diff --git a/README.md b/README.md
index 633e9ef..2786685 100644
--- a/README.md
+++ b/README.md
@@ -21,6 +21,31 @@ pnpm dev
 
 The first account created becomes **admin**. Later accounts are created from Users.
 
+## Script contract
+
+Each script is `async function main(ctx)` and **must** return:
+
+```js
+{ output, context?, skipRemaining? }
+```
+
+| Field | Meaning |
+|---|---|
+| `ctx.data` | This step’s input (trigger payload, previous `output`, or DAG `needs`) |
+| `ctx.context` | Run clipboard (plain object, default `{}`) |
+| `ctx.config` | This step’s YAML config |
+| `output` | Becomes the **next** step’s `data` |
+| `context` | Next snapshot of the bag. Omitted → keep incoming |
+| `skipRemaining` | Stop later steps. Sibling of `output`/`context`, not inside `output` |
+
+Returning the full `ctx` is an error. Mutating `ctx.data` or `ctx.context` does not persist unless returned.
+
+YAML **SET** evaluates JSONata against the full `ctx`; the result is `output` (the next step’s data). `jsonata.js` does the same.
+
+DAG `needs` assemble this step’s `data` from upstream **outputs**. Independent steps in the same wave share a context snapshot; sibling writes to the same context key fail the run.
+
+Optional `script.meta.reads = "ctx"` documents expression hosts. `meta.input` / `meta.output` / `meta.context` describe `data`, the return pipe, and clipboard keys.
+
 ## Scripts
 
 | Command | Description |
diff --git a/packages/server/registry.js b/packages/server/registry.js
index 474da1d..3a00336 100644
--- a/packages/server/registry.js
+++ b/packages/server/registry.js
@@ -15,6 +15,13 @@ import {
   namespacedPath,
   parseScriptStep,
 } from "./workflow-parse.js";
+import {
+  chainCtx,
+  mergeContextWave,
+  normalizeContext,
+  normalizeStepResult,
+  storedEnvelope,
+} from "./step-result.js";
 import * as fsStore from "./fs-store.js";
 import {
   checkHttpAuth,
@@ -327,24 +334,15 @@ export function createRegistry(server) {
     );
   }
 
-  function isSkipRemaining(result) {
-    return (
-      result != null &&
-      typeof result === "object" &&
-      !Array.isArray(result) &&
-      /** @type {{ skipRemaining?: unknown }} */ (result).skipRemaining === true
-    );
-  }
-
   /**
    * @param {import("./workflow-parse.js").CompiledStep} parsed
    * @param {number} index
-   * @param {unknown} ctx
+   * @param {import("./step-result.js").StepResult} last
    * @param {string} runId
    * @param {import("pino").Logger} runLog
    * @param {string} reason
    */
-  async function markStepSkipped(parsed, index, ctx, runId, runLog, reason) {
+  async function markStepSkipped(parsed, index, last, runId, runLog, reason) {
     const script = parsed.kind === "set" ? SET_STEP_SCRIPT : parsed.script;
     const step = await store.startStep({
       runId,
@@ -354,12 +352,12 @@ export function createRegistry(server) {
     });
     const stepLog = runLog.child({ stepId: step.id, script });
     stepLog.debug({ reason }, "step skipped");
-    await store.finishStep(step.id, "skipped", ctx, reason);
+    await store.finishStep(step.id, "skipped", storedEnvelope(last), reason);
   }
 
   /**
    * @param {import("./workflow-parse.js").CompiledScripts} compiled
-   * @param {{ data?: unknown }} ctx
+   * @param {{ data?: unknown, context?: Record<string, unknown> }} ctx
    * @param {string} runId
    * @param {import("pino").Logger} runLog
    * @param {string} key
@@ -367,11 +365,17 @@ export function createRegistry(server) {
    * @param {number} depth
    */
   async function runLinearSteps(compiled, ctx, runId, runLog, key, owner, depth) {
-    let next = ctx;
+    /** @type {import("./step-result.js").StepResult} */
+    let last = {
+      output: ctx.data,
+      context: normalizeContext(ctx.context),
+      skipRemaining: false,
+    };
+    let next = { data: ctx.data, context: last.context };
     for (let i = 0; i < compiled.order.length; i++) {
       const index = compiled.order[i];
       const parsed = compiled.steps[index];
-      next = await runCompiledStep(
+      last = await runCompiledStep(
         parsed,
         next,
         index,
@@ -381,13 +385,14 @@ export function createRegistry(server) {
         owner,
         depth,
       );
-      if (isSkipRemaining(next)) {
+      next = chainCtx(last);
+      if (last.skipRemaining) {
         for (let j = i + 1; j < compiled.order.length; j++) {
           const laterIndex = compiled.order[j];
           await markStepSkipped(
             compiled.steps[laterIndex],
             laterIndex,
-            next,
+            last,
             runId,
             runLog,
             "skipRemaining",
@@ -396,12 +401,12 @@ export function createRegistry(server) {
         break;
       }
     }
-    return next;
+    return last;
   }
 
   /**
    * @param {import("./workflow-parse.js").CompiledScripts} compiled
-   * @param {{ data?: unknown }} ctx
+   * @param {{ data?: unknown, context?: Record<string, unknown> }} ctx
    * @param {string} runId
    * @param {import("pino").Logger} runLog
    * @param {string} key
@@ -412,30 +417,91 @@ export function createRegistry(server) {
     const triggerData = ctx.data;
     /** @type {Map<string, unknown>} */
     const outputsById = new Map();
-    let last = ctx;
+    /** @type {Map<string, number>} */
+    const idToIndex = new Map();
+    for (const step of compiled.steps) {
+      if (step.id) idToIndex.set(step.id, step.index);
+    }
 
-    for (const [orderIndex, stepIndex] of compiled.order.entries()) {
-      const parsed = compiled.steps[stepIndex];
-      const data = mergeStepData(parsed, outputsById, triggerData);
-      last = await runCompiledStep(
-        parsed,
-        { ...ctx, data },
-        orderIndex,
-        runId,
-        runLog,
-        key,
-        owner,
-        depth,
-      );
-      if (parsed.id) {
-        outputsById.set(parsed.id, last);
+    const remaining = new Set(compiled.steps.map((s) => s.index));
+    const completed = new Set();
+    let context = normalizeContext(ctx.context);
+    /** @type {import("./step-result.js").StepResult} */
+    let last = {
+      output: ctx.data,
+      context,
+      skipRemaining: false,
+    };
+    let execIndex = 0;
+
+    /**
+     * @param {import("./workflow-parse.js").CompiledStep} step
+     */
+    function needsMet(step) {
+      if (step.needsKind === "none" || step.needs.length === 0) return true;
+      return step.needs.every((edge) => completed.has(idToIndex.get(edge.from)));
+    }
+
+    while (remaining.size) {
+      const wave = compiled.steps
+        .filter((s) => remaining.has(s.index) && needsMet(s))
+        .sort((a, b) => a.index - b.index);
+      if (wave.length === 0) {
+        throw new Error("Workflow has a cycle");
       }
-      if (isSkipRemaining(last)) {
-        for (let j = orderIndex + 1; j < compiled.order.length; j++) {
-          const laterParsed = compiled.steps[compiled.order[j]];
+
+      const snapshot = { ...context };
+      /** @type {Array<{ id: string, context: unknown }>} */
+      const patches = [];
+      let skipRest = false;
+
+      for (const parsed of wave) {
+        remaining.delete(parsed.index);
+        const index = execIndex;
+        execIndex += 1;
+        if (skipRest) {
           await markStepSkipped(
-            laterParsed,
-            j,
+            parsed,
+            index,
+            last,
+            runId,
+            runLog,
+            "skipRemaining",
+          );
+          continue;
+        }
+        const data = mergeStepData(parsed, outputsById, triggerData);
+        last = await runCompiledStep(
+          parsed,
+          { data, context: { ...snapshot } },
+          index,
+          runId,
+          runLog,
+          key,
+          owner,
+          depth,
+        );
+        if (parsed.id) {
+          outputsById.set(parsed.id, last.output);
+        }
+        patches.push({
+          id: parsed.id ?? String(parsed.index),
+          context: last.context,
+        });
+        if (last.skipRemaining) skipRest = true;
+      }
+
+      context = mergeContextWave(snapshot, patches);
+      last = { ...last, context };
+
+      if (skipRest) {
+        for (const later of compiled.steps.filter((s) => remaining.has(s.index))) {
+          remaining.delete(later.index);
+          const index = execIndex;
+          execIndex += 1;
+          await markStepSkipped(
+            later,
+            index,
             last,
             runId,
             runLog,
@@ -444,7 +510,10 @@ export function createRegistry(server) {
         }
         break;
       }
+
+      for (const parsed of wave) completed.add(parsed.index);
     }
+
     return last;
   }
 
