next-types": "tsx scripts/verify-node-next-types.ts",
+    "verify-optional-dependency-imports": "tsx scripts/verify-optional-dependency-imports.ts",
     "verify-runtime-closure": "tsx scripts/verify-runtime-closure.ts",
     "verify-vendored-links": "tsx scripts/verify-vendored-links.ts",
     "verify-cordis-config": "tsx scripts/verify-cordis-config.ts",
@@ -125,7 +126,7 @@
     "verify-module-graph": "tsx scripts/gen-module-graph.ts --check",
     "constraints": "tsx scripts/check-workspace-constraints.ts",
     "doc-sync": "tsx scripts/run-gates.ts doc-sync",
-    "hygiene": "pnpm run rescope-vendor:check && pnpm run knip && pnpm run publint && pnpm run constraints && pnpm run verify-dsh-package-licenses && pnpm run verify-package-invariants && pnpm run verify-built-package-invariants && pnpm run verify-cordis-config && pnpm run verify-node-next-types && pnpm run verify-runtime-closure && pnpm run verify-vendored-links",
+    "hygiene": "pnpm run rescope-vendor:check && pnpm run knip && pnpm run publint && pnpm run constraints && pnpm run verify-dsh-package-licenses && pnpm run verify-package-invariants && pnpm run verify-built-package-invariants && pnpm run verify-cordis-config && pnpm run verify-node-next-types && pnpm run verify-optional-dependency-imports && pnpm run verify-runtime-closure && pnpm run verify-vendored-links",
     "publish:npm-baseline": "tsx scripts/publish-npm-baseline.ts",
     "release:dsh": "tsx scripts/release/bump.ts --family dsh",
     "release:vendor": "tsx scripts/release/bump.ts --family vendor",

scripts/release/families.spec.ts

@@ -57,7 +57,7 @@ describe('release families', () => {
       member('packages/a/zebra', '@deepseek-ai/dsh-zebra'),
     ]
 
-    expect(dsh.publishOrder(members).map(entry => entry.name)).toEqual([
+    expect(dsh.publishOrder(members).order.map(entry => entry.name)).toEqual([
       '@deepseek-ai/dsh-library',
       '@deepseek-ai/dsh-consumer',
       '@deepseek-ai/dsh-zebra',
@@ -74,6 +74,92 @@ describe('release families', () => {
     expect(() => { dsh.publishOrder(members) }).toThrow(/dependency cycle/)
   })
 
+  it('publishes a peer before its consumer', () => {
+    const dsh = releaseFamily('dsh')
+    const members = [
+      member('packages/a/consumer', '@deepseek-ai/dsh-consumer', { peerDependencies: { '@deepseek-ai/dsh-zebra': 'workspace:^' } }),
+      member('packages/a/zebra', '@deepseek-ai/dsh-zebra'),
+    ]
+
+    // Name order alone would place the consumer first; the peer edge moves it.
+    expect(dsh.publishOrder(members).order.map(entry => entry.name)).toEqual([
+      '@deepseek-ai/dsh-zebra',
+      '@deepseek-ai/dsh-consumer',
+    ])
+  })
+
+  it('orders around a peer cycle rather than refusing to publish, and reports the edge it dropped', () => {
+    const dsh = releaseFamily('dsh')
+    const members = [
+      member('packages/a/left', '@deepseek-ai/dsh-left', { peerDependencies: { '@deepseek-ai/dsh-right': 'workspace:^' } }),
+      member('packages/a/right', '@deepseek-ai/dsh-right', { peerDependencies: { '@deepseek-ai/dsh-left': 'workspace:^' } }),
+    ]
+
+    // Sibling packages declare each other as peers, and npm treats an unmet peer
+    // as a warning, so this pair has to publish rather than fail the release.
+    const plan = dsh.publishOrder(members)
+    expect(plan.order.map(entry => entry.name)).toEqual([
+      '@deepseek-ai/dsh-right',
+      '@deepseek-ai/dsh-left',
+    ])
+    // One of the two edges has to give, and which one it is belongs in the log.
+    expect(plan.droppedPeerEdges).toEqual([
+      { consumer: '@deepseek-ai/dsh-right', peer: '@deepseek-ai/dsh-left' },
+    ])
+  })
+
+  it('honours an install edge even when a peer cycle surrounds it', () => {
+    const dsh = releaseFamily('dsh')
+    const members = [
+      member('packages/a/base', '@deepseek-ai/dsh-base', { peerDependencies: { '@deepseek-ai/dsh-consumer': 'workspace:^' } }),
+      member('packages/a/consumer', '@deepseek-ai/dsh-consumer', {
+        dependencies: { '@deepseek-ai/dsh-base': 'workspace:^' },
+        peerDependencies: { '@deepseek-ai/dsh-base': 'workspace:^' },
+      }),
+    ]
+
+    // The install edge is absolute: base publishes first, and the peer edge that
+    // would reverse it is the one dropped.
+    const plan = dsh.publishOrder(members)
+    expect(plan.order.map(entry => entry.name)).toEqual([
+      '@deepseek-ai/dsh-base',
+      '@deepseek-ai/dsh-consumer',
+    ])
+    expect(plan.droppedPeerEdges).toEqual([
+      { consumer: '@deepseek-ai/dsh-base', peer: '@deepseek-ai/dsh-consumer' },
+    ])
+  })
+
+  it('refuses an order that would publish a consumer before a dependency it installs', () => {
+    const dsh = releaseFamily('dsh')
+    const members = [
+      member('packages/a/alpha', '@deepseek-ai/dsh-alpha', { peerDependencies: { '@deepseek-ai/dsh-bravo': 'workspace:^' } }),
+      member('packages/a/bravo', '@deepseek-ai/dsh-bravo', { peerDependencies: { '@deepseek-ai/dsh-charlie': 'workspace:^' } }),
+      member('packages/a/charlie', '@deepseek-ai/dsh-charlie', { dependencies: { '@deepseek-ai/dsh-alpha': 'workspace:^' } }),
+    ]
+
+    // A cycle of two peer edges closed by one install edge: dropping a peer edge
+    // would order this, and the traversal drops the install edge instead. That
+    // order would publish charlie before the alpha it installs, so it is refused
+    // here rather than published.
+    expect(() => { dsh.publishOrder(members) }).toThrow(/no publish order honours @deepseek-ai\/dsh-charlie -> @deepseek-ai\/dsh-alpha/)
+  })
+
+  it('ignores devDependencies when ordering', () => {
+    const dsh = releaseFamily('dsh')
+    const members = [
+      member('packages/a/alpha', '@deepseek-ai/dsh-alpha', { devDependencies: { '@deepseek-ai/dsh-zebra': 'workspace:^' } }),
+      member('packages/a/zebra', '@deepseek-ai/dsh-zebra'),
+    ]
+
+    // A dev dependency is absent from the published package, so it must not move
+    // the consumer behind it.
+    expect(dsh.publishOrder(members).order.map(entry => entry.name)).toEqual([
+      '@deepseek-ai/dsh-alpha',
+      '@deepseek-ai/dsh-zebra',
+    ])
+  })
+
   it('applies the harness payload policy to dsh and keeps upstream payloads for vendored packages', () => {
     const dsh = releaseFamily('dsh')
     const vendor = releaseFamily('vendor')

