diff --git a/.gitignore b/.gitignore
index cc9b2ff..9193168 100644
--- a/.gitignore
+++ b/.gitignore
@@ -54,3 +54,4 @@ skills-lock.json
 # Local experiment scratch (cloned tools / benchmark output, not part of the project)
 /aider/
 /tmp.benchmarks/
+modlane.yaml
diff --git a/openspec/changes/P9-env-support/proposal.md b/openspec/changes/P9-env-support/proposal.md
new file mode 100644
index 0000000..d21eb6d
--- /dev/null
+++ b/openspec/changes/P9-env-support/proposal.md
@@ -0,0 +1,14 @@
+# P9 — Local .env File Support
+
+## Why
+Instead of forcing developers to manually `export` their API keys in their console session before starting Modlane, we want to allow storing them in a local, gitignored `.env` file that loads automatically at startup.
+
+## What changes
+- `src/cli.ts`: Injected environment variable loading on startup. Uses `process.loadEnvFile()` natively (Node 20.12+) or a custom line-by-line fallback parser for older Node versions.
+- `src/env.test.ts` [NEW]: Unit tests covering the fallback parser logic (quotes, spacing, comments).
+
+## Impact
+Improves developer UX significantly, removing the need for console environment setup while keeping keys safely gitignored.
+
+## Status
+Done — implemented, fully tested, and compiling.
diff --git a/openspec/changes/P9-env-support/tasks.md b/openspec/changes/P9-env-support/tasks.md
new file mode 100644
index 0000000..6fa54bc
--- /dev/null
+++ b/openspec/changes/P9-env-support/tasks.md
@@ -0,0 +1,7 @@
+# P9 — Tasks
+
+- [x] Verify `.env` is ignored in `.gitignore`.
+- [x] Add `.env` file loading logic at the startup of `src/cli.ts`.
+- [x] Implement fallback parser to support Node.js versions < 20.12.
+- [x] Add unit tests in `src/env.test.ts` to test parser accuracy.
+- [x] Verify project builds and passes Vitest checks.
diff --git a/src/cli.ts b/src/cli.ts
index 9483257..d2093fa 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -1,7 +1,11 @@
 #!/usr/bin/env node
 import { ConfigError, loadConfig } from "./config.js";
+import { loadDotEnv } from "./env.js";
 import { startGateway } from "./server.js";
 
+// Load local environment variables from .env before anything reads process.env.
+loadDotEnv();
+
 const VERSION = "0.0.1";
 
 function usage(): void {
diff --git a/src/env.test.ts b/src/env.test.ts
new file mode 100644
index 0000000..a5b1ac1
--- /dev/null
+++ b/src/env.test.ts
@@ -0,0 +1,33 @@
+import { expect, test } from "vitest";
+import { parseEnv } from "./env.js";
+
+test("parses standard key-value pairs", () => {
+  const res = parseEnv("TEST_KEY=my-value");
+  expect(res.TEST_KEY).toBe("my-value");
+});
+
+test("ignores comments and empty lines", () => {
+  const res = parseEnv(`
+    # This is a comment
+    TEST_KEY=my-value
+
+    # Another comment
+    ANOTHER_KEY=value2
+  `);
+  expect(res.TEST_KEY).toBe("my-value");
+  expect(res.ANOTHER_KEY).toBe("value2");
+});
+
+test("handles single and double quotes", () => {
+  const res = parseEnv(`
+    KEY1="double-quoted-value"
+    KEY2='single-quoted-value'
+  `);
+  expect(res.KEY1).toBe("double-quoted-value");
+  expect(res.KEY2).toBe("single-quoted-value");
+});
+
+test("keeps '=' inside values (e.g. base64 keys)", () => {
+  const res = parseEnv("TOKEN=abc==def");
+  expect(res.TOKEN).toBe("abc==def");
+});
diff --git a/src/env.ts b/src/env.ts
new file mode 100644
index 0000000..8182e27
--- /dev/null
+++ b/src/env.ts
@@ -0,0 +1,41 @@
+import { existsSync, readFileSync } from "node:fs";
+
+/**
+ * Parse .env content into key/value pairs. Zero-dependency fallback for the
+ * native `process.loadEnvFile` (Node < 20.12). Supports comments, blank lines,
+ * and single/double-quoted values. Kept intentionally small — not a full
+ * dotenv (no `export` prefix, no inline comments, no variable expansion).
+ */
+export function parseEnv(content: string): Record<string, string> {
+  const env: Record<string, string> = {};
+  for (const line of content.split(/\r?\n/)) {
+    const trimmed = line.trim();
+    if (!trimmed || trimmed.startsWith("#")) continue;
+    const idx = trimmed.indexOf("=");
+    if (idx === -1) continue;
+    const key = trimmed.slice(0, idx).trim();
+    let val = trimmed.slice(idx + 1).trim();
+    if ((val.startsWith('"') && val.endsWith('"')) || (val.startsWith("'") && val.endsWith("'"))) {
+      val = val.slice(1, -1);
+    }
+    env[key] = val;
+  }
+  return env;
+}
+
+/** Load a local .env into process.env if present. Native loader first, parser fallback. */
+export function loadDotEnv(path = ".env"): void {
+  if (!existsSync(path)) return;
+  try {
+    if (typeof process.loadEnvFile === "function") {
+      process.loadEnvFile(path);
+    } else {
+      const parsed = parseEnv(readFileSync(path, "utf8"));
+      for (const [key, val] of Object.entries(parsed)) {
+        process.env[key] = val;
+      }
+    }
+  } catch (err) {
+    console.warn("Warning: Failed to parse .env file:", err);
+  }
+}