diff --git a/lib/project-facts.js b/lib/project-facts.js
index 871c5be..13b970f 100644
--- a/lib/project-facts.js
+++ b/lib/project-facts.js
@@ -357,6 +357,101 @@ function getFrameworkSignals(rootDir) {
     return signals;
 }
 
+// Directory-name conventions checked by getArchitectureSignals(). Kept as
+// data, not inline logic, so the rule table stays legible against
+// adr-architecture-pattern-signals.md's own table.
+const MVC_DIR_NAMES = ["controllers", "models", "views"];
+const LAYERED_DIR_NAME_GROUPS = [
+    ["routes", "services", "repositories"],
+    ["domain", "application", "infrastructure"],
+];
+
+/**
+ * Collect every directory name appearing anywhere in a
+ * `getProjectStructure()` result (including nested `children`,
+ * recursively) into a Set. Reused by getArchitectureSignals() instead of
+ * a second filesystem walk.
+ * @param {object[]} structure
+ * @returns {Set<string>}
+ */
+function collectDirectoryNamesFromStructure(structure) {
+    const names = new Set();
+    (structure || []).forEach(function (node) {
+        names.add(node.name);
+        if (node.children) {
+            collectDirectoryNamesFromStructure(node.children).forEach(function (n) { names.add(n); });
+        }
+    });
+    return names;
+}
+
+/**
+ * Architecture-pattern signals: independent, evidence-backed
+ * observations (never a single forced "the architecture is X" label --
+ * see adr-architecture-pattern-signals.md). Every rule is deterministic
+ * and reuses Phase 1 (`getProjectStructure`, `getWorkspacePackages`) and
+ * Phase 2 (`getFrameworkSignals`) output -- zero new filesystem calls.
+ * @param {string} rootDir
+ * @returns {{name: string, evidence: string}[]}
+ */
+function getArchitectureSignals(rootDir) {
+    const signals = [];
+    const pkg = readJsonSafe(path.join(rootDir, "package.json"), {});
+
+    if (pkg.bin && (typeof pkg.bin === "string" || (typeof pkg.bin === "object" && Object.keys(pkg.bin).length > 0))) {
+        const binNames = typeof pkg.bin === "string" ? [path.basename(rootDir)] : Object.keys(pkg.bin);
+        signals.push({ name: "CLI tool", evidence: "package.json \"bin\": " + binNames.join(", ") });
+    }
+
+    if (pkg.main || pkg.exports) {
+        signals.push({ name: "Publishable library", evidence: "package.json has a \"" + (pkg.exports ? "exports" : "main") + "\" field" });
+    }
+
+    const workspacePackages = getWorkspacePackages(rootDir);
+    if (workspacePackages.length > 0) {
+        signals.push({
+            name: "Monorepo (npm workspaces)",
+            evidence: workspacePackages.length + " workspace package(s): " + workspacePackages.map(function (p) { return p.name; }).join(", "),
+        });
+    }
+
+    const dependencyFrameworks = getFrameworkSignals(rootDir).filter(function (s) { return s.confidence === "dependency"; });
+    const dependencyNames = dependencyFrameworks.map(function (s) { return s.name; });
+
+    const backendFrameworks = dependencyNames.filter(function (n) { return n === "Express" || n === "NestJS"; });
+    if (backendFrameworks.length > 0) {
+        signals.push({ name: "Backend/API service", evidence: "framework dependency: " + backendFrameworks.join(", ") });
+    }
+
+    const frontendFrameworks = dependencyNames.filter(function (n) { return ["React", "Next.js", "Angular", "Vue"].indexOf(n) !== -1; });
+    if (frontendFrameworks.length > 0) {
+        signals.push({ name: "Frontend application", evidence: "framework dependency: " + frontendFrameworks.join(", ") });
+    }
+
+    const dirNames = collectDirectoryNamesFromStructure(getProjectStructure(rootDir));
+
+    const matchedMvc = MVC_DIR_NAMES.filter(function (n) { return dirNames.has(n); });
+    if (matchedMvc.length >= 2) {
+        signals.push({ name: "MVC-influenced layout", evidence: "directories present: " + matchedMvc.join(", ") });
+    }
+
+    // One signal, not one per group: the rule is "group A matches OR
+    // group B matches", not two independent observations. If both
+    // groups happen to match, report both as evidence on the single
+    // signal rather than emitting a duplicate-named entry.