scripts/release/families.ts

@@ -13,12 +13,47 @@ import { globSync, readFileSync } from 'node:fs'
 import { resolve } from 'node:path'
 import { validateTarballPayload } from '../publication-payload.ts'
 
-/** Dependency sections that constrain publish order: a consumer must publish after its dependency. */
-const ORDER_SECTIONS = ['dependencies', 'optionalDependencies'] as const
+/**
+ * Dependency sections a consumer must publish after, because npm resolves them
+ * when the package is installed: publishing a consumer first would leave a
+ * window where its own tree cannot be assembled.
+ */
+const INSTALL_SECTIONS = ['dependencies', 'optionalDependencies'] as const
+
+/**
+ * Peer declarations also order the publication, but they cannot constrain it.
+ * npm never installs a peer on the package's behalf — an unmet peer is a
+ * warning, not a resolution failure — and sibling packages legitimately declare
+ * each other as peers, which makes these edges the ones that close cycles. They
+ * order what they can and are dropped where they would deadlock.
+ */
+const PEER_SECTIONS = ['peerDependencies'] as const
 
 /** The workspace root manifest, which is never a release member. */
 const WORKSPACE_ROOT_PACKAGE = '@deepseek-ai/dsh-root'
 
+/** One peer declaration the publish order leaves unordered. */
+interface DroppedPeerEdge {
+  /** Package declaring the peer. */
+  readonly consumer: string
+  /** The declared peer, which publishes after `consumer` or alongside it in a cycle. */
+  readonly peer: string
+}
+
+/**
+ * A family's publish order together with the ordering it could not honour.
+ *
+ * The dropped edges are part of the result rather than a detail of forming it:
+ * a release drops real ordering constraints, and the operator reading the pack
+ * log is the only one who can judge whether a newly dropped edge is expected.
+ */
+export interface PublishPlan {
+  /** Members in publish order. */
+  readonly order: readonly ReleaseMember[]
+  /** Peer declarations left unordered, in the order the traversal reached them. */
+  readonly droppedPeerEdges: readonly DroppedPeerEdge[]
+}
+
 /** One publishable package of a release family. */
 export interface ReleaseMember {
   /** Repository-relative package directory, for example `packages/core/session`. */
@@ -107,45 +142,122 @@ export abstract class ReleaseFamily {
   }
 
   /**
-   * Order members so every package publishes after the family members it depends on.
+   * Order members so every package publishes after the family members it
+   * depends on, which is what makes a partial publication self-consistent: an
+   * interrupted run leaves a prefix whose packages never point at something
+   * absent from the registry.
+   *
+   * Install edges are honoured absolutely — a cycle among them is a defect this
+   * reports rather than works around. Peer edges order what they can and are
+   * dropped where honouring one would deadlock: sibling packages declare each
+   * other as peers, and npm treats an unmet peer as a warning rather than a
+   * resolution failure ([rationale](../../.agents/notes/implemented/process/2026-08-10-npm-release-sequences.md)).
+   * Every dropped edge is reported, because dropping one is a decision about a
+   * real release rather than an implementation detail.
    * @param members - this family's members.
-   * @returns The same members in publish order; ties break by name for determinism.
+   * @returns The order, ties broken by name for determinism, and the peer edges it left unordered.
    */
-  publishOrder(members: readonly ReleaseMember[]): ReleaseMember[] {
+  publishOrder(members: readonly ReleaseMember[]): PublishPlan {
     const byName = new Map(members.map(member => [member.name, member]))
-    const ordered: ReleaseMember[] = []
-    const placed = new Set<string>()
-    const visiting = new Set<string>()
+    const byNameSorted = [...members].sort((left, right) => left.name.localeCompare(right.name))
+    const edges = (member: ReleaseMember, sections: readonly string[]): ReleaseMember[] =>
+      this.orderEdges(member, byName, sections)
 
