diff --git a/src/lib/preflight-helpers.ts b/src/lib/preflight-helpers.ts
new file mode 100644
index 0000000..8242634
--- /dev/null
+++ b/src/lib/preflight-helpers.ts
@@ -0,0 +1,102 @@
+/**
+ * Extracted helpers from preflight-check tool for testability.
+ */
+import { existsSync, statSync } from "fs";
+import { resolve } from "path";
+import { PROJECT_DIR } from "./files.js";
+
+// Common false positives that look like file paths but aren't
+const FALSE_POSITIVE_PATHS = new Set([
+  "e.g.", "i.e.", "etc.", "vs.", "v1", "v2", "v3", "v4", "v5",
+  "node.js", "next.js", "vue.js", "react.js", "express.js", "bun.js",
+]);
+
+// Version-like patterns: v1.2.3, 3.2.0, etc.
+const VERSION_PATTERN = /^v?\d+\.\d+(\.\d+)?$/;
+
+// Must contain a slash OR end with a real file extension
+const REAL_FILE_EXTENSIONS = new Set([
+  "ts", "tsx", "js", "jsx", "mjs", "cjs",
+  "json", "yaml", "yml", "toml", "md", "mdx",
+  "css", "scss", "less", "html", "vue", "svelte",
+  "py", "rb", "rs", "go", "java", "c", "cpp", "h",
+  "sh", "bash", "zsh", "fish",
+  "sql", "graphql", "gql", "prisma",
+  "env", "lock", "log", "txt", "csv",
+  "png", "jpg", "jpeg", "gif", "svg", "ico", "webp",
+  "wasm", "map", "d",
+]);
+
+/** Extract file paths from prompt text, filtering out false positives */
+export function extractFilePaths(prompt: string): string[] {
+  const matches = prompt.match(/[\w\-./\\]+\.\w{1,6}/g) || [];
+  return [...new Set(matches)].filter((m) => {
+    // Remove trailing punctuation that got captured
+    const clean = m.replace(/[.,;:!?)]+$/, "");
+    if (!clean.includes(".")) return false;
+
+    // Filter known false positives
+    const lower = clean.toLowerCase();
+    if (FALSE_POSITIVE_PATHS.has(lower)) return false;
+
+    // Filter version strings
+    if (VERSION_PATTERN.test(clean)) return false;
+
+    // Must have a slash (path separator) or a recognized extension
+    if (clean.includes("/") || clean.includes("\\")) return true;
+    const ext = clean.split(".").pop()?.toLowerCase() ?? "";
+    return REAL_FILE_EXTENSIONS.has(ext);
+  });
+}
+
+/** Verify files exist relative to PROJECT_DIR and return status lines */
+export function verifyFiles(paths: string[]): string[] {
+  const lines: string[] = [];
+  for (const p of paths) {
+    const abs = resolve(PROJECT_DIR, p);
+    if (!abs.startsWith(resolve(PROJECT_DIR))) continue; // path traversal guard
+    if (existsSync(abs)) {
+      const s = statSync(abs);
+      lines.push(`✅ \`${p}\` — ${s.size} bytes, modified ${s.mtime.toISOString().slice(0, 16)}`);
+    } else {
+      lines.push(`❌ \`${p}\` — not found`);
+    }
+  }
+  return lines;
+}
+
+/** Detect ambiguity signals in a prompt */
+export function detectAmbiguity(prompt: string): string[] {
+  const issues: string[] = [];
+  if (/\b(it|them|the thing|that|those|this|these)\b/i.test(prompt))
+    issues.push("Contains vague pronouns — clarify what 'it'/'them' refers to");
+  if (/\b(fix|update|change|refactor|improve)\b/i.test(prompt) && !extractFilePaths(prompt).length)
+    issues.push("Vague verb without specific file targets");
+  if (prompt.trim().length < 40)
+    issues.push("Very short prompt — likely missing context");
+  return issues;
+}
+
+/** Estimate scope complexity from file references */
+export function estimateComplexity(filePaths: string[]): "SMALL" | "MEDIUM" | "LARGE" {
+  const hasMultipleFiles = filePaths.length > 3;
+  const hasMultipleDirs = new Set(filePaths.map((f) => f.split("/")[0])).size > 2;
+  return hasMultipleFiles && hasMultipleDirs ? "LARGE" : filePaths.length > 1 ? "MEDIUM" : "SMALL";
+}
+
+/** Split prompt into sub-tasks for sequencing */
+export function splitSubtasks(prompt: string): { task: string; risk: string }[] {
+  const parts = prompt
+    .split(/\b(?:then|after that|next|finally)\b|(?:,\s*and\s+)|(?:\band\b(?=\s+(?:update|add|remove|create|fix|change|refactor|implement|deploy)))/i)
+    .map((s) => s.trim())
+    .filter((s) => s.length > 5);
+
+  return (parts.length > 1 ? parts : [prompt.slice(0, 100)]).map((part) => {
+    const risk = /schema|migrat|database|config|env|deploy/i.test(part)
+      ? "🔴 HIGH"
+      : /api|route|endpoint/i.test(part)
+        ? "🟡 MEDIUM"
+        : "🟢 LOW";
+    return { task: part.charAt(0).toUpperCase() + part.slice(1), risk };
+  });
+}
diff --git a/src/tools/preflight-check.ts b/src/tools/preflight-check.ts
index 8c9121a..97ead63 100644
--- a/src/tools/preflight-check.ts
+++ b/src/tools/preflight-check.ts
@@ -2,8 +2,7 @@
 import { z } from "zod";
 import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { triagePrompt, type TriageLevel, type TriageResult } from "../lib/triage.js";
-import { existsSync, statSync } from "fs";
-import { resolve } from "path";
+import { existsSync } from "fs";
 import { PROJECT_DIR } from "../lib/files.js";
 import { run, getBranch, getStatus, getRecentCommits, getDiffFiles, getStagedFiles } from "../lib/git.js";
 import { now } from "../lib/state.js";
@@ -13,32 +12,12 @@ import { searchSemantic } from "../lib/timeline-db.js";
 import { basename, join } from "path";
 import { loadPatterns, matchPatterns, formatPatternMatches } from "../lib/patterns.js";
 