@@ -483,13 +552,14 @@ export function createRegistry(server) {
 
   /**
    * @param {import("./workflow-parse.js").CompiledStep} parsed
-   * @param {{ data?: unknown, config?: unknown }} ctx
+   * @param {{ data?: unknown, context?: unknown, config?: unknown }} ctx
    * @param {number} index
    * @param {string} runId
    * @param {import("pino").Logger} runLog
    * @param {string} key
    * @param {string} owner
    * @param {number} depth
+   * @returns {Promise<import("./step-result.js").StepResult>}
    */
   async function runCompiledStep(
     parsed,
@@ -503,6 +573,12 @@ export function createRegistry(server) {
   ) {
     const script = parsed.kind === "set" ? SET_STEP_SCRIPT : parsed.script;
     const config = parsed.config;
+    const incomingContext = normalizeContext(ctx.context);
+    const stepCtx = {
+      data: ctx.data,
+      context: incomingContext,
+      config,
+    };
     const step = await store.startStep({
       runId,
       index,
@@ -512,29 +588,36 @@ export function createRegistry(server) {
     const stepLog = runLog.child({ stepId: step.id, script });
     try {
       if (parsed.when) {
-        const whenResult = await evaluateJsonata(parsed.when, ctx);
+        const whenResult = await evaluateJsonata(parsed.when, stepCtx);
         if (!isJsonataTruthy(whenResult)) {
           stepLog.debug({ when: parsed.when }, "step skipped");
-          await store.finishStep(step.id, "skipped", ctx, "when condition");
-          return ctx;
+          const skipped = {
+            output: stepCtx.data,
+            context: incomingContext,
+            skipRemaining: false,
+          };
+          await store.finishStep(step.id, "skipped", storedEnvelope(skipped), "when condition");
+          return skipped;
         }
       }
       if (parsed.kind === "set") {
-        if (ctx == null || typeof ctx !== "object" || Array.isArray(ctx)) {
-          throw new Error("set requires an object context");
-        }
-        const value = await evaluateJsonata(parsed.expression, ctx);
-        const result = { ...ctx, [parsed.as]: value };
-        await store.finishStep(step.id, "success", result);
+        const value = await evaluateJsonata(parsed.expression, stepCtx);
+        const result = {
+          output: value,
+          context: incomingContext,
+          skipRemaining: false,
+        };
+        await store.finishStep(step.id, "success", storedEnvelope(result));
         return result;
       }
-      const result = await runScript(script, { ...ctx, config }, {
+      const raw = await runScript(script, stepCtx, {
         log: stepLog,
         workflowName: key,
         owner,
         $workflows: createWorkflowsApi(owner, key, runId, depth),
       });
-      await store.finishStep(step.id, "success", result);
+      const result = normalizeStepResult(raw, incomingContext, script);
+      await store.finishStep(step.id, "success", storedEnvelope(result));
       return result;
     } catch (err) {
       await store.finishStep(step.id, "failed", null, err);
@@ -544,7 +627,7 @@ export function createRegistry(server) {
 
   /**
    * @param {string} key
-   * @param {{ data?: unknown }} context
+   * @param {{ data?: unknown, context?: unknown }} context
    * @param {{ type: string, detail?: string | null }} trigger
    * @param {{
    *   parentRunId?: string | null,
@@ -580,8 +663,8 @@ export function createRegistry(server) {
     runLog.debug(detach ? "running workflow (detached)" : "running workflow");
 
     const initialCtx = {
-      ...context,
       data: context.data ?? workflow.data ?? null,
+      context: normalizeContext(context.context),
     };
 
     const execute = async () => {
@@ -609,8 +692,8 @@ export function createRegistry(server) {
             depth,
           );
         }
-        await store.finishRun(run.id, "success", ctx);
-        return { runId: run.id, status: "success", result: ctx };
+        await store.finishRun(run.id, "success", storedEnvelope(ctx));
+        return { runId: run.id, status: "success", result: storedEnvelope(ctx) };
       } catch (err) {
         runLog.error({ err }, "workflow failed");
         await store.finishRun(run.id, "failed", null, err);
diff --git a/packages/server/scripts/fetch-binary.js b/packages/server/scripts/fetch-binary.js
index 8712dda..abeb8a8 100644
--- a/packages/server/scripts/fetch-binary.js
+++ b/packages/server/scripts/fetch-binary.js
@@ -1,7 +1,15 @@
-function ensureDataObject(ctx) {
-  if (ctx.data == null || typeof ctx.data !== "object" || Array.isArray(ctx.data)) {
-    ctx.data = {};
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
   }
+  return {};
+}
+
+function mergeData(data) {
+  if (data != null && typeof data === "object" && !Array.isArray(data)) {
+    return { ...data };
+  }
+  return {};
 }
 
 function filenameFromUrl(url) {
@@ -38,8 +46,6 @@ function resolveUrl(ctx) {
 }
 
 async function fetchBinary(ctx) {
-  ensureDataObject(ctx);
-
   const url = resolveUrl(ctx);
   if (!url) {
     throw new Error(
@@ -55,27 +61,32 @@ async function fetchBinary(ctx) {
   const response = await $axios.get(url, { responseType: "arraybuffer" });
   const file = Buffer.from(response.data ?? []);
   const contentType = String(response.headers?.["content-type"] ?? "application/octet-stream");
-  const filename = ctx.config?.filename || ctx.data.filename || filenameFromUrl(url);
+  const filename = ctx.config?.filename || ctx.data?.filename || filenameFromUrl(url);
 
-  ctx.data[outputVar] = file;
-  ctx.data.filename = filename;
-  ctx.data.contentType = contentType;
+  const extra = {
+    [outputVar]: file,
+    filename,
+    contentType,
+  };
 
   log.info(
     { outputVar, filename, contentType, length: file.length },
     "fetch-binary: saved",
   );
 
-  return ctx;
+  return {
+    output: { ...mergeData(ctx.data), ...extra },
+    context: { ...passContext(ctx), ...extra },
+  };
 }
 
 fetchBinary.meta = {
-  description: "Download a binary URL into ctx.data as a Buffer",
+  description: "Download a binary URL and add the Buffer to output (keeps previous data fields)",
   previewConfigKey: "url",
   config: {
     url: { type: "string", required: false, description: "Direct download URL" },
     urlVar: { type: "string", required: false, description: "Key in ctx.data that holds the URL" },
-    outputVar: { type: "string", default: "file", description: "ctx.data key for the Buffer" },
+    outputVar: { type: "string", default: "file", description: "output key for the Buffer" },
     filename: { type: "string", required: false, description: "Override saved filename" },
   },
   input: {
@@ -88,6 +99,11 @@ fetchBinary.meta = {
     filename: { type: "string" },
     contentType: { type: "string" },
   },
+  context: {
+    file: { type: "buffer", description: "Downloaded bytes (or ctx.config.outputVar)" },
+    filename: { type: "string" },
+    contentType: { type: "string" },
+  },
   example: {
     data: { attach: "https://example.com/image.png" },
     config: { outputVar: "file" },
diff --git a/packages/server/scripts/fetch-html.js b/packages/server/scripts/fetch-html.js
index 3b7be2e..93ac59e 100644
--- a/packages/server/scripts/fetch-html.js
+++ b/packages/server/scripts/fetch-html.js
@@ -1,10 +1,11 @@
 import { parse } from "node-html-parser";
 import jsonata from "jsonata";
 
-function ensureDataObject(ctx) {
-  if (ctx.data == null || typeof ctx.data !== "object" || Array.isArray(ctx.data)) {
-    ctx.data = {};
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
   }
+  return {};
 }
 
 function serializeElement(el) {
@@ -43,8 +44,6 @@ async function fetchHtml(ctx) {
     throw new Error("fetch-html: ctx.config.outputVar is required when selector or jsonata is set");
   }
 
