[plugin-helpers] fix: satisfy strict mode in plugin-helpers (#4683)

[eddeee888]

Description

Part of the strict: true tracker #10985. This fixes the 23 errors utils/plugins-helpers hits under strict mode, corrects two exported types that were wrong, and types oldVisit's visitor param.

Local fixes, no new casts

• federation.ts
  • reduce calls get a type argument (reduce<string[]>, reduce<ReferenceSelectionSet>) instead of an untyped []/{} start value (TS2769, TS2488, TS7053).
  • getDirectivesByName accepts graphql's Maybe<FieldDefinitionNode> (TS2345).
  • graphql's optional directives/arguments get || [] fallbacks (TS18048).
  • A federation directive without a fields argument, or with a fields value that doesn't parse to a query, throws a descriptive error. It used to throw a TypeError.
• helpers.ts
  • normalizeConfig uses reduce<Types.ConfiguredPlugin[]> (TS2322, TS2769).
  • isUsingTypes's parent param allows undefined like graphql's visitor does (TS2769).
  • An operation whose root type is missing from the schema throws a descriptive error instead of a TypeError (TS2533).
  • A null type name no longer goes to getType (TS2345).
• utils.ts: mergeOutputs builds local prepend/append arrays instead of reusing ComplexPluginOutput, whose fields are optional (TS18048, TS2488).

Exported types corrected

• ProfilerEvent.cat is optional. It matches Profiler.run's optional cat and the Trace Event format (TS2322). Trace files are unchanged.
• ReferenceSelectionSet (exposed through FederationMeta) is recursive: { [field: string]: true | ReferenceSelectionSet }. It used to be Record<string, boolean>, but nested selections like company { taxCode } produce objects, not booleans. DirectiveSelectionSet.selection changes to match.

oldVisit typed

• The visitor param is the new exported OldVisitor type: enter/leave maps keyed by AST node kind. Their callbacks get the typed node plus graphql's key, parent, path and ancestors (TS7006 on the federation visitor callbacks).
• The callbacks are declared with method syntax, the same trick as @types/react's bivarianceHack. That way visitor class instances whose methods declare narrower param types (such as ancestors: ASTNode[]) are still accepted without casts.
• Because of this, typescript's and typescript-operations' InputValueDefinition visitor methods take path and ancestors as required. graphql's visit always passes them.

Generated output is unchanged. The strict typecheck goes from 228 to 205 errors: 0 in plugins-helpers, and no package's count goes up.

This is the most thorough of the three options discussed. The other two were "local fixes only" and "also correct the two exported types". We picked it so the exported types and oldVisit get typed properly instead of worked around.

Related #4683

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Ran tsc --noEmit -p tsconfig.json with the tracker's strict tsconfig.json: 0 errors under packages/utils/plugins-helpers, and no other package's count goes up.
• pnpm types:check (the current non-strict config) is clean.
• vitest for plugin-helpers, typescript, typescript-operations, typescript-resolvers, typescript-document-nodes, typed-document-node, visitor-plugin-common and core passes. The cli project has 72 failures about plugin/preset resolution in this environment. The same tests fail on a clean master checkout.

🤖 Generated with Claude Code

https://claude.ai/code/session_01UcXG2hnduGFaXB3oCtb8UX

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[changeset-bot]

🦋 Changeset detected

Latest commit: db315f7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@graphql-codegen/plugin-helpers	Patch
@graphql-codegen/typescript	Patch
@graphql-codegen/typescript-operations	Patch

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[github-actions]

🚀 Snapshot Release (alpha)

The latest changes of this PR are available as alpha on npm (based on the declared changesets):

Package	Version	Info
@graphql-codegen/time	7.1.1-alpha-20261001102714-db315f7d811d91a74e4b24f6d73df1b0fcb44619	npm ↗︎ unpkg ↗︎
@graphql-codegen/visitor-plugin-common	7.2.8-alpha-20261001102714-db315f7d811d91a74e4b24f6d73df1b0fcb44619	npm ↗︎ unpkg ↗︎
@graphql-codegen/typescript-operations	6.1.10-alpha-20261001102714-db315f7d811d91a74e4b24f6d73df1b0fcb44619	npm ↗︎ unpkg ↗︎
@graphql-codegen/typescript	6.1.1-alpha-20261001102714-db315f7d811d91a74e4b24f6d73df1b0fcb44619	npm ↗︎ unpkg ↗︎
@graphql-codegen/client-preset	6.2.1-alpha-20261001102714-db315f7d811d91a74e4b24f6d73df1b0fcb44619	npm ↗︎ unpkg ↗︎
@graphql-codegen/plugin-helpers	7.4.1-alpha-20261001102714-db315f7d811d91a74e4b24f6d73df1b0fcb44619	npm ↗︎ unpkg ↗︎

[eddeee888]

What's the difference between visit vs oldVisit? Keep it short dotpoints

[eddeee888]

• Visitor shape: visit (graphql, 17.0.2 here) groups handlers by kind first: { Field: { enter, leave } }. A top-level enter/leave is a single function that runs for every node. oldVisit takes the older "parallel" shape, where enter/leave are maps by kind: { leave: { Field() {}, Document() {} } }. graphql-js v16 dropped that shape (it was the 4th form in the v15 visit docs).
• What oldVisit does: it reshapes { enter: { K }, leave: { K } } into { K: { enter, leave } } and calls visit (oldVisit.ts#L55-L72). It passes any other keys straight through. Traversal, replacing nodes with what leave returns, and the (node, key, parent, path, ancestors) args are all visit's own.
• Why it's kept: every visitor class is used as oldVisit(ast, { leave: visitor }). The class's methods are named after the kinds (FieldDefinition, NamedType, …), so a class instance works directly as a by-kind leave map.
• Types: visit is typed by graphql's ASTVisitor. oldVisit's visitor is now OldVisitor (this PR).

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