+import { extractFilePaths, verifyFiles, detectAmbiguity, estimateComplexity, splitSubtasks } from "../lib/preflight-helpers.js";
+
 // ---------------------------------------------------------------------------
 // Helpers
 // ---------------------------------------------------------------------------
 
-/** Extract file paths from prompt text */
-function extractFilePaths(prompt: string): string[] {
-  const matches = prompt.match(/[\w\-./\\]+\.\w{1,6}/g) || [];
-  return [...new Set(matches)];
-}
-
-/** Verify files exist and return stats */
-function verifyFiles(paths: string[]): string[] {
-  const lines: string[] = [];
-  for (const p of paths) {
-    const abs = resolve(PROJECT_DIR, p);
-    if (!abs.startsWith(resolve(PROJECT_DIR))) continue; // path traversal guard
-    if (existsSync(abs)) {
-      const s = statSync(abs);
-      lines.push(`✅ \`${p}\` — ${s.size} bytes, modified ${s.mtime.toISOString().slice(0, 16)}`);
-    } else {
-      lines.push(`❌ \`${p}\` — not found`);
-    }
-  }
-  return lines;
-}
-
 /** Get related project paths from config + env */
 function getRelatedProjects(): { alias: string; path: string }[] {
   // From config
@@ -104,10 +83,7 @@ function buildClarifySection(prompt: string): string[] {
   }
 
   // Ambiguity signals
-  const issues: string[] = [];
-  if (/\b(it|them|the thing|that|those|this|these)\b/i.test(prompt)) issues.push("Contains vague pronouns — clarify what 'it'/'them' refers to");
-  if (/\b(fix|update|change|refactor|improve)\b/i.test(prompt) && !extractFilePaths(prompt).length) issues.push("Vague verb without specific file targets");
-  if (prompt.trim().length < 40) issues.push("Very short prompt — likely missing context");
+  const issues = detectAmbiguity(prompt);
 
   if (issues.length > 0) {
     sections.push(`### ⚠️ Clarification Needed\n${issues.map(i => `- ${i}`).join("\n")}`);
@@ -126,10 +102,7 @@ function buildScopeSection(prompt: string): string[] {
     sections.push(`### Referenced Files\n${fileVerification.join("\n")}`);
   }
 
-  // Estimate complexity
-  const hasMultipleFiles = filePaths.length > 3;
-  const hasMultipleDirs = new Set(filePaths.map(f => f.split("/")[0])).size > 2;
-  const complexity = hasMultipleFiles && hasMultipleDirs ? "LARGE" : filePaths.length > 1 ? "MEDIUM" : "SMALL";
+  const complexity = estimateComplexity(filePaths);
   sections.push(`### Scope: ${complexity}`);
 
   return sections;
@@ -137,28 +110,12 @@ function buildScopeSection(prompt: string): string[] {
 
 /** Build sequence section for multi-step */
 function buildSequenceSection(prompt: string): string[] {
-  // Split prompt into sub-tasks
-  const subtasks: string[] = [];
-
-  // Split on "and", "then", numbered lists, bullet points
-  const parts = prompt
-    .split(/\b(?:then|after that|next|finally)\b|(?:,\s*and\s+)|(?:\band\b(?=\s+(?:update|add|remove|create|fix|change|refactor|implement|deploy)))/i)
-    .map(s => s.trim())
-    .filter(s => s.length > 5);
-
-  if (parts.length > 1) {
-    for (let i = 0; i < parts.length; i++) {
-      const risk = /schema|migrat|database|config|env|deploy/i.test(parts[i]) ? "🔴 HIGH" :
-                   /api|route|endpoint/i.test(parts[i]) ? "🟡 MEDIUM" : "🟢 LOW";
-      subtasks.push(`${i + 1}. ${parts[i].charAt(0).toUpperCase() + parts[i].slice(1)} — Risk: ${risk}`);
-    }
-  } else {
-    subtasks.push(`1. ${prompt.slice(0, 100)} — Risk: 🟡 MEDIUM`);
-  }
+  const subtasks = splitSubtasks(prompt);
+  const lines = subtasks.map((s, i) => `${i + 1}. ${s.task} — Risk: ${s.risk}`);
 