-    const visit = (member: ReleaseMember, path: readonly string[]): void => {
-      if (placed.has(member.name)) return
-      if (visiting.has(member.name)) {
+    // Install edges alone must be acyclic, and that is checked on its own graph:
+    // a peer edge leading into an install edge would otherwise read as a cycle
+    // where the install edges are perfectly orderable.
+    const installVisiting = new Set<string>()
+    const installDone = new Set<string>()
+    const checkInstall = (member: ReleaseMember, path: readonly string[]): void => {
+      if (installDone.has(member.name)) return
+      if (installVisiting.has(member.name)) {
         throw new Error(`dependency cycle in release family ${this.id}: ${[...path, member.name].join(' -> ')}`)
       }
-      visiting.add(member.name)
-      for (const dependency of this.orderEdges(member, byName)) {
-        visit(dependency, [...path, member.name])
+      installVisiting.add(member.name)
+      for (const dependency of edges(member, INSTALL_SECTIONS)) checkInstall(dependency, [...path, member.name])
+      installVisiting.delete(member.name)
+      installDone.add(member.name)
+    }
+    for (const member of byNameSorted) checkInstall(member, [])
+
+    // Emit the order over both kinds of edge. A node already on the stack closes
+    // a cycle, and that cycle carries at least one peer edge because the install
+    // edges were just proved acyclic — but the back edge that reaches the stacked
+    // node is not necessarily the peer one, so the post-condition below decides
+    // whether the emitted order survived.
+    const ordered: ReleaseMember[] = []
+    const droppedPeerEdges: DroppedPeerEdge[] = []
+    const placed = new Set<string>()
+    const onStack = new Set<string>()
+    // Members reachable from one member through install edges. A peer edge is
+    // dropped when the peer installs the member declaring it: honouring it would
+    // emit a package before something it installs, and the install edge wins.
+    const installClosure = (member: ReleaseMember): Set<string> => {
+      const reached = new Set<string>()
+      const walk = (current: ReleaseMember): void => {
+        for (const dependency of edges(current, INSTALL_SECTIONS)) {
+          if (reached.has(dependency.name)) continue
+          reached.add(dependency.name)
+          walk(dependency)
+        }
       }
-      visiting.delete(member.name)
+      walk(member)
+      return reached
+    }
+    const visit = (member: ReleaseMember): void => {
+      if (placed.has(member.name) || onStack.has(member.name)) return
+      onStack.add(member.name)
+      for (const dependency of edges(member, INSTALL_SECTIONS)) visit(dependency)
+      for (const peer of edges(member, PEER_SECTIONS)) {
+        if (installClosure(peer).has(member.name)) {
+          droppedPeerEdges.push({ consumer: member.name, peer: peer.name })
+          continue
+        }
+        // A peer already on the stack is an ancestor, so it publishes after this
+        // member rather than before it: the edge is dropped, not honoured.
+        if (onStack.has(peer.name)) droppedPeerEdges.push({ consumer: member.name, peer: peer.name })
+        visit(peer)
+      }
+      onStack.delete(member.name)
       placed.add(member.name)
       ordered.push(member)
     }
+    for (const member of byNameSorted) visit(member)
 
-    for (const member of [...members].sort((left, right) => left.name.localeCompare(right.name))) {
-      visit(member, [])
+    // A cycle mixing both kinds of edge can put an install edge's target on the
+    // stack, where the traversal skips it like a peer edge and emits a consumer
+    // before something it installs. Nothing downstream can detect that, and it
+    // would only surface as an unresolvable install for whoever consumes the
+    // published packages, so the emitted order is checked against the edges it
+    // exists to honour.
+    const position = new Map(ordered.map((entry, index) => [entry.name, index]))
+    for (const [index, member] of ordered.entries()) {
+      for (const dependency of edges(member, INSTALL_SECTIONS)) {
+        const dependencyIndex = position.get(dependency.name)
+        if (dependencyIndex !== undefined && dependencyIndex < index) continue
+        throw new Error(
+          `release family ${this.id}: no publish order honours ${member.name} -> ${dependency.name};`
+          + ' a cycle mixing peer and dependency declarations reaches this dependency through a peer edge',
+        )
+      }
     }
-    return ordered
+    return { order: ordered, droppedPeerEdges }
   }
 