-  ensureDataObject(ctx);
-
   log.info({ url }, "fetch-html: fetching page");
   const response = await $axios.get(url);
   log.info(
@@ -52,19 +51,20 @@ async function fetchHtml(ctx) {
     "fetch-html: fetch complete",
   );
 
-  ctx.data.httpResponse = String(response.data ?? "");
+  /** @type {Record<string, unknown>} */
+  const output = { httpResponse: String(response.data ?? "") };
   log.info(
-    { length: ctx.data.httpResponse.length },
+    { length: String(output.httpResponse).length },
     "fetch-html: saved httpResponse",
   );
 
   if (selector) {
     log.info({ selector, outputVar }, "fetch-html: selecting elements");
-    const root = parse(ctx.data.httpResponse);
+    const root = parse(String(output.httpResponse));
     const elements = root.querySelectorAll(selector);
-    ctx.data[outputVar] = elements.map(serializeElement);
+    output[outputVar] = elements.map(serializeElement);
     log.info(
-      { outputVar, count: ctx.data[outputVar].length },
+      { outputVar, count: output[outputVar].length },
       "fetch-html: saved selector matches",
     );
   }
@@ -72,16 +72,15 @@ async function fetchHtml(ctx) {
   if (jsonataExpr) {
     log.info({ outputVar, jsonata: jsonataExpr }, "fetch-html: evaluating jsonata");
     const expression = jsonata(jsonataExpr);
-    const input = ctx.data[outputVar];
-    const result = await expression.evaluate(input);
-    ctx.data[outputVar] = result;
+    const result = await expression.evaluate(output[outputVar]);
+    output[outputVar] = result;
     log.info(
       { outputVar, result: previewValue(result) },
       "fetch-html: saved jsonata result",
     );
   }
 
-  return ctx;
+  return { output, context: { ...passContext(ctx), ...output } };
 }
 
 fetchHtml.meta = {
@@ -100,7 +99,10 @@ fetchHtml.meta = {
   },
   input: {},
   output: {
-    httpResponse: { type: "string", description: "Raw HTML" },
+    httpResponse: { type: "string", description: "Raw HTML (overwritten when outputVar is httpResponse)" },
+  },
+  context: {
+    httpResponse: { type: "any", description: "Same keys as output" },
   },
   example: {
     data: {},
diff --git a/packages/server/scripts/fetch-http.js b/packages/server/scripts/fetch-http.js
index 1246036..e276dd3 100644
--- a/packages/server/scripts/fetch-http.js
+++ b/packages/server/scripts/fetch-http.js
@@ -1,9 +1,10 @@
 const HTTP_METHODS = ["GET", "HEAD", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"];
 
-function ensureDataObject(ctx) {
-  if (ctx.data == null || typeof ctx.data !== "object" || Array.isArray(ctx.data)) {
-    ctx.data = {};
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
   }
+  return {};
 }
 
 function isPlainObject(value) {
@@ -40,7 +41,6 @@ function normalizeHeaders(value, label) {
       headers[key] = String(val);
       continue;
     }
-    // Secret wrappers are unwrapped by $axios; do not String() them.
     if (typeof val === "object") {
       headers[key] = val;
       continue;
@@ -88,8 +88,6 @@ async function fetchHttp(ctx) {
   const headers = resolveHeaders(ctx);
   const body = resolveBody(ctx);
 
-  ensureDataObject(ctx);
-
   /** @type {Record<string, unknown>} */
   const request = { url, method, headers };
   if (body.present && method !== "HEAD") {
@@ -103,14 +101,16 @@ async function fetchHttp(ctx) {
     "fetch-http: fetch complete",
   );
 
-  ctx.data.httpResponse = response.data;
-  ctx.data.httpStatus = response.status;
+  const output = {
+    httpResponse: response.data,
+    httpStatus: response.status,
+  };
   log.info(
-    { status: ctx.data.httpStatus, length: responseSize(ctx.data.httpResponse) },
+    { status: output.httpStatus, length: responseSize(output.httpResponse) },
     "fetch-http: saved httpResponse",
   );
 
-  return ctx;
+  return { output, context: { ...passContext(ctx), ...output } };
 }
 
 fetchHttp.meta = {
@@ -154,6 +154,10 @@ fetchHttp.meta = {
     httpResponse: { type: "any", description: "Response body as returned by the server" },
     httpStatus: { type: "number", description: "HTTP status code" },
   },
+  context: {
+    httpResponse: { type: "any", description: "Same as output.httpResponse" },
+    httpStatus: { type: "number", description: "Same as output.httpStatus" },
+  },
   example: {
     data: {},
     config: {
diff --git a/packages/server/scripts/fetch-rss-feed.js b/packages/server/scripts/fetch-rss-feed.js
index afcb6a5..7e8c170 100644
--- a/packages/server/scripts/fetch-rss-feed.js
+++ b/packages/server/scripts/fetch-rss-feed.js
@@ -1,10 +1,11 @@
 import rssParser from "rss-parser";
 import jsonata from "jsonata";
 
-function ensureDataObject(ctx) {
-  if (ctx.data == null || typeof ctx.data !== "object" || Array.isArray(ctx.data)) {
-    ctx.data = {};
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
   }
+  return {};
 }
 
 function previewValue(value) {
@@ -28,8 +29,6 @@ async function fetchRssFeed(ctx) {
     throw new Error("fetch-rss-feed: ctx.config.outputVar is required when jsonata is set");
   }
 
-  ensureDataObject(ctx);
-
   log.info({ url }, "fetch-rss-feed: fetching feed");
   const parser = new rssParser({
     customFields: {
@@ -46,7 +45,8 @@ async function fetchRssFeed(ctx) {
     "fetch-rss-feed: fetch complete",
   );
 
-  ctx.data.rssFeed = feed;
+  /** @type {Record<string, unknown>} */
+  const output = { rssFeed: feed };
   log.info(
     { title: feed.title, itemCount },
     "fetch-rss-feed: saved rssFeed",
@@ -56,14 +56,14 @@ async function fetchRssFeed(ctx) {
     log.info({ outputVar, jsonata: jsonataExpr }, "fetch-rss-feed: evaluating jsonata");
     const expression = jsonata(jsonataExpr);
     const result = await expression.evaluate(feed);
-    ctx.data[outputVar] = result;
+    output[outputVar] = result;
     log.info(
       { outputVar, result: previewValue(result) },
       "fetch-rss-feed: saved jsonata result",
     );
   }
 
-  return ctx;
+  return { output, context: { ...passContext(ctx), ...output } };
 }
 
 fetchRssFeed.meta = {
@@ -75,7 +75,7 @@ fetchRssFeed.meta = {
     outputVar: {
       type: "string",
       required: false,
-      description: "Required when jsonata is set; destination on ctx.data",
+      description: "Required when jsonata is set; key on output and context",
     },
     jsonata: {
       type: "string",
@@ -89,6 +89,9 @@ fetchRssFeed.meta = {
   output: {
     rssFeed: { type: "object", description: "Parsed RSS/Atom feed from rss-parser" },
   },
+  context: {
+    rssFeed: { type: "object", description: "Same as output.rssFeed (plus outputVar when set)" },
+  },
   example: {
     data: {},
     config: {
diff --git a/packages/server/scripts/fingerprint.js b/packages/server/scripts/fingerprint.js
index 1baf860..522ed16 100644
--- a/packages/server/scripts/fingerprint.js
+++ b/packages/server/scripts/fingerprint.js
@@ -1,9 +1,17 @@
 import jsonata from "jsonata";
 
-function ensureDataObject(ctx) {
-  if (ctx.data == null || typeof ctx.data !== "object" || Array.isArray(ctx.data)) {
-    ctx.data = {};
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
   }
+  return {};
+}
+
+function mergeData(data) {
+  if (data != null && typeof data === "object" && !Array.isArray(data)) {
+    return { ...data };
+  }
+  return {};
 }
 
 async function fingerprint(ctx) {
@@ -28,13 +36,14 @@ async function fingerprint(ctx) {
     maxAge: ctx.config?.maxAge,
   });
 