+    const matchedLayeredGroups = LAYERED_DIR_NAME_GROUPS
+        .map(function (group) { return group.filter(function (n) { return dirNames.has(n); }); })
+        .filter(function (matched) { return matched.length >= 2; });
+    if (matchedLayeredGroups.length > 0) {
+        signals.push({
+            name: "Layered/service-oriented layout",
+            evidence: "directories present: " + matchedLayeredGroups.map(function (g) { return g.join(", "); }).join(" / "),
+        });
+    }
+
+    return signals;
+}
+
 /**
  * Test-tooling facts: no framework, hand-rolled runner, no HTTP API.
  * @param {string} rootDir
@@ -393,6 +488,7 @@ function getAllFacts(rootDir) {
         structure: getProjectStructure(dir),
         workspacePackages: getWorkspacePackages(dir),
         frameworkSignals: getFrameworkSignals(dir),
+        architectureSignals: getArchitectureSignals(dir),
         test: getTestInfo(dir),
     };
 }
@@ -404,6 +500,7 @@ module.exports = {
     getProjectStructure,
     getWorkspacePackages,
     getFrameworkSignals,
+    getArchitectureSignals,
     getTestInfo,
     getAllFacts,
 };
diff --git a/test/project-facts.test.js b/test/project-facts.test.js
index a9ba334..b694331 100644
--- a/test/project-facts.test.js
+++ b/test/project-facts.test.js
@@ -18,6 +18,7 @@ const {
     getProjectStructure,
     getWorkspacePackages,
     getFrameworkSignals,
+    getArchitectureSignals,
     getTestInfo,
     getAllFacts,
 } = require("../lib/project-facts.js");
@@ -268,6 +269,123 @@ module.exports = function runProjectFactsTests(check) {
         ]);
     });
 
+    check("getArchitectureSignals: detects 'CLI tool' from a non-empty package.json bin field", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({ bin: { "my-cli": "./bin/cli.js" } }));
+        const signals = getArchitectureSignals(dir);
+        assert.strictEqual(signals.length, 1);
+        assert.strictEqual(signals[0].name, "CLI tool");
+        assert.match(signals[0].evidence, /my-cli/);
+    });
+
+    check("getArchitectureSignals: detects 'Publishable library' from main/exports, preferring exports in the evidence text", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({ main: "index.js", exports: { ".": "./index.js" } }));
+        const signals = getArchitectureSignals(dir);
+        assert.strictEqual(signals.length, 1);
+        assert.strictEqual(signals[0].name, "Publishable library");
+        assert.match(signals[0].evidence, /"exports"/);
+    });
+
+    check("getArchitectureSignals: detects 'Monorepo (npm workspaces)' and names the resolved packages in evidence", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({ workspaces: ["packages/*"] }));
+        fs.mkdirSync(path.join(dir, "packages", "pkg-a"), { recursive: true });
+        fs.writeFileSync(path.join(dir, "packages", "pkg-a", "package.json"), JSON.stringify({ name: "pkg-a" }));
+        const signals = getArchitectureSignals(dir);
+        assert.strictEqual(signals.length, 1);
+        assert.strictEqual(signals[0].name, "Monorepo (npm workspaces)");
+        assert.match(signals[0].evidence, /pkg-a/);
+    });
+
+    check("getArchitectureSignals: detects 'Backend/API service' only from a dependency-confidence framework signal", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({ dependencies: { express: "^4.0.0" } }));
+        const signals = getArchitectureSignals(dir);
+        assert.strictEqual(signals.length, 1);
+        assert.strictEqual(signals[0].name, "Backend/API service");
+    });
+
+    check("getArchitectureSignals: 'Backend/API service' does NOT fire from a file-heuristic-only framework signal", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({}));
+        fs.mkdirSync(path.join(dir, "src"));
+        fs.writeFileSync(path.join(dir, "src", "App.jsx"), ""); // file-heuristic React only, no dependency
+        const signals = getArchitectureSignals(dir);
+        assert.ok(!signals.some((s) => s.name === "Frontend application"), "file-heuristic-only signals must not promote to an architecture claim");
+    });
+
+    check("getArchitectureSignals: detects 'MVC-influenced layout' when at least 2 of controllers/models/views exist", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({}));
+        fs.mkdirSync(path.join(dir, "src", "controllers"), { recursive: true });
+        fs.mkdirSync(path.join(dir, "src", "models"), { recursive: true });
+        const signals = getArchitectureSignals(dir);
+        assert.strictEqual(signals.length, 1);