   /**
-   * The family members one member depends on at runtime.
+   * The family members one member declares in the given sections.
    * @param member - the dependent member.
    * @param byName - every family member by package name.
-   * @returns Dependencies inside this family, sorted by name.
+   * @param sections - manifest sections to read.
+   * @returns Members of this family named there, sorted by name.
    */
-  private orderEdges(member: ReleaseMember, byName: ReadonlyMap<string, ReleaseMember>): ReleaseMember[] {
+  private orderEdges(
+    member: ReleaseMember,
+    byName: ReadonlyMap<string, ReleaseMember>,
+    sections: readonly string[],
+  ): ReleaseMember[] {
     const edges: ReleaseMember[] = []
-    for (const section of ORDER_SECTIONS) {
+    for (const section of sections) {
       const dependencies = member.manifest[section]
       if (dependencies === null || typeof dependencies !== 'object' || Array.isArray(dependencies)) continue
       for (const name of Object.keys(dependencies)) {

scripts/release/pack.ts

@@ -45,7 +45,7 @@ function main(): void {
   const family = releaseFamily(values.family)
   const root = process.cwd()
   const destination = resolve(root, values.out ?? DEFAULT_OUTPUT)
-  const members = family.publishOrder(family.members(root))
+  const members = family.publishOrder(family.members(root)).order
   family.verifyVersions(members)
 
   rmSync(destination, { recursive: true, force: true })

scripts/release/process.ts

@@ -38,6 +38,40 @@ export function attempt(command: string, args: readonly string[], options: RunOp
   return { status: result.status, stdout: result.stdout, stderr: result.stderr }
 }
 
+/**
+ * Run a command, capture its output, and echo it once the command exits.
+ *
+ * A step that both shows what a command said and classifies its own failure
+ * needs both halves: the output has to reach the workflow log, and the caller has
+ * to read it to decide whether a failure is worth retrying.
+ *
+ * This is not live progress. `spawnSync` returns only after the child exits, so
+ * nothing appears while the command runs, and the two streams are echoed one
+ * after the other — all of stdout, then all of stderr — which loses their
+ * interleaving. For an npm publish that matters in one visible way: `npm notice`
+ * lines go to stderr while the `+ name@version` confirmation goes to stdout, so
+ * the log shows the confirmation first. Live progress would need an
+ * asynchronous spawn with data listeners.
+ * @param command - executable name.
+ * @param args - command arguments.
+ * @param options - working directory and environment.
+ * @returns The exit status and captured streams.
+ */
+export function attemptEchoed(command: string, args: readonly string[], options: RunOptions = {}): CommandResult {
+  const result = spawnSync(command, [...args], {
+    cwd: options.cwd,
+    env: options.env,
+    encoding: 'utf8',
+    // 'inherit' would leave nothing to capture, so the streams are piped and
+    // echoed instead.
+    stdio: ['inherit', 'pipe', 'pipe'],
+  })
+  if (result.error !== undefined) throw result.error
+  if (result.stdout !== '') process.stdout.write(result.stdout)
+  if (result.stderr !== '') process.stderr.write(result.stderr)
+  return { status: result.status, stdout: result.stdout, stderr: result.stderr }
+}
+
 /**
  * Run a command, capture its standard output, and fail on a non-zero exit.
  * @param command - executable name.

scripts/release/publish.ts

@@ -18,7 +18,7 @@ import { join, resolve } from 'node:path'
 import { setTimeout as sleep } from 'node:timers/promises'
 import { parseArgs } from 'node:util'
 import { releaseFamily } from './families.ts'
-import { attempt, isEntry } from './process.ts'
+import { attempt, attemptEchoed, isEntry } from './process.ts'
 import { packedIdentity, readPublishOrder } from './tarball.ts'
 
 /**
@@ -102,7 +102,7 @@ async function publishTarball(tarball: string, name: string, version: string): P
     // command-line flag could not serve both and would override the manifest
     // that does. Each packed manifest decides, and
     // check-workspace-constraints holds every manifest to its sequence's level.
-    const result = attempt('npm', ['publish', tarball, ...tagArgs])
+    const result = attemptEchoed('npm', ['publish', tarball, ...tagArgs])
     const output = `${result.stdout}${result.stderr}`
     if (result.status === 0) return
 
@@ -136,9 +136,15 @@ async function main(): Promise<void> {
   const family = releaseFamily(values.family)
   const directory = resolve(process.cwd(), values.from)
 
+  // Every entry in the order settles as either published or already present, so
+  // one counter answers "how far along is this run" for whoever is watching a
+  // release that takes minutes per family.
+  const order = readPublishOrder(directory)
+  const total = String(order.length)
   let published = 0
   let skipped = 0
-  for (const filename of readPublishOrder(directory)) {
+  for (const [index, filename] of order.entries()) {
+    const progress = `[${String(index + 1)}/${total}]`
     const tarball = join(directory, filename)
     const { name, version } = packedIdentity(tarball)
     const state = registryState(name, version)
@@ -151,7 +157,7 @@ async function main(): Promise<void> {
           + '\nBump the version, or investigate why the build is not reproducible.',
         )
       }
-      console.log(`release publish: ${name}@${version} already published, skipping`)
+      console.log(`release publish: ${progress} ${name}@${version} already published, skipping`)
       skipped += 1
       continue
     }
@@ -159,11 +165,14 @@ async function main(): Promise<void> {
     // only skips does not wait at all.
     if (published > 0) await sleep(PUBLISH_SPACING_MS)
     await publishTarball(tarball, name, version)
-    console.log(`release publish: ${name}@${version} published`)
+    console.log(`release publish: ${progress} ${name}@${version} published`)
     published += 1
   }
 
