diff --git a/gitnexus/test/helpers/r-argument-scaling.ts b/gitnexus/test/helpers/r-argument-scaling.ts
new file mode 100644
index 000000000..f856dd931
--- /dev/null
+++ b/gitnexus/test/helpers/r-argument-scaling.ts
@@ -0,0 +1,96 @@
+/**
+ * Shared cost guard for the R argument-selection queries (the scope query and
+ * R_QUERIES). Both once had a quadratic formulation (an argument-prefix pattern
+ * repeated before the naming argument) that took seconds on one call with thousands
+ * of arguments.
+ *
+ * Absolute wall-clock limits are machine-dependent, so the guard compares the same
+ * work at two input sizes: linear work grows ~4x when the argument count is
+ * quadrupled, a quadratic query ~16x. Timings use the fastest of several runs and a
+ * floor on the small run, so scheduler noise on a loaded runner cannot inflate the
+ * ratio. Correctness of the output is asserted by the callers at both sizes, so an
+ * early return or an empty parse cannot pass as "fast".
+ */
+
+export const SMALL_N = 2000;
+export const LARGE_N = 8000;
+/** Linear is ~4; quadratic is ~16 or worse. */
+export const MAX_RATIO = 10;
+/** The small run is never treated as faster than this (below it, noise dominates). */
+const FLOOR_MS = 15;
+const REPEATS = 3;
+
+export interface ArgumentShape {
+  readonly name: string;
+  readonly build: (n: number) => string;
+}
+
+const named = (n: number) => Array.from({ length: n }, (_, k) => `a${k} = ${k}`).join(', ');
+const comments = (n: number) => Array.from({ length: n }, (_, k) => `# c${k}`).join('\n');
+const unnamedStrings = (n: number) => Array.from({ length: n }, (_, k) => `"s${k}"`).join(', ');
+const namedStrings = (n: number) =>
+  Array.from({ length: n }, (_, k) => `a${k} = "s${k}"`).join(', ');
+
+export const SHAPES = {
+  listNamedArguments: {
+    name: 'one call with many named arguments',
+    build: (n) => `x <- list(${named(n)})`,
+  },
+  setClassNamedBefore: {
+    name: 'setClass with many named arguments before the name',
+    build: (n) => `setClass(${named(n)}, "A")`,
+  },
+  libraryNamedBefore: {
+    name: 'library with many named arguments before the name',
+    build: (n) => `library(${named(n)}, pkg)`,
+  },
+  setClassCommentsBefore: {
+    name: 'setClass with many comments before the name',
+    build: (n) => `setClass(\n${comments(n)}\n"A")`,
+  },
+  libraryCommentsBefore: {
+    name: 'library with many comments before the name',
+    build: (n) => `library(\n${comments(n)}\npkg)`,
+  },
+  setClassUnnamedStrings: {
+    name: 'setClass with many unnamed arguments',
+    build: (n) => `setClass(${unnamedStrings(n)})`,
+  },
+  libraryUnnamedStrings: {
+    name: 'library with many unnamed arguments',
+    build: (n) => `library(${unnamedStrings(n)})`,
+  },
+  setClassNamedStrings: {
+    name: 'setClass with many named string arguments',
+    build: (n) => `setClass("A", ${namedStrings(n)})`,
+  },
+} as const satisfies Record<string, ArgumentShape>;
+
+/**
+ * Runs the work produced by `prepare(source)` at SMALL_N and LARGE_N and returns the
+ * results and the time ratio. `prepare` does the untimed set-up (e.g. parsing) and
+ * returns the thunk that is timed.
+ */
+export function measureScaling<T>(
+  prepare: (source: string) => () => T,
+  build: (n: number) => string,
+): { small: T; large: T; ratio: number } {
+  const run = (n: number) => {
+    const thunk = prepare(build(n));
+    let best = Infinity;
+    let result!: T;
+    for (let i = 0; i < REPEATS; i++) {
+      const start = performance.now();
+      result = thunk();
+      best = Math.min(best, performance.now() - start);
+    }
+    return { result, ms: best };
+  };
+  const small = run(SMALL_N);
+  const large = run(LARGE_N);
+  return {
+    small: small.result,
+    large: large.result,
+    ratio: large.ms / Math.max(small.ms, FLOOR_MS),
+  };
+}
diff --git a/gitnexus/test/unit/r-definition-anchors.test.ts b/gitnexus/test/unit/r-definition-anchors.test.ts
index 41ccdafc5..97d5b9fc3 100644
--- a/gitnexus/test/unit/r-definition-anchors.test.ts
+++ b/gitnexus/test/unit/r-definition-anchors.test.ts
@@ -15,6 +15,8 @@ import Parser from 'tree-sitter';
 import R from '@eagleoutice/tree-sitter-r';
 import { R_QUERIES } from '../../src/core/ingestion/tree-sitter-queries.js';
 import { isRNonNamingArgumentCapture } from '../../src/core/ingestion/languages/r/naming-argument.js';
+import { parseSourceSafe } from '../../src/core/tree-sitter/safe-parse.js';
+import { MAX_RATIO, SHAPES, measureScaling } from '../helpers/r-argument-scaling.js';
 