-  ensureDataObject(ctx);
-  ctx.data.fingerprint = result.hash;
-  ctx.data.fingerprintChanged = result.changed;
-  ctx.data.fingerprintPrevious = result.previous;
-  ctx.data.fingerprintAt = result.changed ? result.at : result.previousAt;
-  ctx.data.fingerprintAge = result.ageMs;
-  ctx.data.fingerprintExpired = result.expired;
+  const extra = {
+    fingerprint: result.hash,
+    fingerprintChanged: result.changed,
+    fingerprintPrevious: result.previous,
+    fingerprintAt: result.changed ? result.at : result.previousAt,
+    fingerprintAge: result.ageMs,
+    fingerprintExpired: result.expired,
+  };
 
   log.info(
     {
@@ -46,17 +55,22 @@ async function fingerprint(ctx) {
     "fingerprint: result",
   );
 
+  /** @type {{ output: Record<string, unknown>, context: Record<string, unknown>, skipRemaining?: true }} */
+  const envelope = {
+    output: { ...mergeData(ctx.data), ...extra },
+    context: { ...passContext(ctx), ...extra },
+  };
   if (!result.changed && skipRemaining) {
-    ctx.skipRemaining = true;
+    envelope.skipRemaining = true;
   }
-
-  return ctx;
+  return envelope;
 }
 
 fingerprint.meta = {
   description:
     "Hash a value, compare it to the last stored fingerprint, and skip remaining steps when unchanged",
   previewConfigKey: "key",
+  reads: "ctx",
   config: {
     key: {
       type: "string",
@@ -88,6 +102,14 @@ fingerprint.meta = {
     fingerprintAge: { type: "number", required: false, description: "Age in milliseconds" },
     fingerprintExpired: { type: "boolean" },
   },
+  context: {
+    fingerprint: { type: "string" },
+    fingerprintChanged: { type: "boolean" },
+    fingerprintPrevious: { type: "string", required: false },
+    fingerprintAt: { type: "string", required: false },
+    fingerprintAge: { type: "number", required: false },
+    fingerprintExpired: { type: "boolean" },
+  },
   example: {
     data: { item: { guid: "https://example.com/post-1" } },
     config: {
diff --git a/packages/server/scripts/get-current-time.js b/packages/server/scripts/get-current-time.js
index ab3231c..ad34931 100644
--- a/packages/server/scripts/get-current-time.js
+++ b/packages/server/scripts/get-current-time.js
@@ -1,22 +1,30 @@
-// this script will get current time
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
+  }
+  return {};
+}
 
-function getCurrentTime() {
-    return {
-        data: {
-            datetime: new Date().toISOString(),
-            processId: "1234"
-        }
-    }
+function getCurrentTime(ctx) {
+  const output = {
+    datetime: new Date().toISOString(),
+    processId: "1234",
+  };
+  return { output, context: { ...passContext(ctx), ...output } };
 }
 
 getCurrentTime.meta = {
-  description: "Return the current time as ctx.data.datetime",
+  description: "Return the current time as output.datetime",
   config: {},
   input: {},
   output: {
     datetime: { type: "string", description: "ISO timestamp" },
     processId: { type: "string" },
   },
+  context: {
+    datetime: { type: "string", description: "ISO timestamp" },
+    processId: { type: "string" },
+  },
   example: {
     data: {},
     config: {},
diff --git a/packages/server/scripts/get-secret.js b/packages/server/scripts/get-secret.js
index 2212955..123a660 100644
--- a/packages/server/scripts/get-secret.js
+++ b/packages/server/scripts/get-secret.js
@@ -1,3 +1,17 @@
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
+  }
+  return {};
+}
+
+function mergeData(data) {
+  if (data != null && typeof data === "object" && !Array.isArray(data)) {
+    return { ...data };
+  }
+  return {};
+}
+
 async function getSecret(ctx) {
   const name = ctx.config?.name;
   if (typeof name !== "string" || name.length === 0) {
@@ -9,19 +23,16 @@ async function getSecret(ctx) {
       : name;
 
   const value = await $secrets.get(name);
-  const base =
-    ctx != null && typeof ctx === "object" && !Array.isArray(ctx) ? { ...ctx } : {};
-  const data =
-    base.data != null && typeof base.data === "object" && !Array.isArray(base.data)
-      ? { ...base.data }
-      : {};
-  data[as] = value;
-  return { ...base, data };
+  const extra = { [as]: value };
+  return {
+    output: { ...mergeData(ctx.data), ...extra },
+    context: { ...passContext(ctx), ...extra },
+  };
 }
 
 getSecret.meta = {
   description:
-    "Load a named secret for this workflow owner into ctx.data. The value is wrapped and redacted in logs.",
+    "Load a named secret for this workflow owner onto output and context. The value is wrapped and redacted in logs.",
   previewConfigKey: "name",
   config: {
     name: {
@@ -32,16 +43,12 @@ getSecret.meta = {
     as: {
       type: "string",
       required: false,
-      description: "ctx.data field to write (defaults to name)",
+      description: "Field name on output and context (defaults to name)",
     },
   },
   input: {},
-  output: {
-    data: {
-      type: "object",
-      description: "Previous ctx.data plus the retrieved Secret at [as]",
-    },
-  },
+  output: {},
+  context: {},
   example: {
     data: {},
     config: { name: "ntfy_token", as: "ntfyToken" },
diff --git a/packages/server/scripts/jsonata.js b/packages/server/scripts/jsonata.js
index 5948104..b05cf24 100644
--- a/packages/server/scripts/jsonata.js
+++ b/packages/server/scripts/jsonata.js
@@ -1,26 +1,34 @@
 import jsonata from "jsonata";
 
 async function jsonataFn(ctx) {
-    log.info({ctx}, "jsonata: context")
-    log.info("jsonata: evaluating expression %s", ctx.config.expression);
-    const expression = jsonata(ctx.config.expression);
-    const result = await expression.evaluate(ctx.data);
-    log.info({result}, "jsonata: expression result");
-    return result;
+  log.info({ ctx }, "jsonata: context");
+  log.info("jsonata: evaluating expression %s", ctx.config.expression);
+  const expression = jsonata(ctx.config.expression);
+  const result = await expression.evaluate(ctx);
+  log.info({ result }, "jsonata: expression result");
+  return {
+    output: result,
+    context:
+      ctx.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)
+        ? ctx.context
+        : {},
+  };
 }
 
 jsonataFn.meta = {
-  description: "Evaluate a JSONata expression against ctx.data and return the result as the next context",
+  description:
+    "Evaluate a JSONata expression against the full ctx (data, context, config); the result is the next data",
   previewConfigKey: "expression",
+  reads: "ctx",
   config: {
-    expression: { type: "string", required: true, description: "JSONata expression" },
+    expression: { type: "string", required: true, description: "JSONata expression against ctx" },
   },
   input: {},
   output: {},
   example: {
     data: { title: "Hello", url: "https://example.com" },
     config: {
-      expression: '{"data": {"title": title, "message": title, "attach": url}}',
+      expression: '{"title": data.title, "message": data.title, "attach": data.url}',
     },
   },
 };
diff --git a/packages/server/scripts/ntfy.js b/packages/server/scripts/ntfy.js
index 408c600..3c589f5 100644
--- a/packages/server/scripts/ntfy.js
+++ b/packages/server/scripts/ntfy.js
@@ -1,5 +1,12 @@
 import jsonata from "jsonata";
 
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
+  }
+  return {};
+}
+
 function ntfyHeaders(ctx) {
   const headers = {};
 