-  console.log(`release publish: family ${family.id}, ${String(published)} published, ${String(skipped)} already present`)
+  console.log(
+    `release publish: family ${family.id}, ${total} member(s),`
+    + ` ${String(published)} published, ${String(skipped)} already present`,
+  )
 }
 
 if (isEntry(import.meta.url)) await main()

scripts/release/verify.ts

@@ -9,7 +9,33 @@
 
 import { parseArgs } from 'node:util'
 import { isEntry } from './process.ts'
-import { releaseFamily, type ReleaseFamily, type ReleaseMember } from './families.ts'
+import { releaseFamily, type PublishPlan, type ReleaseFamily, type ReleaseMember } from './families.ts'
+
+/**
+ * Print the publish order the release will follow, and the peer declarations it
+ * leaves unordered.
+ *
+ * The order is the release's own plan: an interrupted publication leaves exactly
+ * a prefix of it, so reading it is how anyone judges what a partial run left on
+ * the registry, and printing it on every pull request is what makes a change to
+ * the order reviewable rather than only observable during a publication.
+ * @param family - the release family.
+ * @param plan - the resolved order and its dropped edges.
+ */
+function reportPublishOrder(family: ReleaseFamily, plan: PublishPlan): void {
+  console.log(`release verify: publish order for family ${family.id}, ${String(plan.order.length)} member(s):`)
+  const width = String(plan.order.length).length
+  for (const [index, member] of plan.order.entries()) {
+    console.log(`  ${String(index + 1).padStart(width, ' ')}  ${member.name}@${member.version}`)
+  }
+  if (plan.droppedPeerEdges.length === 0) return
+  console.log(
+    `release verify: ${String(plan.droppedPeerEdges.length)} peer declaration(s) publish unordered,`
+    + ' because the peer cannot precede the package declaring it without contradicting a dependency edge'
+    + ' or its own cycle. npm treats an unmet peer as a warning, so this orders nothing and blocks nothing:',
+  )
+  for (const edge of plan.droppedPeerEdges) console.log(`  ${edge.consumer} -> ${edge.peer}`)
+}
 
 /**
  * Assert every member may be published: npm refuses a `private` package.
@@ -55,6 +81,16 @@ function main(): void {
   const family = releaseFamily(values.family)
   const members = family.members(process.cwd())
   family.verifyVersions(members)
+  // Resolve the publish order here, before the build: an install-edge cycle
+  // makes the order unrepresentable, and that has to surface at the first gate
+  // rather than when pack is already writing tarballs.
+  const plan = family.publishOrder(members)
+  if (plan.order.length !== members.length) {
+    throw new Error(
+      `release family ${family.id}: publish order covers ${String(plan.order.length)} of ${String(members.length)} members`,
+    )
+  }
+  reportPublishOrder(family, plan)
 
   const publishing = process.env.RELEASE_PUBLISH === 'true'
   if (publishing) {
@@ -64,7 +100,11 @@ function main(): void {
 
   const versions = [...new Set(members.map(member => member.version))]
   const summary = versions.length === 1 ? versions[0] : `${String(versions.length)} versions`
-  console.log(`release verify: family ${family.id}, ${String(members.length)} member(s), ${summary}${publishing ? ', publish gates passed' : ''}`)
+  console.log(
+    `release verify: family ${family.id}, ${String(members.length)} member(s), ${summary},`
+    + ` publish order resolved, ${String(plan.droppedPeerEdges.length)} peer declaration(s) unordered`
+    + (publishing ? ', publish gates passed' : ''),
+  )
 }
 
 if (isEntry(import.meta.url)) main()

scripts/run-gates.ts

@@ -249,6 +249,9 @@ function ciSharedStaticGates(): Gate[] {
     pnpmScript('dsh-package-licenses', 'verify-dsh-package-licenses', { label: 'DSH package licenses' }),
     pnpmScript('package-invariants', 'verify-package-invariants', { label: 'package invariants' }),
     pnpmScript('cordis-config', 'verify-cordis-config', { label: 'Cordis config' }),
+    pnpmScript('optional-dependency-imports', 'verify-optional-dependency-imports', {
+      label: 'optional dependency imports',
+    }),
     pnpmScript('issue-management', 'test:issue-management', { label: 'Issue management policy' }),
   ]
 }
@@ -565,6 +568,9 @@ function hygieneLeafGates(options: { artifactNeeds?: string[] } = {}): Gate[] {
       label: 'node-next types',
       ...artifactOptions,
     }),
+    pnpmScript('optional-dependency-imports', 'verify-optional-dependency-imports', {
+      label: 'optional dependency imports',
+    }),
   ]
 }
 

scripts/ts-project.ts

@@ -11,6 +11,12 @@ interface ProjectGraph {
   options: ts.CompilerOptions
 }
 
+/**
+ * A compiler face: the two aggregates a repository-wide program may seed from.
+ * The root solution is never one of them.
+ */
+export type CompilerFace = 'host' | 'client'
+
 /** TypeScript config host shared by repository scripts. */
 export const repositoryConfigHost: ts.ParseConfigFileHost = {
   useCaseSensitiveFileNames: ts.sys.useCaseSensitiveFileNames,
@@ -24,12 +30,12 @@ export const repositoryConfigHost: ts.ParseConfigFileHost = {
 }
 
 /**
- * Parse the host aggregate tsconfig and flatten all referenced projects into one
+ * Parse one face aggregate tsconfig and flatten all referenced projects into one
  * semantic graph. Never seed the root solution: flattening host+client into one
  * program collides the cordis Context merges.
  */
-function loadProjectGraph(projectRoot: string): ProjectGraph {
-  const rootConfigPath = resolve(projectRoot, 'tsconfig.host.json')
+function loadProjectGraph(projectRoot: string, face: CompilerFace): ProjectGraph {
+  const rootConfigPath = resolve(projectRoot, `tsconfig.${face}.json`)
   const rootConfig = parseConfig(rootConfigPath)
   const rootNames = new Set<string>()
   const visited = new Set<string>()
@@ -81,8 +87,12 @@ export class TypeScriptProject {
   /** The checker shared by every semantic query in this project. */
   readonly checker: ts.TypeChecker
 
