Fix various bugs and allow api keyword

packages/pyright-internal/src/analyzer/typePrinter.ts

@@ -1118,6 +1118,9 @@ function printTypeWithCythonDetails(type: Type, objName: string) {
         if (details.isPublic) {
             prefixes.push('public');
         }
+        if (details.isApi) {
+            prefixes.push('api');
+        }
         if (details.isConst) {
             prefixes.push('const');
         }

packages/pyright-internal/src/analyzer/types.ts

@@ -299,6 +299,7 @@ export namespace TypeBase {
             isConst: node ? CTypeNode.isConstant(node) : false,
             isVolatile: node ? CTypeNode.isVolatile(node) : false,
             isPublic: node ? CTypeNode.isPublic(node) : false,
+            isApi: node ? CTypeNode.isApi(node) : false,
             isReadOnly: node ? CTypeNode.isReadOnly(node) : false,
             numMods: node ? CTypeNode.numModifiers(node) : [],
             trailType: node ? CTypeNode.trailType(node) : CTrailType.None,
@@ -606,6 +607,7 @@ export interface CythonDetails {
     isVolatile?: boolean;
     isReadOnly?: boolean;
     isPublic?: boolean;
+    isApi?: boolean;
     numMods?: string[]; // Numeric modifiers
     trailType?: CTrailType;
 

packages/pyright-internal/src/common/configOptions.ts

@@ -500,6 +500,17 @@ export function getOffDiagnosticRuleSet(): DiagnosticRuleSet {
     return diagSettings;
 }
 
+/** Cython: minimal diagnostics — only syntax/parse errors. Suppresses import and undefined-variable noise for .pyx/.pxd. */
+export function getCythonDiagnosticRuleSet(): DiagnosticRuleSet {
+    const diagSettings: DiagnosticRuleSet = {
+        ...getOffDiagnosticRuleSet(),
+        reportMissingImports: 'none',
+        reportMissingModuleSource: 'none',
+        reportUndefinedVariable: 'none',
+    };
+    return diagSettings;
+}
+
 export function getBasicDiagnosticRuleSet(): DiagnosticRuleSet {
     const diagSettings: DiagnosticRuleSet = {
         printUnknownAsAny: false,
@@ -818,6 +829,10 @@ export class ConfigOptions {
             return getOffDiagnosticRuleSet();
         }
 
+        if (typeCheckingMode === 'cython') {
+            return getCythonDiagnosticRuleSet();
+        }
+
         return getBasicDiagnosticRuleSet();
     }
 

packages/pyright-internal/src/languageService/completionProvider.ts

@@ -174,6 +174,7 @@ namespace Keywords {
         'const',
         'readonly',
         'public',
+        'api',
         'signed',
         'unsigned',
         'long',

packages/pyright-internal/src/parser/parseNodes.ts

@@ -2572,6 +2572,10 @@ export namespace CTypeNode {
         return hasModifier(node, KeywordType.Public);
     }
 
+    export function isApi(node: CTypeNode) {
+        return hasModifier(node, KeywordType.Api);
+    }
+
     export function isReadOnly(node: CTypeNode) {
         return hasModifier(node, KeywordType.Readonly);
     }

packages/pyright-internal/src/parser/tokenizer.ts

@@ -102,6 +102,7 @@ const _keywords: Map<string, KeywordType> = new Map([
     ['const', KeywordType.Const],
     ['readonly', KeywordType.Readonly],
     ['public', KeywordType.Public],
+    ['api', KeywordType.Api],
     ['signed', KeywordType.Signed],
     ['unsigned', KeywordType.Unsigned],
     ['long', KeywordType.Long],

packages/pyright-internal/src/parser/tokenizerTypes.ts

@@ -167,6 +167,7 @@ export const enum KeywordType {
     Const,
     Readonly,
     Public,
+    Api,
     Signed,
     Unsigned,
     Long,
@@ -196,6 +197,7 @@ export const varModifiers = [
     KeywordType.Readonly,
     KeywordType.Inline,
     KeywordType.Public,
+    KeywordType.Api,
     KeywordType.Volatile,
 ];
 
@@ -218,6 +220,7 @@ export const softKeywords = [
     KeywordType.Const,
     KeywordType.Readonly,
     KeywordType.Public,
+    KeywordType.Api,
     KeywordType.Signed,
     KeywordType.Unsigned,
     KeywordType.Long,

packages/pyright-internal/src/server.ts

@@ -226,7 +226,14 @@ export class PyrightServer extends LanguageServerBase {
                     });
                     serverSettings.includePaths = cythonPaths;
                 }
+                if (cythonSection.typeCheckingMode !== undefined && isString(cythonSection.typeCheckingMode)) {
+                    serverSettings.typeCheckingMode = cythonSection.typeCheckingMode;
+                }
             }
+
+            // ! Cython: use minimal diagnostics for .pyx/.pxd to avoid false positives
+            // (missing imports, undefined vars from cimports/C types). Set cython.typeCheckingMode to override.
+            serverSettings.typeCheckingMode = serverSettings.typeCheckingMode ?? 'cython';
         } catch (error) {
             this.console.error(`Error reading settings: ${error}`);
         }