 const language = R as Parameters<Parser['setLanguage']>[0];
 const parser = new Parser();
@@ -23,10 +25,16 @@ const query = new Parser.Query(language, R_QUERIES);
 
 type Capture = { name: string; node: Parser.SyntaxNode };
 
+/**
+ * Parse like production does: `parseSourceSafe` avoids the native binding's crash on
+ * strings above 32 767 characters on Windows (the scaling group parses 100 K+ strings).
+ */
+const parseR = (source: string): Parser.Tree =>
+  parseSourceSafe(parser, source, undefined, { bufferSize: 1 << 24 });
+
 /** Matches the parse worker keeps: the provider's selection applied to the query's matches. */
 function keptMatches(source: string | Parser.Tree): Capture[][] {
-  const tree =
-    typeof source === 'string' ? parser.parse(source, undefined, { bufferSize: 1 << 24 }) : source;
+  const tree = typeof source === 'string' ? parseR(source) : source;
   const kept: Capture[][] = [];
   for (const match of query.matches(tree.rootNode)) {
     const captureMap: Record<string, Parser.SyntaxNode> = {};
@@ -273,45 +281,42 @@ describe('R naming argument: a later Class = retracts an earlier unnamed argumen
 /**
  * Selecting the naming argument must stay linear in the argument count: an earlier
  * query-level formulation (a repeated sibling group before the argument) was
- * quadratic and took seconds on a single call with thousands of arguments. The
- * bound is generous (a linear pass takes tens of milliseconds); the quadratic
- * shapes took 4s to 18s.
+ * quadratic and took seconds on a single call with thousands of arguments. The same
+ * work is run at two sizes and the time ratio is bounded (see
+ * `helpers/r-argument-scaling.ts`); the kept matches are asserted at both sizes.
  */
 describe('R_QUERIES: cost is linear in the argument count', () => {
-  const LIMIT_MS = 2500;
-  const N = 16000;
-  const named = (n: number) => Array.from({ length: n }, (_, k) => `a${k} = ${k}`).join(', ');
-  const timed = (source: string) => {
-    const tree = parser.parse(source, undefined, { bufferSize: 1 << 24 });
-    const start = Date.now();
-    const kept = keptMatches(tree).length;
-    return { ms: Date.now() - start, kept };
+  /** Parsing is set-up (untimed); the timed work is the query plus the provider's selection. */
+  const run = (source: string) => {
+    const tree = parseR(source);
+    return () => {
+      const kept = keptMatches(tree);
+      const defs: string[] = [];
+      for (const captures of kept) {
+        const def = captures.find((c) => c.name.startsWith('definition.'));
+        const name = captures.find((c) => c.name === 'name');
+        if (def && name) defs.push(`${def.name}:${name.node.text}`);
+      }
+      return { count: kept.length, defs };
+    };
   };
 
-  it('one call with many named arguments', () => {
-    expect(timed(`x <- list(${named(N)})`).ms).toBeLessThan(LIMIT_MS);
-  });
+  const cases = [
+    { shape: SHAPES.listNamedArguments, expected: { count: 1, defs: [] } },
+    { shape: SHAPES.setClassNamedBefore, expected: { count: 2, defs: ['definition.class:A'] } },
+    { shape: SHAPES.setClassCommentsBefore, expected: { count: 2, defs: ['definition.class:A'] } },
+    { shape: SHAPES.setClassUnnamedStrings, expected: { count: 2, defs: ['definition.class:s0'] } },
+    { shape: SHAPES.setClassNamedStrings, expected: { count: 2, defs: ['definition.class:A'] } },
+  ] as const;
 