-  constructor(private readonly projectRoot: string) {
-    const graph = loadProjectGraph(projectRoot)
+  /**
+   * @param projectRoot - repository root the program is seeded and reported from.
+   * @param face - which compiler face aggregate to flatten.
+   */
+  constructor(readonly projectRoot: string, face: CompilerFace = 'host') {
+    const graph = loadProjectGraph(projectRoot, face)
     this.program = ts.createProgram(graph.rootNames, semanticCompilerOptions(graph.options))
     this.checker = this.program.getTypeChecker()
   }

scripts/verify-optional-dependency-imports.spec.ts

@@ -0,0 +1,130 @@
+/**
+ * Tests for the optional-dependency load gate: which import and re-export forms
+ * survive emit, and therefore load a package the installed tree may not carry.
+ *
+ * The expectations here match what `tsc` emits with `verbatimModuleSyntax` off:
+ * `import type`, `import {}`, an inline `type` specifier, and a named binding
+ * that resolves to a type all disappear; a bare import, a value binding, and a
+ * star re-export remain.
+ */
+
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { dirname, join } from 'node:path'
+import { afterAll, describe, expect, it } from 'vitest'
+import { TypeScriptProject } from './ts-project.ts'
+import { collectOptionalImportViolations } from './verify-optional-dependency-imports.ts'
+
+const FIXTURE: Record<string, string> = {
+  'tsconfig.host.json': JSON.stringify({
+    compilerOptions: {
+      target: 'es2022',
+      module: 'esnext',
+      moduleResolution: 'bundler',
+      noEmit: true,
+      skipLibCheck: true,
+      types: [],
+      paths: {
+        '@f/opt': ['./packages/f/opt/src/index.ts'],
+        '@f/hard': ['./packages/f/hard/src/index.ts'],
+      },
+    },
+    include: ['packages/**/*.ts'],
+  }),
+
+  'packages/f/opt/package.json': JSON.stringify({ name: '@f/opt', version: '0.0.1' }),
+  'packages/f/opt/src/index.ts': [
+    'export interface Shape { a: number }',
+    'export const runtimeValue = 1',
+    '',
+  ].join('\n'),
+
+  'packages/f/hard/package.json': JSON.stringify({ name: '@f/hard', version: '0.0.1' }),
+  'packages/f/hard/src/index.ts': 'export const hardValue = 2\n',
+
+  // The consumer allows @f/opt to be absent and requires @f/hard.
+  'packages/f/consumer/package.json': JSON.stringify({
+    name: '@f/consumer',
+    version: '0.0.1',
+    dependencies: { '@f/hard': '*' },
+    peerDependencies: { '@f/opt': '*' },
+    peerDependenciesMeta: { '@f/opt': { optional: true } },
+  }),
+
+  // Elided by the compiler, so each of these is allowed.
+  'packages/f/consumer/src/allowed-type-only.ts': [
+    "import type {} from '@f/opt'",
+    'export const a = 1',
+    '',
+  ].join('\n'),
+  'packages/f/consumer/src/allowed-empty.ts': [
+    "import {} from '@f/opt'",
+    'export const b = 1',
+    '',
+  ].join('\n'),
+  'packages/f/consumer/src/allowed-inline-type.ts': [
+    "import { type Shape } from '@f/opt'",
+    'export const c: Shape = { a: 1 }',
+    '',
+  ].join('\n'),
+  'packages/f/consumer/src/allowed-type-binding.ts': [
+    "import { Shape } from '@f/opt'",
+    'export const d: Shape = { a: 1 }',
+    '',
+  ].join('\n'),
+  'packages/f/consumer/src/allowed-type-reexport.ts': [
+    "export type { Shape } from '@f/opt'",
+    '',
+  ].join('\n'),
+  // A hard dependency may be loaded at module scope; only optional ones may not.
+  'packages/f/consumer/src/allowed-hard-dependency.ts': [
+    "import { hardValue } from '@f/hard'",
+    'export const e = hardValue',
+    '',
+  ].join('\n'),
+
+  // Kept by the compiler, so each of these loads a package that may be absent.
+  'packages/f/consumer/src/rejected-bare.ts': [
+    "import '@f/opt'",
+    'export const f = 1',
+    '',
+  ].join('\n'),
+  'packages/f/consumer/src/rejected-value.ts': [
+    "import { runtimeValue } from '@f/opt'",
+    'export const g = runtimeValue',
+    '',
+  ].join('\n'),
+  'packages/f/consumer/src/rejected-star-reexport.ts': [
+    "export * from '@f/opt'",
+    '',
+  ].join('\n'),
+}
+
+const root = mkdtempSync(join(tmpdir(), 'optional-imports-'))
+for (const [rel, content] of Object.entries(FIXTURE)) {
+  mkdirSync(dirname(join(root, rel)), { recursive: true })
+  writeFileSync(join(root, rel), content)
+}
+const violations = collectOptionalImportViolations(new TypeScriptProject(root))
+
+afterAll(() => {
+  rmSync(root, { recursive: true, force: true })
+})
+
+describe('optional dependency loads', () => {
+  it('reports every form the compiler keeps, and nothing else', () => {
+    expect(violations.map(violation => violation.split(' loads ')[0])).toEqual([
+      'packages/f/consumer/src/rejected-bare.ts:1',
+      'packages/f/consumer/src/rejected-star-reexport.ts:1',
+      'packages/f/consumer/src/rejected-value.ts:1',
+    ])
+  })
+
+  it('names the package, the declaration that made it optional, and the way out', () => {
+    expect(violations[0]).toBe(
+      'packages/f/consumer/src/rejected-bare.ts:1 loads @f/opt at module scope,'
+      + ' declared optional in peerDependenciesMeta; import it as a type,'
+      + ' or restructure so module scope does not need it',
+    )
+  })
+})