@@ -72,11 +79,14 @@ async function ntfy(ctx) {
         "ntfy: skipped, fingerprint unchanged",
       );
       return {
-        sent: "false",
-        skipped: true,
-        fingerprint: checked.hash,
-        fingerprintAt: checked.previousAt,
-        fingerprintAge: checked.ageMs,
+        output: {
+          sent: "false",
+          skipped: true,
+          fingerprint: checked.hash,
+          fingerprintAt: checked.previousAt,
+          fingerprintAge: checked.ageMs,
+        },
+        context: passContext(ctx),
       };
     }
     fp = checked;
@@ -126,7 +136,7 @@ async function ntfy(ctx) {
     sent.fingerprint = stored.hash;
     sent.fingerprintAt = stored.at;
   }
-  return sent;
+  return { output: sent, context: passContext(ctx) };
 }
 
 ntfy.meta = {
@@ -147,7 +157,7 @@ ntfy.meta = {
     fingerprintJsonata: {
       type: "string",
       required: false,
-      description: "JSONata against ctx; default hashes title, message, attach, filename, contentType",
+      description: "JSONata against full ctx; default hashes data title, message, attach, filename, contentType",
     },
     fingerprintMaxAge: {
       type: "string",
@@ -163,8 +173,9 @@ ntfy.meta = {
     filename: { type: "string", required: false },
     contentType: { type: "string", required: false },
   },
+  reads: "ctx",
   output: {
-    sent: { type: "string", description: "Replaces the workflow context with { sent: \"true\" }" },
+    sent: { type: "string", description: '"true" when sent, "false" when fingerprint skipped' },
   },
   example: {
     data: { title: "Hello", message: "Hello from jerapah-flow" },
diff --git a/packages/server/scripts/render-template.js b/packages/server/scripts/render-template.js
index 2c066a5..23b2e2d 100644
--- a/packages/server/scripts/render-template.js
+++ b/packages/server/scripts/render-template.js
@@ -70,9 +70,15 @@ async function renderTemplate(ctx) {
   const text = htmlToText(html);
 
   return {
-    html,
-    text,
-    template: templateName,
+    output: {
+      html,
+      text,
+      template: templateName,
+    },
+    context:
+      ctx.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)
+        ? ctx.context
+        : {},
   };
 }
 
diff --git a/packages/server/scripts/send-email.js b/packages/server/scripts/send-email.js
index 9d090e5..8a9c612 100644
--- a/packages/server/scripts/send-email.js
+++ b/packages/server/scripts/send-email.js
@@ -218,13 +218,19 @@ async function sendEmail(ctx) {
   log.info({ messageId: info.messageId }, "send-email: message sent");
 
   return {
-    sent: true,
-    messageId: info.messageId ?? null,
-    from,
-    to,
-    cc: cc ?? null,
-    bcc: bcc ?? null,
-    subject,
+    output: {
+      sent: true,
+      messageId: info.messageId ?? null,
+      from,
+      to,
+      cc: cc ?? null,
+      bcc: bcc ?? null,
+      subject,
+    },
+    context:
+      ctx.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)
+        ? ctx.context
+        : {},
   };
 }
 
diff --git a/packages/server/scripts/trigger-workflow.js b/packages/server/scripts/trigger-workflow.js
index 2f478e2..0639472 100644
--- a/packages/server/scripts/trigger-workflow.js
+++ b/packages/server/scripts/trigger-workflow.js
@@ -1,5 +1,12 @@
 import jsonata from "jsonata";
 
+function passContext(ctx) {
+  if (ctx?.context != null && typeof ctx.context === "object" && !Array.isArray(ctx.context)) {
+    return { ...ctx.context };
+  }
+  return {};
+}
+
 async function triggerWorkflow(ctx) {
   const name = ctx.config?.name;
   if (typeof name !== "string" || name.length === 0) {
@@ -9,27 +16,23 @@ async function triggerWorkflow(ctx) {
   let data = ctx.data;
   const expression = ctx.config?.expression;
   if (typeof expression === "string" && expression.length > 0) {
-    const result = jsonata(expression).evaluate(ctx.data);
+    const result = jsonata(expression).evaluate(ctx);
     data = await result;
   }
 
   const started = await $workflows.trigger(name, data);
-  const triggered = { name, runId: started?.runId ?? null };
-
-  const base =
-    ctx != null && typeof ctx === "object" && !Array.isArray(ctx) ? { ...ctx } : {};
-
-  if (base.data != null && typeof base.data === "object" && !Array.isArray(base.data)) {
-    return { ...base, data: { ...base.data, triggered } };
-  }
-  return { ...base, triggered };
+  return {
+    output: { name, runId: started?.runId ?? null },
+    context: passContext(ctx),
+  };
 }
 
 triggerWorkflow.meta = {
   description:
-    "Fire-and-forget another workflow by YAML name (same owner). Destination must declare triggers: [{ type: workflow }]. Optionally reshape ctx.data with JSONata before sending.",
+    "Fire-and-forget another workflow by YAML name (same owner). Destination must declare triggers: [{ type: workflow }]. Optionally reshape the destination input with JSONata against full ctx.",
   previewConfigKey: "name",
   tags: ["trigger"],
+  reads: "ctx",
   config: {
     name: {
       type: "string",
@@ -40,15 +43,13 @@ triggerWorkflow.meta = {
       type: "string",
       required: false,
       description:
-        "Optional JSONata expression evaluated against ctx.data; result becomes the destination run input",
+        "Optional JSONata expression evaluated against ctx; result becomes the destination run input",
     },
   },
   input: {},
   output: {
-    triggered: {
-      type: "object",
-      description: "Record of the kicked-off run ({ name, runId }); under data when data is an object",
-    },
+    name: { type: "string", description: "Destination workflow name" },
+    runId: { type: "string", description: "Started run id (null if the destination failed to start)" },
   },
   example: {
     data: {
@@ -58,7 +59,7 @@ triggerWorkflow.meta = {
     config: {
       name: "notify-comic",
       expression:
-        '{ "title": title, "message": title, "attach": url }',
+        '{ "title": data.title, "message": data.title, "attach": data.url }',
     },
   },
 };
diff --git a/packages/server/src/api/scripts.js b/packages/server/src/api/scripts.js
index 43772b4..af9c5ef 100644
--- a/packages/server/src/api/scripts.js
+++ b/packages/server/src/api/scripts.js
@@ -6,6 +6,7 @@ import {
 } from "../../script-sandbox.js";
 import * as fsStore from "../../fs-store.js";
 import { createDryRunLogger, safeSerialize } from "./dry-run-logger.js";
+import { normalizeStepResult } from "../../step-result.js";
 
 /**
  * @param {{ referencedScripts: () => Set<string> }} registry
@@ -102,7 +103,7 @@ export default function scriptsPluginFactory(registry) {
         return reply.code(err.statusCode ?? 400).send({ error: err.message });
       }
 
-      const body = /** @type {{ content?: string, data?: unknown, config?: unknown, owner?: string }} */ (
+      const body = /** @type {{ content?: string, data?: unknown, context?: unknown, config?: unknown, owner?: string }} */ (
         req.body ?? {}
       );
       if (typeof body.content !== "string") {
@@ -118,8 +119,13 @@ export default function scriptsPluginFactory(registry) {
         }
       }
 
+      const incomingContext =
+        body.context != null && typeof body.context === "object" && !Array.isArray(body.context)
+          ? body.context
+          : {};
       const ctx = {
         data: body.data ?? null,
+        context: incomingContext,
         config: body.config ?? null,
       };
 