-  it('setClass with many named arguments before the name', () => {
-    const { ms, kept } = timed(`setClass(${named(N / 2)}, "A")`);
-    expect(ms).toBeLessThan(LIMIT_MS);
-    expect(kept).toBeGreaterThan(0);
-  });
-
-  it('setClass with many comments before the name', () => {
-    const comments = Array.from({ length: N / 2 }, (_, k) => `# c${k}`).join('\n');
-    const { ms, kept } = timed(`setClass(\n${comments}\n"A")`);
-    expect(ms).toBeLessThan(LIMIT_MS);
-    expect(kept).toBeGreaterThan(0);
-  });
-
-  it('setClass with many unnamed string arguments', () => {
-    const strings = Array.from({ length: N }, (_, k) => `"s${k}"`).join(', ');
-    expect(timed(`setClass(${strings})`).ms).toBeLessThan(LIMIT_MS);
-  });
-
-  it('setClass with many named string arguments', () => {
-    const strings = Array.from({ length: N }, (_, k) => `a${k} = "s${k}"`).join(', ');
-    expect(timed(`setClass("A", ${strings})`).ms).toBeLessThan(LIMIT_MS);
-  });
+  it.each(cases)(
+    '$shape.name',
+    ({ shape, expected }) => {
+      const { small, large, ratio } = measureScaling(run, shape.build);
+      expect(small).toEqual(expected);
+      expect(large).toEqual(expected);
+      expect(ratio).toBeLessThan(MAX_RATIO);
+    },
+    120_000,
+  );
 });
diff --git a/gitnexus/test/unit/r-scope-naming-argument.test.ts b/gitnexus/test/unit/r-scope-naming-argument.test.ts
index 74228eaaf..8368bba10 100644
--- a/gitnexus/test/unit/r-scope-naming-argument.test.ts
+++ b/gitnexus/test/unit/r-scope-naming-argument.test.ts
@@ -2,12 +2,13 @@
  * R scope query: only the argument that names a class or an import yields
  * `@declaration.name` / `@import.source`. The query captures every candidate
  * argument; `emitRScopeCaptures` drops the rest. Each negative is paired with a
- * positive control, and a bounded-time group guards the cost against a quadratic
+ * positive control, and a scaling group guards the cost against a quadratic
  * regression (an argument-prefix pattern in the query was quadratic in the number
  * of leading comments and named arguments).
  */
 import { describe, expect, it } from 'vitest';
 import { emitRScopeCaptures } from '../../src/core/ingestion/languages/r/captures.js';
+import { MAX_RATIO, SHAPES, measureScaling } from '../helpers/r-argument-scaling.js';
 
 function tagTexts(source: string, tag: string): string[] {
   return emitRScopeCaptures(source, 'fixture.R')
@@ -16,8 +17,16 @@ function tagTexts(source: string, tag: string): string[] {
 }
 
 const importSources = (source: string) => tagTexts(source, '@import.source');
+/**
+ * Every class declared by the scope query. Selected by capture kind (the match carries
+ * `@declaration.class`), not by spelling, so a lowercase class or a wrongly captured
+ * lowercase string is visible.
+ */
 const classNames = (source: string) =>
-  tagTexts(source, '@declaration.name').filter((t) => /^[A-Z]/.test(t));
+  emitRScopeCaptures(source, 'fixture.R')
+    .filter((m) => m['@declaration.class'] !== undefined)
+    .map((m) => m['@declaration.name']?.text)
+    .filter((t): t is string => t !== undefined);
 
 describe('R scope query: imports name only their first argument', () => {
   it('imports the first argument (positive controls)', () => {
@@ -61,6 +70,19 @@ describe('R scope query: setClass declares only its naming argument', () => {
     expect(classNames('setRefClass("R", contains = "Base")')).toEqual(['R']);
   });
 