scripts/verify-optional-dependency-imports.ts

@@ -0,0 +1,214 @@
+/**
+ * Reject a static value import of an optional dependency.
+ *
+ * A dependency declared in `optionalDependencies`, or as a peer carrying
+ * `peerDependenciesMeta.<name>.optional`, may be absent from an installed tree —
+ * that absence is what "optional" promises a consumer. A static import is
+ * evaluated when the importing module loads, so one absent package turns
+ * "this capability is unavailable" into a load failure for everything that
+ * reaches the importing module.
+ *
+ * The way out, in order: import it as a type, which emits nothing and is all
+ * that declaration merging needs; or restructure so nothing at module scope
+ * needs the package. A dynamic `import()` only moves the failure to first use,
+ * so it belongs to a caller that genuinely requires the package and handles its
+ * absence — it is a last resort, not the default answer, and reaching for it is
+ * a sign the dependency is not optional.
+ *
+ * Value-vs-type is decided against a bound Program rather than the import
+ * syntax, because `verbatimModuleSyntax` is off: a named import used only in
+ * type positions is elided and does not load anything. The decision is
+ * deliberately conservative in one direction — a value binding the compiler
+ * would elide because nothing references it in a value position is still
+ * reported, and the fix it asks for (`import type`, or dropping the binding) is
+ * what the published package wants regardless. Both compiler faces are scanned,
+ * and only files that ship — a published package's `src` — are subject.
+ */
+
+import { existsSync, readFileSync } from 'node:fs'
+import { resolve } from 'node:path'
+import ts from 'typescript'
+import { TypeScriptProject, type CompilerFace } from './ts-project.ts'
+
+const root = resolve(import.meta.dirname, '..')
+
+/** Directories whose `src` ships as a published package. */
+const PUBLISHED_SOURCE = /^(?:packages\/[^/]+\/[^/]+|apps\/[^/]+)\/src\//
+
+/** How a manifest marked a dependency optional, for the violation message. */
+type OptionalKind = 'optionalDependencies' | 'peerDependenciesMeta'
+
+/**
+ * The package name a module specifier resolves to.
+ * @param specifier - an import specifier, possibly a subpath.
+ * @returns The bare package name, keeping a leading scope.
+ */
+function packageOf(specifier: string): string {
+  const parts = specifier.split('/')
+  return specifier.startsWith('@') ? parts.slice(0, 2).join('/') : parts[0] ?? specifier
+}
+
+/**
+ * Read a manifest field as a record.
+ * @param manifest - parsed manifest.
+ * @param field - field name.
+ * @returns The field value, or an empty record.
+ */
+function record(manifest: Record<string, unknown>, field: string): Record<string, unknown> {
+  const value = manifest[field]
+  if (value === null || typeof value !== 'object' || Array.isArray(value)) return {}
+  return value as Record<string, unknown>
+}
+
+/**
+ * The dependencies one manifest allows to be absent.
+ * @param manifest - parsed manifest.
+ * @returns Each optional package name and how it was marked.
+ */
+function optionalDependencies(manifest: Record<string, unknown>): Map<string, OptionalKind> {
+  const optional = new Map<string, OptionalKind>()
+  for (const name of Object.keys(record(manifest, 'optionalDependencies'))) {
+    optional.set(name, 'optionalDependencies')
+  }
+  const peers = record(manifest, 'peerDependencies')
+  for (const [name, meta] of Object.entries(record(manifest, 'peerDependenciesMeta'))) {
+    if (meta === null || typeof meta !== 'object') continue
+    if ((meta as Record<string, unknown>).optional !== true) continue
+    // A meta entry for an undeclared peer is check-workspace-constraints' business.
+    if (!(name in peers)) continue
+    optional.set(name, 'peerDependenciesMeta')
+  }
+  return optional
+}
+
+/** One package directory's optional dependencies, resolved once per directory. */
+const optionalByDirectory = new Map<string, Map<string, OptionalKind>>()
+
+/**
+ * The optional dependencies of the package owning a source file.
+ * @param projectRoot - root the relative path is resolved against.
+ * @param relativePath - repository-relative path of a source file.
+ * @returns That package's optional dependencies, empty when it declares none.
+ */
+function optionalFor(projectRoot: string, relativePath: string): Map<string, OptionalKind> {
+  const directory = resolve(projectRoot, relativePath.slice(0, relativePath.indexOf('/src/')))
+  const cached = optionalByDirectory.get(directory)
+  if (cached !== undefined) return cached
+  const manifestPath = resolve(directory, 'package.json')
+  const parsed: unknown = existsSync(manifestPath) ? JSON.parse(readFileSync(manifestPath, 'utf8')) : {}
+  const manifest = parsed !== null && typeof parsed === 'object' && !Array.isArray(parsed)
+    ? parsed as Record<string, unknown>
+    : {}
+  const optional = optionalDependencies(manifest)
+  optionalByDirectory.set(directory, optional)