@@ -132,10 +138,13 @@ export default function scriptsPluginFactory(registry) {
           workflowName: "dry-run",
           owner,
         });
-        const output = await fn(ctx);
+        const raw = await fn(ctx);
+        const result = normalizeStepResult(raw, incomingContext, name);
         return {
           status: "success",
-          output: safeSerialize(output),
+          output: safeSerialize(result.output),
+          context: safeSerialize(result.context),
+          skipRemaining: result.skipRemaining,
           error: null,
           logs,
           durationMs: Date.now() - started,
@@ -147,6 +156,8 @@ export default function scriptsPluginFactory(registry) {
         return {
           status: "failed",
           output: null,
+          context: null,
+          skipRemaining: false,
           error: err instanceof Error ? err.message : String(err),
           logs,
           durationMs: Date.now() - started,
diff --git a/packages/server/src/api/workflows.js b/packages/server/src/api/workflows.js
index b4b8da4..1be33bf 100644
--- a/packages/server/src/api/workflows.js
+++ b/packages/server/src/api/workflows.js
@@ -32,7 +32,7 @@ function scriptNames(workflow) {
   for (const raw of workflow.scripts ?? []) {
     try {
       const parsed = parseScriptStep(raw);
-      names.push(parsed.kind === "set" ? `set:${parsed.as}` : parsed.script);
+      names.push(parsed.kind === "set" ? "set" : parsed.script);
     } catch {
       names.push(null);
     }
diff --git a/packages/server/step-result.js b/packages/server/step-result.js
new file mode 100644
index 0000000..af7084f
--- /dev/null
+++ b/packages/server/step-result.js
@@ -0,0 +1,141 @@
+/**
+ * Step return contract: `{ output, context?, skipRemaining? }`.
+ */
+
+/**
+ * @param {unknown} value
+ */
+export function isPlainObject(value) {
+  return value != null && typeof value === "object" && !Array.isArray(value);
+}
+
+/**
+ * @param {unknown} value
+ * @returns {Record<string, unknown>}
+ */
+export function normalizeContext(value) {
+  return isPlainObject(value) ? /** @type {Record<string, unknown>} */ (value) : {};
+}
+
+/**
+ * @typedef {{
+ *   output: unknown,
+ *   context: Record<string, unknown>,
+ *   skipRemaining: boolean,
+ * }} StepResult
+ */
+
+/**
+ * @param {unknown} raw
+ * @param {unknown} incomingContext
+ * @param {string} [label]
+ * @returns {StepResult}
+ */
+export function normalizeStepResult(raw, incomingContext, label = "script") {
+  const incoming = normalizeContext(incomingContext);
+  if (!isPlainObject(raw)) {
+    const got = raw == null ? String(raw) : typeof raw;
+    throw new Error(`${label} must return { output, context }. Got ${got}`);
+  }
+  if (!("output" in raw) && ("data" in raw || "config" in raw)) {
+    throw new Error(
+      `${label} must return { output, context }. Returning the full ctx is no longer valid.`,
+    );
+  }
+
+  let context = incoming;
+  if ("context" in raw) {
+    if (raw.context == null) {
+      context = incoming;
+    } else if (!isPlainObject(raw.context)) {
+      throw new Error(`${label} returned a non-object context`);
+    } else {
+      context = /** @type {Record<string, unknown>} */ (raw.context);
+    }
+  }
+
+  return {
+    output: "output" in raw ? raw.output : null,
+    context,
+    skipRemaining: raw.skipRemaining === true,
+  };
+}
+
+/**
+ * Persistable envelope (omit skipRemaining unless set).
+ * @param {StepResult} result
+ */
+export function storedEnvelope(result) {
+  /** @type {{ output: unknown, context: Record<string, unknown>, skipRemaining?: true }} */
+  const out = { output: result.output, context: result.context };
+  if (result.skipRemaining) out.skipRemaining = true;
+  return out;
+}
+
+/**
+ * Next step ctx (without config).
+ * @param {StepResult} result
+ */
+export function chainCtx(result) {
+  return { data: result.output, context: result.context };
+}
+
+/**
+ * Shallow-merge sibling context diffs vs a shared snapshot.
+ * Fails if two siblings change the same key.
+ *
+ * @param {unknown} snapshot
+ * @param {Array<{ id: string, context: unknown }>} patches
+ * @returns {Record<string, unknown>}
+ */
+export function mergeContextWave(snapshot, patches) {
+  const base = normalizeContext(snapshot);
+  /** @type {Map<string, string>} */
+  const writers = new Map();
+  /** @type {Map<string, { deleted: true } | { value: unknown }>} */
+  const changes = new Map();
+
+  for (const patch of patches) {
+    const who = patch.id;
+    const next = normalizeContext(patch.context);
+    const keys = new Set([...Object.keys(base), ...Object.keys(next)]);
+    for (const key of keys) {
+      const inBase = Object.prototype.hasOwnProperty.call(base, key);
+      const inNext = Object.prototype.hasOwnProperty.call(next, key);
+      if (inBase && inNext && Object.is(base[key], next[key])) continue;
+      if (!inBase && !inNext) continue;
+      if (inBase && !inNext) {
+        rememberChange(writers, changes, key, who, { deleted: true });
+        continue;
+      }
+      if (!inBase || !Object.is(base[key], next[key])) {
+        rememberChange(writers, changes, key, who, { value: next[key] });
+      }
+    }
+  }
+
+  const merged = { ...base };
+  for (const [key, spec] of changes) {
+    if ("deleted" in spec) delete merged[key];
+    else merged[key] = spec.value;
+  }
+  return merged;
+}
+
+/**
+ * @param {Map<string, string>} writers
+ * @param {Map<string, { deleted: true } | { value: unknown }>} changes
+ * @param {string} key
+ * @param {string} who
+ * @param {{ deleted: true } | { value: unknown }} spec
+ */
+function rememberChange(writers, changes, key, who, spec) {
+  const previous = writers.get(key);
+  if (previous != null && previous !== who) {
+    throw new Error(
+      `DAG context key conflict: "${key}" written by "${previous}" and "${who}"`,
+    );
+  }
+  writers.set(key, who);
+  changes.set(key, spec);
+}
diff --git a/packages/server/test/fingerprint-smoke.js b/packages/server/test/fingerprint-smoke.js
index 3331cd3..47e5b60 100644
--- a/packages/server/test/fingerprint-smoke.js
+++ b/packages/server/test/fingerprint-smoke.js
@@ -92,7 +92,7 @@ export default async function (ctx) {
 const scriptOut = await runScriptSource(
   "fingerprint-smoke.js",
   script,
-  { data: { n: 1 } },
+  { data: { n: 1 }, context: {} },
   { log, workflowName: ns },
 );
 if (!scriptOut.changed) throw new Error("sandbox $fingerprint.claim should be new");
diff --git a/packages/server/workflow-parse.js b/packages/server/workflow-parse.js
index 0aa9d5b..059b707 100644
--- a/packages/server/workflow-parse.js
+++ b/packages/server/workflow-parse.js
@@ -1,8 +1,5 @@
 import jsonata from "jsonata";
 
-const AS_IDENT = /^[A-Za-z_][A-Za-z0-9_]*$/;
-const RESERVED_AS = new Set(["data", "config"]);
-
 export const SET_STEP_SCRIPT = "set";
 
 /**
@@ -12,7 +9,6 @@ export const SET_STEP_SCRIPT = "set";
  *   script: string,
  *   config: unknown | null,
  *   expression?: undefined,
- *   as?: undefined,
  *   id: string | null,
  *   needsKind: "none" | "list" | "map",
  *   needs: NeedEdge[],
@@ -21,11 +17,10 @@ export const SET_STEP_SCRIPT = "set";
  * @typedef {{
  *   kind: "set",
  *   script: typeof SET_STEP_SCRIPT,
- *   config: { expression: string, as: string },
+ *   config: { expression: string },
  *   expression: string,
- *   as: string,
  *   id: string | null,
- *   needsKind: "none",
+ *   needsKind: "none" | "list" | "map",
  *   needs: NeedEdge[],
  *   when: string | null,
  * }} ParsedSetStep
@@ -163,9 +158,6 @@ export function compileWorkflowScripts(scripts) {
   if (dagMode) {
     for (const step of steps) {
       const who = step.id ?? String(step.index);
-      if (step.kind === "set") {
-        throw new Error(`set steps are not allowed in DAG workflows (step ${who})`);
-      }
       if (step.when) {
         throw new Error(`when is not allowed in DAG workflows (step ${who})`);
       }
@@ -227,13 +219,10 @@ export function compileWorkflowScripts(scripts) {
 }
 
 /**
- * Prefer a script return's `.data`; otherwise treat the whole return as data.
+ * Upstream DAG output stored in outputsById (already the pipe value).
  * @param {unknown} result
  */
-export function extractStepData(result) {
-  if (result && typeof result === "object" && !Array.isArray(result) && "data" in result) {
-    return result.data;
-  }
+export function extractStepOutput(result) {
   return result ?? null;
 }
 