+        assert.strictEqual(signals[0].name, "MVC-influenced layout");
+        assert.match(signals[0].evidence, /controllers/);
+        assert.match(signals[0].evidence, /models/);
+    });
+
+    check("getArchitectureSignals: does NOT fire MVC on just 1 matching directory name", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({}));
+        fs.mkdirSync(path.join(dir, "src", "controllers"), { recursive: true });
+        assert.deepStrictEqual(getArchitectureSignals(dir), []);
+    });
+
+    check("getArchitectureSignals: detects 'Layered/service-oriented layout' from either directory-name group, reported as one signal even if both groups match", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({}));
+        fs.mkdirSync(path.join(dir, "src", "routes"), { recursive: true });
+        fs.mkdirSync(path.join(dir, "src", "services"), { recursive: true });
+        fs.mkdirSync(path.join(dir, "src", "domain"), { recursive: true });
+        fs.mkdirSync(path.join(dir, "src", "application"), { recursive: true });
+        const signals = getArchitectureSignals(dir);
+        assert.strictEqual(signals.length, 1, "both matching groups should still produce exactly one 'Layered/service-oriented layout' signal, not two");
+        assert.strictEqual(signals[0].name, "Layered/service-oriented layout");
+        assert.match(signals[0].evidence, /routes/);
+        assert.match(signals[0].evidence, /domain/);
+    });
+
+    check("getArchitectureSignals: multiple independent signals co-occur on one fixture (never collapsed into a single label)", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({ bin: { cli: "./bin/cli.js" }, main: "index.js", dependencies: { "@nestjs/core": "^10.0.0" } }));
+        fs.mkdirSync(path.join(dir, "src", "controllers"), { recursive: true });
+        fs.mkdirSync(path.join(dir, "src", "models"), { recursive: true });
+        const signals = getArchitectureSignals(dir);
+        const names = signals.map((s) => s.name).sort();
+        assert.deepStrictEqual(names, ["Backend/API service", "CLI tool", "MVC-influenced layout", "Publishable library"]);
+    });
+
+    check("getArchitectureSignals: returns an empty array on a plain repo with none of the 7 signals", () => {
+        const dir = tmpRepo();
+        fs.writeFileSync(path.join(dir, "package.json"), JSON.stringify({ dependencies: { lodash: "^4.0.0" } }));
+        fs.mkdirSync(path.join(dir, "lib"));
+        assert.deepStrictEqual(getArchitectureSignals(dir), []);
+    });
+
+    check("getArchitectureSignals: this repo's own real signals report CLI tool + Publishable library + Monorepo + Layered/service-oriented layout", () => {
+        // Verified against this repo's actual real directory tree (`find .
+        // -mindepth 1 -maxdepth 3 -type d`) before writing this assertion,
+        // not assumed: root package.json has both bin.gen-comments/
+        // bin.gen-docs and exports, one real npm workspace
+        // (eslint-plugin-jsdoc-scribe), and sample/express/ genuinely has
+        // both routes/ and services/ directories (fixture data, but the
+        // detector has no way to know that -- and per the ADR it
+        // shouldn't guess intent, only report what it found). No MVC
+        // signal (only controllers/ exists, not 2 of the 3 names), no
+        // Backend/API service or Frontend application (no framework
+        // dependency at confidence: "dependency" anywhere in this repo).
+        const signals = getArchitectureSignals(path.resolve(__dirname, ".."));
+        assert.deepStrictEqual(signals, [
+            { name: "CLI tool", evidence: "package.json \"bin\": gen-comments, gen-docs" },
+            { name: "Publishable library", evidence: "package.json has a \"exports\" field" },
+            { name: "Monorepo (npm workspaces)", evidence: "1 workspace package(s): eslint-plugin-jsdoc-scribe" },
+            { name: "Layered/service-oriented layout", evidence: "directories present: routes, services" },
+        ]);
+    });
+
     check("getTestInfo: reports no framework and no HTTP API", () => {
         const facts = getTestInfo(tmpRepo());
         assert.strictEqual(facts.framework, null);
@@ -291,6 +409,7 @@ module.exports = function runProjectFactsTests(check) {
         assert.ok("structure" in facts);
         assert.ok("workspacePackages" in facts);
         assert.ok("frameworkSignals" in facts);
+        assert.ok("architectureSignals" in facts);
         assert.ok("test" in facts);
     });
 };