+  it('declares a lowercase class name (positive controls)', () => {
+    expect(classNames('setClass("a", contains = "VIRTUAL")')).toEqual(['a']);
+    expect(classNames('setRefClass("r")')).toEqual(['r']);
+    expect(classNames('setClass(Class = "a")')).toEqual(['a']);
+  });
+
+  it('does not declare a lowercase class from a non-naming argument', () => {
+    expect(classNames('setClass("A", contains = "numeric")')).toEqual(['A']);
+    expect(classNames('setRefClass("R", contains = "base")')).toEqual(['R']);
+    expect(classNames('setClass("a", contains = "numeric", package = "pkg")')).toEqual(['a']);
+    expect(classNames('setClass("A", representation("numeric", x = "character"))')).toEqual(['A']);
+  });
+
   it('declares only Class = when it follows an unnamed argument', () => {
     expect(classNames('setClass(a = "Q", "B", Class = "A")')).toEqual(['A']);
     expect(classNames('setRefClass("B", Class = "A")')).toEqual(['A']);
@@ -79,33 +101,49 @@ describe('R scope query: setClass declares only its naming argument', () => {
 });
 
 describe('R scope query: cost is linear in the argument count', () => {
-  const LIMIT_MS = 2500;
-  const N = 16000;
-  const named = (n: number) => Array.from({ length: n }, (_, k) => `a${k} = ${k}`).join(', ');
-  const timed = (source: string) => {
-    const start = Date.now();
-    const matches = emitRScopeCaptures(source, 'fixture.R').length;
-    return { ms: Date.now() - start, matches };
+  /** What the query kept: the match count and the naming captures, in source order. */
+  const run = (source: string) => () => {
+    const matches = emitRScopeCaptures(source, 'fixture.R');
+    const naming: string[] = [];
+    for (const m of matches) {
+      for (const tag of ['@declaration.name', '@import.source']) {
+        const text = m[tag]?.text;
+        if (text !== undefined) naming.push(`${tag}=${text}`);
+      }
+    }
+    return { count: matches.length, naming };
   };
 
-  it('one call with many named arguments', () => {
-    expect(timed(`x <- list(${named(N)})`).ms).toBeLessThan(LIMIT_MS);
-  });
+  // Every shape keeps exactly one naming capture regardless of the argument count: the
+  // count and the name are asserted at both sizes, so an early-return or empty parse
+  // cannot pass as "fast".
+  const cases = [
+    { shape: SHAPES.listNamedArguments, expected: { count: 2, naming: [] } },
+    { shape: SHAPES.setClassNamedBefore, expected: { count: 4, naming: ['@declaration.name=A'] } },
+    { shape: SHAPES.libraryNamedBefore, expected: { count: 3, naming: ['@import.source=pkg'] } },
+    {
+      shape: SHAPES.setClassCommentsBefore,
+      expected: { count: 4, naming: ['@declaration.name=A'] },
+    },
+    { shape: SHAPES.libraryCommentsBefore, expected: { count: 3, naming: ['@import.source=pkg'] } },
+    {
+      shape: SHAPES.setClassUnnamedStrings,
+      expected: { count: 4, naming: ['@declaration.name=s0'] },
+    },
+    {
+      shape: SHAPES.libraryUnnamedStrings,
+      expected: { count: 3, naming: ['@import.source="s0"'] },
+    },
+  ] as const;
 
-  it('setClass and library with many named arguments before the name', () => {
-    expect(timed(`setClass(${named(N / 2)}, "A")`).ms).toBeLessThan(LIMIT_MS);
-    expect(timed(`library(${named(N / 2)}, pkg)`).ms).toBeLessThan(LIMIT_MS);
-  });
-
-  it('setClass and library with many comments before the name', () => {
-    const comments = Array.from({ length: N / 2 }, (_, k) => `# c${k}`).join('\n');
-    expect(timed(`setClass(\n${comments}\n"A")`).ms).toBeLessThan(LIMIT_MS);
-    expect(timed(`library(\n${comments}\npkg)`).ms).toBeLessThan(LIMIT_MS);
-  });
-
-  it('setClass and library with many unnamed arguments', () => {
-    const strings = Array.from({ length: N }, (_, k) => `"s${k}"`).join(', ');
-    expect(timed(`setClass(${strings})`).ms).toBeLessThan(LIMIT_MS);
-    expect(timed(`library(${strings})`).ms).toBeLessThan(LIMIT_MS);
-  });
+  it.each(cases)(
+    '$shape.name',
+    ({ shape, expected }) => {
+      const { small, large, ratio } = measureScaling(run, shape.build);
+      expect(small).toEqual(expected);
+      expect(large).toEqual(expected);
+      expect(ratio).toBeLessThan(MAX_RATIO);
+    },
+    120_000,
+  );
 });