Remove fanout hotspot from default pack (#25)

* Remove fanout hotspot from default pack

* Fix flaky benchmark history delta assertion

Author: benvinegar

README.md

@@ -141,7 +141,6 @@ Current checks focus on patterns that often show up in unreviewed generated code
 - [async wrapper / `return await` noise](src/rules/async-noise/README.md)
 - [pass-through wrappers](src/rules/pass-through-wrappers/README.md)
 - [duplicate helper/function signatures across source files](src/rules/duplicate-function-signatures/README.md)
-- [directory fan-out hotspots](src/rules/directory-fanout-hotspot/README.md)
 - [duplicated test mock/setup patterns](src/rules/duplicate-mock-setup/README.md)
 
 `scan` reports raw + normalized scores, hotspot tables, and grouped findings. Use `--json` when you want the full evidence payload.
@@ -240,7 +239,6 @@ The analyzer reads `slop-scan.config.ts`, `slop-scan.config.js`, `slop-scan.conf
     {
       "files": ["src/rules/**"],
       "rules": {
-        "structure.directory-fanout-hotspot": { "enabled": false },
         "structure.over-fragmentation": { "enabled": false }
       }
     }

src/default-registry.ts

@@ -20,7 +20,6 @@ import { promiseDefaultFallbacksRule } from "./rules/promise-default-fallbacks";
 import { genericStatusEnvelopesRule } from "./rules/generic-status-envelopes";
 import { genericRecordCastsRule } from "./rules/generic-record-casts";
 import { stringifiedUnknownErrorsRule } from "./rules/stringified-unknown-errors";
-import { directoryFanoutHotspotRule } from "./rules/directory-fanout-hotspot";
 import { duplicateFunctionSignaturesRule } from "./rules/duplicate-function-signatures";
 import { passThroughWrappersRule } from "./rules/pass-through-wrappers";
 import { duplicateMockSetupRule } from "./rules/duplicate-mock-setup";
@@ -49,7 +48,6 @@ export function createDefaultRegistry(): Registry {
   registry.registerRule(stringifiedUnknownErrorsRule);
   registry.registerRule(passThroughWrappersRule);
   registry.registerRule(duplicateFunctionSignaturesRule);
-  registry.registerRule(directoryFanoutHotspotRule);
   registry.registerRule(duplicateMockSetupRule);
 
   registry.registerReporter(textReporter);

tests/benchmark-history.test.ts

@@ -208,10 +208,10 @@ describe("benchmark history support", () => {
     expect(summary.repos.every((repo) => repo.series.length === 2)).toBe(true);
     expect(
       summary.repos.find((repo) => repo.id === "slop-heavy")?.deltaFromPrevious?.repoScore,
-    ).toBe(2);
-    expect(summary.repos.find((repo) => repo.id === "mixed")?.deltaFromPrevious?.repoScore).toBe(
-      -1,
-    );
+    ).toBeCloseTo(2, 6);
+    expect(
+      summary.repos.find((repo) => repo.id === "mixed")?.deltaFromPrevious?.repoScore,
+    ).toBeCloseTo(-1, 6);
     expect(
       summary.repos.find((repo) => repo.id === "slop-heavy")?.highest?.blendedVsPinnedBaseline,
     ).toBe(adjustedSlopHeavyWeekTwo.blended.vsPinnedBaseline);

tests/fixtures-regression.test.ts

@@ -28,19 +28,18 @@ describe("fixture regression suite", () => {
       createDefaultRegistry(),
     );
 
-    expect(result.repoScore).toBeCloseTo(10.8666666667, 6);
-    expect(result.findings).toHaveLength(4);
+    expect(result.repoScore).toBeCloseTo(7.7, 6);
+    expect(result.findings).toHaveLength(3);
     expect([...new Set(result.findings.map((finding) => finding.ruleId))].sort()).toEqual([
       "defensive.async-noise",
       "defensive.error-obscuring",
-      "structure.directory-fanout-hotspot",
       "structure.pass-through-wrappers",
     ]);
     expect(result.fileScores.map((score) => score.path)).toEqual([
       "src/service.ts",
       "src/error.ts",
     ]);
-    expect(result.directoryScores.map((score) => score.path)).toEqual(["src/fragments"]);
+    expect(result.directoryScores).toHaveLength(0);
   });
 
   test("mixed fixture localizes hotspots to the slop subtree", async () => {
@@ -50,9 +49,9 @@ describe("fixture regression suite", () => {
       createDefaultRegistry(),
     );
 
-    expect(result.repoScore).toBeCloseTo(9.7, 6);
+    expect(result.repoScore).toBeCloseTo(6.7, 6);
     expect(result.fileScores[0]?.path).toBe("src/slop/service.ts");
-    expect(result.directoryScores[0]?.path).toBe("src/slop");
+    expect(result.directoryScores).toHaveLength(0);
     expect(result.fileScores.every((score) => score.path.startsWith("src/slop/"))).toBe(true);
   });
 
@@ -68,9 +67,9 @@ describe("fixture regression suite", () => {
     expect(output.status).toBe(0);
 
     const report = JSON.parse(output.stdout);
-    expect(report.summary.repoScore).toBeCloseTo(10.8666666667, 6);
-    expect(report.summary.findingCount).toBe(4);
-    expect(report.directoryScores[0].path).toBe("src/fragments");
+    expect(report.summary.repoScore).toBeCloseTo(7.7, 6);
+    expect(report.summary.findingCount).toBe(3);
+    expect(report.directoryScores).toHaveLength(0);
     expect(report.fileScores[0].path).toBe("src/service.ts");
   });
 
@@ -88,11 +87,7 @@ describe("fixture regression suite", () => {
       "strong  Found 1 error-obscuring catch block  defensive.error-obscuring",
     );
     expect(output.stdout).toContain("  at src/error.ts:2:1");
-    expect(output.stdout).toContain(
-      "medium  Directory fan-out is a repo hotspot (7 files vs baseline 1.0)  structure.directory-fanout-hotspot",
-    );
-    expect(output.stdout).toContain("  at src/fragments:1:1");
-    expect(output.stdout).toContain("4 findings");
+    expect(output.stdout).toContain("3 findings");
     expect(output.stdout).not.toContain("slop-scan report");
   });
 

tests/heuristics.test.ts

@@ -98,10 +98,9 @@ describe("heuristic rule pack", () => {
     expect(ruleIds.has("defensive.stringified-unknown-errors")).toBe(true);
     expect(ruleIds.has("defensive.async-noise")).toBe(true);
     expect(ruleIds.has("structure.pass-through-wrappers")).toBe(true);
-    expect(ruleIds.has("structure.directory-fanout-hotspot")).toBe(true);
 
     expect(result.fileScores.some((score) => score.path === "src/service.ts")).toBe(true);
-    expect(result.directoryScores[0]?.path).toBe("src/fragments");
+    expect(result.directoryScores).toHaveLength(0);
     expect(result.repoScore).toBeGreaterThan(0);
   });