+  return optional
+}
+
+/**
+ * Whether one binding of an import or re-export names a value.
+ * @param name - the local binding name node.
+ * @param checker - the program's checker.
+ * @returns True when the binding carries value meaning, and on an unresolved
+ * symbol, so an unresolvable binding fails closed.
+ */
+function bindsValue(name: ts.Identifier | ts.StringLiteral, checker: ts.TypeChecker): boolean {
+  const symbol = checker.getSymbolAtLocation(name)
+  if (symbol === undefined) return true
+  const target = (symbol.flags & ts.SymbolFlags.Alias) === 0 ? symbol : checker.getAliasedSymbol(symbol)
+  return (target.flags & ts.SymbolFlags.Value) !== 0
+}
+
+/**
+ * Whether an import declaration loads its module at run time.
+ * @param declaration - the import declaration.
+ * @param checker - the program's checker.
+ * @returns True when the emitted module keeps the import.
+ */
+function importLoadsModule(declaration: ts.ImportDeclaration, checker: ts.TypeChecker): boolean {
+  const clause = declaration.importClause
+  // A bare `import 'x'` is kept for its side effects.
+  if (clause === undefined) return true
+  // Only the type phase erases the import. `import defer` still resolves and
+  // links the module, deferring evaluation alone, so an absent package fails
+  // exactly as it would without the modifier.
+  if (clause.phaseModifier === ts.SyntaxKind.TypeKeyword) return false
+  if (clause.name !== undefined) return true
+  const bindings = clause.namedBindings
+  if (bindings === undefined || ts.isNamespaceImport(bindings)) return true
+  return bindings.elements.some(element => !element.isTypeOnly && bindsValue(element.name, checker))
+}
+
+/**
+ * Whether a re-export loads its module at run time.
+ * @param declaration - the export declaration, which carries a module specifier.
+ * @param checker - the program's checker.
+ * @returns True when the emitted module keeps the re-export.
+ */
+function exportLoadsModule(declaration: ts.ExportDeclaration, checker: ts.TypeChecker): boolean {
+  if (declaration.isTypeOnly) return false
+  const clause = declaration.exportClause
+  // `export * from 'x'` re-exports whatever values the module has.
+  if (clause === undefined || ts.isNamespaceExport(clause)) return true
+  return clause.elements.some(element => !element.isTypeOnly && bindsValue(element.name, checker))
+}
+
+/**
+ * Collect every static value import of an optional dependency in one face.
+ * @param project - a bound repository project.
+ * @returns One message per violation, sorted by location.
+ */
+export function collectOptionalImportViolations(project: TypeScriptProject): string[] {
+  const checker = project.checker
+  const violations: string[] = []
+  for (const sourceFile of project.sourceFiles()) {
+    if (sourceFile.isDeclarationFile) continue
+    const relativePath = project.relativePath(sourceFile)
+    if (!PUBLISHED_SOURCE.test(relativePath)) continue
+    const optional = optionalFor(project.projectRoot, relativePath)
+    if (optional.size === 0) continue
+
+    for (const statement of sourceFile.statements) {
+      const isImport = ts.isImportDeclaration(statement)
+      if (!isImport && !ts.isExportDeclaration(statement)) continue
+      const specifierNode = statement.moduleSpecifier
+      if (specifierNode === undefined || !ts.isStringLiteral(specifierNode)) continue
+      const kind = optional.get(packageOf(specifierNode.text))
+      if (kind === undefined) continue
+      const loads = isImport
+        ? importLoadsModule(statement, checker)
+        : exportLoadsModule(statement, checker)
+      if (!loads) continue
+      const { line } = sourceFile.getLineAndCharacterOfPosition(statement.getStart(sourceFile))
+      violations.push(
+        `${relativePath}:${String(line + 1)} loads ${specifierNode.text} at module scope,`
+        + ` declared optional in ${kind}; import it as a type, or restructure so module scope does not need it`,
+      )
+    }
+  }
+  return violations.sort((left, right) => left.localeCompare(right))
+}
+
+/** CLI entry: list every violation and exit 1, or confirm the invariant holds. */
+function main(): void {
+  const faces: readonly CompilerFace[] = ['host', 'client']
+  const violations = new Set<string>()
+  for (const face of faces) {
+    for (const violation of collectOptionalImportViolations(new TypeScriptProject(root, face))) {
+      violations.add(violation)
+    }
+  }
+  if (violations.size === 0) {
+    console.log('verify-optional-dependency-imports: no optional dependency is loaded at module scope.')
+    return
+  }
+  console.error(`verify-optional-dependency-imports: ${String(violations.size)} optional dependency load(s) at module scope:`)
+  for (const violation of [...violations].sort((left, right) => left.localeCompare(right))) {
+    console.error(`  ${violation}`)
+  }
+  process.exit(1)
+}
+
+// Run only when invoked as a script, not when imported by a test.
+if (process.argv[1] && import.meta.filename === resolve(process.argv[1])) {
+  main()
+}