   return [
     `### Execution Plan`,
-    ...subtasks,
+    ...lines,
     "",
     "### Checkpoints",
     "- [ ] Verify after each step before proceeding",
diff --git a/tests/lib/preflight-helpers.test.ts b/tests/lib/preflight-helpers.test.ts
new file mode 100644
index 0000000..bddac0a
--- /dev/null
+++ b/tests/lib/preflight-helpers.test.ts
@@ -0,0 +1,99 @@
+import { describe, it, expect } from "vitest";
+import { extractFilePaths, detectAmbiguity, estimateComplexity, splitSubtasks } from "../../src/lib/preflight-helpers.js";
+
+describe("extractFilePaths", () => {
+  it("extracts real file paths", () => {
+    expect(extractFilePaths("update src/lib/git.ts and tests/foo.test.ts")).toEqual([
+      "src/lib/git.ts",
+      "tests/foo.test.ts",
+    ]);
+  });
+
+  it("filters out version strings", () => {
+    expect(extractFilePaths("upgrade to v3.2.0")).toEqual([]);
+    expect(extractFilePaths("version 1.0.0 is out")).toEqual([]);
+  });
+
+  it("filters out common abbreviations", () => {
+    expect(extractFilePaths("e.g. this should work, i.e. correctly")).toEqual([]);
+  });
+
+  it("filters out framework names without path context", () => {
+    // node.js, next.js etc. are not file paths on their own
+    expect(extractFilePaths("use node.js for the backend")).toEqual([]);
+  });
+
+  it("keeps paths with slashes even without known extensions", () => {
+    expect(extractFilePaths("check config/app.conf")).toEqual(["config/app.conf"]);
+  });
+
+  it("deduplicates", () => {
+    expect(extractFilePaths("edit foo.ts and then foo.ts again")).toEqual(["foo.ts"]);
+  });
+
+  it("handles empty/no-match prompts", () => {
+    expect(extractFilePaths("just fix the bug")).toEqual([]);
+    expect(extractFilePaths("")).toEqual([]);
+  });
+});
+
+describe("detectAmbiguity", () => {
+  it("flags vague pronouns", () => {
+    const issues = detectAmbiguity("fix it and deploy");
+    expect(issues.some((i) => i.includes("vague pronouns"))).toBe(true);
+  });
+
+  it("flags vague verbs without file targets", () => {
+    const issues = detectAmbiguity("refactor the code to be cleaner");
+    expect(issues.some((i) => i.includes("Vague verb"))).toBe(true);
+  });
+
+  it("does not flag vague verbs when files are referenced", () => {
+    const issues = detectAmbiguity("refactor src/lib/git.ts to use async");
+    expect(issues.some((i) => i.includes("Vague verb"))).toBe(false);
+  });
+
+  it("flags short prompts", () => {
+    const issues = detectAmbiguity("fix bug");
+    expect(issues.some((i) => i.includes("Very short"))).toBe(true);
+  });
+
+  it("returns empty for clear prompts", () => {
+    const issues = detectAmbiguity("Add a new endpoint in src/routes/users.ts returning paginated user list with offset and limit params");
+    expect(issues).toEqual([]);
+  });
+});
+
+describe("estimateComplexity", () => {
+  it("returns SMALL for 0-1 files", () => {
+    expect(estimateComplexity([])).toBe("SMALL");
+    expect(estimateComplexity(["src/foo.ts"])).toBe("SMALL");
+  });
+
+  it("returns MEDIUM for 2-3 files", () => {
+    expect(estimateComplexity(["src/a.ts", "src/b.ts"])).toBe("MEDIUM");
+  });
+
+  it("returns LARGE for many files across dirs", () => {
+    expect(estimateComplexity(["src/a.ts", "tests/b.ts", "lib/c.ts", "docs/d.md"])).toBe("LARGE");
+  });
+});
+
+describe("splitSubtasks", () => {
+  it("splits on 'then'", () => {
+    const tasks = splitSubtasks("update the schema then run migrations then deploy");
+    expect(tasks.length).toBe(3);
+  });
+
+  it("assigns risk levels", () => {
+    const tasks = splitSubtasks("update the database schema then add an API endpoint then fix the button");
+    expect(tasks[0].risk).toBe("🔴 HIGH"); // database/schema
+    expect(tasks[1].risk).toBe("🟡 MEDIUM"); // API/endpoint
+    expect(tasks[2].risk).toBe("🟢 LOW");
+  });
+
+  it("returns single task for simple prompts", () => {
+    const tasks = splitSubtasks("add a login page");
+    expect(tasks.length).toBe(1);
+  });
+});