diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8998ae4..e6abca2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,18 @@
 
 All notable changes to this project will be documented in this file.
 
+## 1.9.0 - 2026-09-15
+
+Changes since 1.8.0:
+
+### Added
+
+- Added `context.assert(fn, description)` for scenario/snippet script steps: runs the given function, requires it to return `true`, logs the outcome (`log` on success, `error` on failure or exception), and throws to stop the step on failure.
+
+### Changed
+
+- Documented `context.assert` in `docs/scenario.md`.
+
 ## 1.8.0 - 2026-09-15
 
 Changes since 1.7.1:
diff --git a/docs/scenario.md b/docs/scenario.md
index b631d01..fa6edd1 100644
--- a/docs/scenario.md
+++ b/docs/scenario.md
@@ -35,6 +35,7 @@ Available in scope:
 - `context.getStepOutput(order)`: prior step output by absolute order (`1`, `2`, ...) or relative (`-1` = previous step)
 - `context.dumpDom(selector?)`: simplified DOM snapshot
 - `context.log(...args)`, `context.warn(...args)`, `context.error(...args)`: structured step logs
+- `context.assert(() => boolean, description)`: runs the arrow function and requires it to return `true`. Logs `description` (as a `log` entry on success, as an `error` entry on failure or exception), then throws to stop the step if the function returned anything other than `true` or threw
 - `context.runSnippet(name, ...args)`: execute stored snippet code with the same context
 - `context.getScenarioFiles(opts?)`: list files uploaded to the scenario (`limit`, `offset`)
 - `context.downloadFile(url, opts?)`: fetch `url` and save the result as a run artifact (requires a real scenario run — throws when invoked ad hoc, e.g. via the `exec_code` MCP tool). `opts` may include `method`, `headers`, `body`, `filename`. `url` also accepts a `data:` URI (`data:<mediaType>;base64,<data>` or `data:<mediaType>,<percent-encoded data>`) to save content generated in-script (e.g. a credential JWT) directly, without an actual network fetch.
diff --git a/package.json b/package.json
index c6007fe..a0149ba 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "liqa",
-  "version": "1.8.0",
+  "version": "1.9.0",
   "private": true,
   "workspaces": [
     "server",
diff --git a/server/src/code-executor/code-executor.service.ts b/server/src/code-executor/code-executor.service.ts
index 81700e0..05de3b7 100644
--- a/server/src/code-executor/code-executor.service.ts
+++ b/server/src/code-executor/code-executor.service.ts
@@ -42,6 +42,15 @@ export interface ScriptContext {
   log: (...args: unknown[]) => void;
   warn: (...args: unknown[]) => void;
   error: (...args: unknown[]) => void;
+  /**
+   * Runs `fn` and requires it to return `true`. Logs the outcome under
+   * `description`, then throws if `fn` returned anything other than `true`
+   * or threw an exception.
+   */
+  assert: (
+    fn: () => boolean | Promise<boolean>,
+    description: string,
+  ) => Promise<void>;
   /** Runs a named snippet with the same context, plus any extra positional args. */
   runSnippet: (alias: string, ...args: unknown[]) => Promise<unknown>;
   /** Returns metadata + absolute disk path for files attached to the current scenario. */
@@ -141,6 +150,28 @@ export class CodeExecutorService {
         log: (...args: unknown[]) => scriptLog("log", toStr(args)),
         warn: (...args: unknown[]) => scriptLog("warn", toStr(args)),
         error: (...args: unknown[]) => scriptLog("error", toStr(args)),
+        assert: async (
+          fn: () => boolean | Promise<boolean>,
+          description: string,
+        ): Promise<void> => {
+          let passed: boolean;
+          let failureReason: string | undefined;
+          try {
+            passed = (await fn()) === true;
+          } catch (err) {
+            passed = false;
+            failureReason = (err as Error).message;
+          }
+          if (passed) {
+            scriptLog("log", `Assertion passed: ${description}`);
+            return;
+          }
+          const message = failureReason
+            ? `Assertion failed: ${description} (${failureReason})`
+            : `Assertion failed: ${description}`;
+          scriptLog("error", message);
+          throw new Error(message);
+        },
         getStepOutput: getStepOutput ?? (() => Promise.resolve(null)),
         getCredential: (alias: string): unknown => {
           if (!(alias in credMap)) {