@@ -248,12 +237,12 @@ export function mergeStepData(step, outputsById, triggerData) {
     return triggerData;
   }
   if (step.needsKind === "list" && step.needs.length === 1) {
-    return extractStepData(outputsById.get(step.needs[0].from));
+    return extractStepOutput(outputsById.get(step.needs[0].from));
   }
   /** @type {Record<string, unknown>} */
   const data = {};
   for (const { alias, from } of step.needs) {
-    data[alias] = extractStepData(outputsById.get(from));
+    data[alias] = extractStepOutput(outputsById.get(from));
   }
   return data;
 }
@@ -263,34 +252,24 @@ export function mergeStepData(step, outputsById, triggerData) {
  * @returns {ParsedSetStep}
  */
 function parseSetStep(step) {
-  if (step.needs != null) {
-    throw new Error("needs is not allowed on set steps");
-  }
   const spec = step.set;
   if (spec == null || typeof spec !== "object" || Array.isArray(spec)) {
     throw new Error(`Invalid set step: ${JSON.stringify(step)}`);
   }
   const expression = spec.expression;
-  const as = spec.as;
   if (typeof expression !== "string" || !expression.trim()) {
     throw new Error("set.expression is required");
   }
-  if (typeof as !== "string" || !AS_IDENT.test(as)) {
-    throw new Error(`Invalid set.as: ${JSON.stringify(as)}`);
-  }
-  if (RESERVED_AS.has(as)) {
-    throw new Error(`set.as "${as}" is reserved`);
-  }
   compileJsonata(expression, "set.expression");
+  const { needsKind, needs } = parseNeeds(step.needs);
   return {
     kind: "set",
     script: SET_STEP_SCRIPT,
-    config: { expression, as },
+    config: { expression },
     expression,
-    as,
     id: parseOptionalId(step.id),
-    needsKind: "none",
-    needs: [],
+    needsKind,
+    needs,
     when: parseWhen(step.when),
   };
 }
diff --git a/packages/server/workflows/default/comic-monkeyuser-to-ntfy.yaml b/packages/server/workflows/default/comic-monkeyuser-to-ntfy.yaml
index c0161a2..dbc554e 100644
--- a/packages/server/workflows/default/comic-monkeyuser-to-ntfy.yaml
+++ b/packages/server/workflows/default/comic-monkeyuser-to-ntfy.yaml
@@ -10,7 +10,11 @@ scripts:
   - script: jsonata.js
     config:
       expression: |
-        {"data": {"title": httpResponse.title, "message": httpResponse.title, "attach": httpResponse.url}}
+        {
+          "title": data.httpResponse.title,
+          "message": data.httpResponse.title,
+          "attach": data.httpResponse.url
+        }
   - fetch-binary.js
   - script: ntfy.js
     config:
diff --git a/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml b/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml
index 32b05b4..b305130 100644
--- a/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml
+++ b/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml
@@ -13,11 +13,9 @@ scripts:
     config:
       expression: |
         {
-          "data": {
-            "title": item.title,
-            "message": item.contentSnippet & "\n" & item.link,
-            "attach": item.mediaContent.url ? item.mediaContent.url : (item.mediaContent.$ ? item.mediaContent.$.url : undefined)
-          }
+          "title": data.item.title,
+          "message": data.item.contentSnippet & "\n" & data.item.link,
+          "attach": data.item.mediaContent.url ? data.item.mediaContent.url : (data.item.mediaContent.$ ? data.item.mediaContent.$.url : undefined)
         }
   - script: ntfy.js
     config:
diff --git a/packages/server/workflows/default/send-gmail.yaml b/packages/server/workflows/default/send-gmail.yaml
index 0bddf4d..3673194 100644
--- a/packages/server/workflows/default/send-gmail.yaml
+++ b/packages/server/workflows/default/send-gmail.yaml
@@ -14,18 +14,16 @@ scripts:
     config:
       expression: |
         {
-          "data": {
-            "to": $exists(to) ? to : "nasyarobby@gmail.com",
-            "from": from,
-            "subject": subject,
-            "text": $exists(text) ? text : ($exists(body) ? body : message),
-            "html": html,
-            "cc": cc,
-            "bcc": bcc,
-            "replyTo": replyTo,
-            "priority": priority,
-            "headers": headers
-          }
+          "to": $exists(data.to) ? data.to : "nasyarobby@gmail.com",
+          "from": data.from,
+          "subject": data.subject,
+          "text": $exists(data.text) ? data.text : ($exists(data.body) ? data.body : data.message),
+          "html": data.html,
+          "cc": data.cc,
+          "bcc": data.bcc,
+          "replyTo": data.replyTo,
+          "priority": data.priority,
+          "headers": data.headers
         }
   - script: send-email.js
     config:
diff --git a/packages/server/workflows/default/test.yaml b/packages/server/workflows/default/test.yaml
index 871e1b7..4c1cb48 100644
--- a/packages/server/workflows/default/test.yaml
+++ b/packages/server/workflows/default/test.yaml
@@ -3,7 +3,7 @@ scripts:
   - get-current-time.js
   - script: jsonata.js
     config: 
-      expression: '{"data": {"message": datetime & " " & processId}}'
+      expression: '{"message": data.datetime & " " & data.processId}'
   - ntfy.js
 triggers:
   - type: HTTP
diff --git a/packages/server/workflows/default/time-and-comic-to-ntfy.yaml b/packages/server/workflows/default/time-and-comic-to-ntfy.yaml
index 640e683..4268411 100644
--- a/packages/server/workflows/default/time-and-comic-to-ntfy.yaml
+++ b/packages/server/workflows/default/time-and-comic-to-ntfy.yaml
@@ -19,11 +19,11 @@ scripts:
     needs: [time, comic]
     config:
       expression: |
-        {"data": {
-          "title": comic.httpResponse.title,
-          "message": time.datetime & " " & comic.httpResponse.title,
-          "attach": comic.httpResponse.url
-        }}
+        {
+          "title": data.comic.httpResponse.title,
+          "message": data.time.datetime & " " & data.comic.httpResponse.title,
+          "attach": data.comic.httpResponse.url
+        }
 
   - id: notify
     script: ntfy.js
diff --git a/packages/server/workflows/default/time-to-ntfy-example.yaml b/packages/server/workflows/default/time-to-ntfy-example.yaml
index 830c4e5..683d505 100644
--- a/packages/server/workflows/default/time-to-ntfy-example.yaml
+++ b/packages/server/workflows/default/time-to-ntfy-example.yaml
@@ -2,10 +2,10 @@ name: time to ntfy example
 description: |
   this workflow will send a message to ntfy with the current time
 scripts:
-  - get-current-time.js
+  - script: get-current-time.js
   - script: ntfy.js
     config:
-      url: https://ntfy.sh/scrunner
+      url: https://n.0dev.web.id/system
 triggers:
   - type: HTTP
     method: POST
diff --git a/packages/server/workflows/default/track.yaml b/packages/server/workflows/default/track.yaml
index e2f21a7..5593b67 100644
--- a/packages/server/workflows/default/track.yaml
+++ b/packages/server/workflows/default/track.yaml
@@ -16,10 +16,8 @@ scripts:
     config:
       expression: |
         {
-          "data": {
-            "title": httpResponse.customer_name,
-            "message": httpResponse.customer_name & " : " & httpResponse.status
-          }
+          "title": data.httpResponse.customer_name,
+          "message": data.httpResponse.customer_name & " : " & data.httpResponse.status
         }
   - script: ntfy.js
     config:
diff --git a/packages/web/src/api/hooks.js b/packages/web/src/api/hooks.js
index ec87e50..72f052c 100644
--- a/packages/web/src/api/hooks.js
+++ b/packages/web/src/api/hooks.js
@@ -107,11 +107,12 @@ export function useDeleteScript() {
 
 export function useDryRunScript() {
   return useMutation({
-    mutationFn: async ({ name, content, data, config, owner }) =>
+    mutationFn: async ({ name, content, data, context, config, owner }) =>
       (
         await api.post(`/scripts/${encodeURIComponent(name)}/dry-run`, {
           content,
           data,
+          context,
           config,
           owner,
         })
diff --git a/packages/web/src/components/ScriptMetaPanel.jsx b/packages/web/src/components/ScriptMetaPanel.jsx
index 8bdea86..2d915b2 100644
--- a/packages/web/src/components/ScriptMetaPanel.jsx
+++ b/packages/web/src/components/ScriptMetaPanel.jsx
@@ -1,4 +1,4 @@
-import { scriptTags } from "../lib/script.js";
+import { scriptTags, scriptReadsCtx } from "../lib/script.js";
 import { TagBadge } from "./TagBadge.jsx";
 
