Add diagnostic API methods

[Copilot]

Adds getSyntacticDiagnostics, getSemanticDiagnostics, getSuggestionDiagnostics, getConfigFileParsingDiagnostics, and getDeclarationDiagnostics to the API surface.

Diagnostic API

• New method constants, proto params, and session handlers for each diagnostic kind
• Async Program methods that call through to the Go server, plus auto-generated sync variants
• Response type is Diagnostic directly (no intermediate wire type needed since the shapes are identical at runtime)
• reportsUnnecessary/reportsDeprecated use omitzero so false is omitted from JSON and the TS types remain optional booleans — only true is sent on the wire
• getGlobalDiagnostics is excluded for now due to a pre-existing checker pool type assertion issue in the compiler

Test helper: rangeOf

Tests use assert.deepEqual with exact expected values. A rangeOf(source, searchString, occurrence?) helper computes { pos, end } via indexOf, replacing opaque magic numbers with human-readable assertions:

const source = `interface Props { callback: (x: string) => void }
const p: Props = { callback: (x: number) => {} };`;

const declRange = rangeOf(source, "callback", 0);   // declaration site
const assignRange = rangeOf(source, "callback", 1);  // assignment site

assert.deepEqual(diags, [{
    fileName: "/src/index.ts",
    ...assignRange,
    code: 2322,
    category: DiagnosticCategory.Error,
    text: "Type '(x: number) => void' is not assignable to type '(x: string) => void'.",
    relatedInformation: [{ ...declRange, /* ... */ }],
}]);

occurrence is 0-based (default 0). One test per diagnostic method; the semantic test covers both messageChain and relatedInformation.

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[Copilot]

Pull request overview

Adds compiler diagnostic retrieval to the TypeScript-Go API surface, wiring new request methods through the Go session layer and exposing them via the @typescript/api Program (async + generated sync). Also introduces a small test helper to make diagnostic range assertions easier to read.

Changes:

• Add new diagnostic API methods (syntactic/semantic/suggestion/declaration/config parsing/global) to internal/api protocol + session handlers.
• Expose the new methods on _packages/api Program and add Diagnostic + DiagnosticCategory types.
• Add sync/async API tests for each diagnostic method and a rangeOf helper for { pos, end } assertions.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
internal/api/session.go	Adds request routing + handlers that call program.Get*Diagnostics(...), including optional-file resolution.
internal/api/proto.go	Adds method constants, params structs, and diagnostic response serialization (DiagnosticResponse).
_packages/api/src/async/api.ts	Adds async Program.get*Diagnostics methods and re-exports DiagnosticCategory.
_packages/api/src/async/types.ts	Introduces Diagnostic interface and imports DiagnosticCategory type.
_packages/api/src/sync/api.ts	Generated sync counterparts of the new Program.get*Diagnostics methods and exports.
_packages/api/src/sync/types.ts	Generated sync Diagnostic interface.
_packages/api/src/enums/diagnosticCategory.ts	Adds runtime enum module for DiagnosticCategory (generated).
_packages/api/src/enums/diagnosticCategory.enum.ts	Adds type enum module for DiagnosticCategory (generated).
_packages/api/test/async/api.test.ts	Adds async coverage for each diagnostics method + rangeOf helper.
_packages/api/test/sync/api.test.ts	Adds sync coverage for each diagnostics method + rangeOf helper.
Herebyfile.mjs	Registers DiagnosticCategory for enum generation into _packages/api/src/enums.

[andrewbranch]

@copilot address review feedback and format

[Copilot]

@copilot address review feedback and format

Removed omitempty from reportsUnnecessary/reportsDeprecated so false is always serialized, and ran the formatter. Fixed in e28d9f9.

Note: I kept the getGlobalDiagnostics test as a type check only because GetGlobalDiagnostics in internal/compiler/program.go:1164 does a hard type assertion p.checkerPool.(*checkerPool) that panics when the API uses the project-level checker pool. That's a pre-existing bug unrelated to this PR.

[andrewbranch]

@copilot just remove getGlobalDiagnostics from the API for now.

[Copilot]

@copilot just remove getGlobalDiagnostics from the API for now.

Removed getGlobalDiagnostics from the Go protocol, session handler, and TypeScript Program class, along with its tests in both async and sync suites. Fixed in ab2d911.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated no new comments.