 function FieldTable({ title, fields }) {
@@ -64,17 +64,21 @@ export function ScriptMetaPanel({ meta, metaError, className = "" }) {
   return (
     <div className={`space-y-3 ${className}`}>
       {meta.description ? <p className="text-sm">{meta.description}</p> : null}
-      {tags.length ? (
+      {(tags.length || scriptReadsCtx(meta)) ? (
         <div className="flex flex-wrap gap-1">
           {tags.map((tag) => (
             <TagBadge key={tag} tag={tag} />
           ))}
+          {scriptReadsCtx(meta) ? (
+            <span className="badge badge-outline badge-sm font-mono">reads: ctx</span>
+          ) : null}
         </div>
       ) : null}
-      <div className="grid gap-3 md:grid-cols-3">
+      <div className="grid gap-3 md:grid-cols-2 xl:grid-cols-4">
         <FieldTable title="Config" fields={meta.config} />
         <FieldTable title="Input (data)" fields={meta.input} />
         <FieldTable title="Output" fields={meta.output} />
+        <FieldTable title="Context" fields={meta.context} />
       </div>
     </div>
   );
diff --git a/packages/web/src/components/workflow/AddScriptDialog.jsx b/packages/web/src/components/workflow/AddScriptDialog.jsx
index 8ed261c..8718f97 100644
--- a/packages/web/src/components/workflow/AddScriptDialog.jsx
+++ b/packages/web/src/components/workflow/AddScriptDialog.jsx
@@ -49,7 +49,9 @@ export function AddScriptDialog({ open, onClose, onPick }) {
               }}
             >
               <span className="font-semibold">Set (JSONata)</span>
-              <span className="text-xs opacity-70">Assign a JSONata result to a variable</span>
+              <span className="text-xs opacity-70">
+                JSONata over ctx; result becomes the next step’s data
+              </span>
             </button>
           </li>
           {isLoading ? (
diff --git a/packages/web/src/components/workflow/ScriptCard.jsx b/packages/web/src/components/workflow/ScriptCard.jsx
index 9aae03b..7148e36 100644
--- a/packages/web/src/components/workflow/ScriptCard.jsx
+++ b/packages/web/src/components/workflow/ScriptCard.jsx
@@ -42,10 +42,10 @@ export function ScriptCard({
     step.id && otherSteps.some((s) => s.id === step.id && s.uiId !== step.uiId);
   const preview = previewConfigValue(step.config, meta?.previewConfigKey);
   const previewFull = configValueText(step.config, meta?.previewConfigKey);
-  const baseName = step.kind === "set" ? `set:${step.as || "…"}` : step.script || "untitled";
+  const baseName = step.kind === "set" ? "set" : step.script || "untitled";
   const titleFull = previewFull ? `${baseName} (${previewFull})` : baseName;
   const setConfig =
-    step.kind === "set" ? { as: step.as ?? "", expression: step.expression ?? "" } : null;
+    step.kind === "set" ? { expression: step.expression ?? "" } : null;
 
   return (
     <article
@@ -95,7 +95,9 @@ export function ScriptCard({
               <p className="text-sm opacity-70 mt-1">{meta.description}</p>
             ) : null}
             {expanded && step.kind === "set" ? (
-              <p className="text-sm opacity-70 mt-1">Assign a JSONata result onto the context</p>
+              <p className="text-sm opacity-70 mt-1">
+                JSONata over ctx; result becomes the next step’s data
+              </p>
             ) : null}
           </button>
           {step.kind === "script" ? (
@@ -142,14 +144,11 @@ export function ScriptCard({
           <>
             {step.kind === "set" ? (
               <div className="space-y-2">
-                <FieldLabel name="as" required description="Context field to write (not data or config)" />
-                <input
-                  className="input input-sm w-full font-mono"
-                  value={step.as ?? ""}
-                  disabled={disabled}
-                  onChange={(e) => onChange({ ...step, as: e.target.value })}
+                <FieldLabel
+                  name="expression"
+                  required
+                  description="JSONata evaluated against ctx (data, context, config). Result becomes the next step's data."
                 />
-                <FieldLabel name="expression" required description="JSONata evaluated against ctx" />
                 <textarea
                   className="textarea textarea-sm w-full min-h-24 font-mono text-xs"
                   value={step.expression ?? ""}
@@ -186,14 +185,12 @@ export function ScriptCard({
                     <span className="text-error text-xs">Duplicate step id</span>
                   ) : null}
                 </label>
-                {step.kind === "set" ? null : (
-                  <NeedsEditor
-                    step={step}
-                    otherSteps={otherSteps}
-                    disabled={disabled}
-                    onChange={onChange}
-                  />
-                )}
+                <NeedsEditor
+                  step={step}
+                  otherSteps={otherSteps}
+                  disabled={disabled}
+                  onChange={onChange}
+                />
                 <label className="form-control">
                   <span className="label py-0 text-sm">when</span>
                   <input
@@ -244,7 +241,7 @@ function NeedsEditor({ step, otherSteps, disabled, onChange }) {
         disabled={disabled}
         onChange={(e) => setMode(e.target.value)}
       >
-        <option value="none">None (use previous step data)</option>
+        <option value="none">None (trigger data / previous output)</option>
         <option value="list">List of step ids</option>
         <option value="map">Map alias → step id</option>
       </select>
@@ -366,29 +363,46 @@ function needsMode(needs) {
 export function ScriptTryDialog({ script, config, meta, owner, onClose }) {
   const existing = useScript(script);
   const dryRun = useDryRunScript();
-  const defaultData = useMemo(() => prettyJson(contextFromMeta(meta).data ?? {}), [meta]);
+  const defaults = useMemo(() => contextFromMeta(meta), [meta]);
+  const defaultData = useMemo(() => prettyJson(defaults.data ?? {}), [defaults]);
+  const defaultContext = useMemo(() => prettyJson(defaults.context ?? {}), [defaults]);
   const [dataJson, setDataJson] = useState(defaultData);
+  const [contextJson, setContextJson] = useState(defaultContext);
   const [parseError, setParseError] = useState(null);
   const [expanded, setExpanded] = useState(false);
 
   useEffect(() => {
     setDataJson(defaultData);
-  }, [defaultData]);
+    setContextJson(defaultContext);
+  }, [defaultData, defaultContext]);
 
-  const outputJson = dryRun.data
-    ? prettyJson(dryRun.data.status === "success" ? dryRun.data.output : { error: dryRun.data.error })
+  const resultJson = dryRun.data
+    ? prettyJson(
+        dryRun.data.status === "success"
+          ? {
+              output: dryRun.data.output,
+              context: dryRun.data.context,
+              ...(dryRun.data.skipRemaining ? { skipRemaining: true } : {}),
+            }
+          : { error: dryRun.data.error },
+      )
     : "";
 
   function onRun() {
     setParseError(null);
     let data;
+    let context;
     try {
-      const parsed = JSON.parse(dataJson || "null");
-      data = parsed;
+      data = JSON.parse(dataJson || "null");
+      context = JSON.parse(contextJson || "{}");
     } catch (err) {
       setParseError(err instanceof Error ? err.message : String(err));
       return;
     }
+    if (context != null && (typeof context !== "object" || Array.isArray(context))) {
+      setParseError("context must be a JSON object");
+      return;
+    }
     if (!existing.data?.content) {
       setParseError("could not load script source");
       return;
@@ -397,6 +411,7 @@ export function ScriptTryDialog({ script, config, meta, owner, onClose }) {
       name: script,
       content: existing.data.content,
       data,
+      context: context ?? {},
       config: config ?? {},
       owner,
     });
@@ -442,12 +457,18 @@ export function ScriptTryDialog({ script, config, meta, owner, onClose }) {
             </div>
           </div>
           <div className={expanded ? "min-h-0 flex-1 h-full" : "h-48"}>
+            <p className="text-xs opacity-60 mb-1">context</p>
+            <div className={expanded ? "h-[calc(100%-1.25rem)]" : "h-full"}>
+              <CodeEditor language="json" value={contextJson} onChange={setContextJson} height="100%" />
+            </div>
+          </div>
+          <div className={`md:col-span-2 ${expanded ? "min-h-0 flex-1 h-full" : "h-48"}`}>
             <p className="text-xs opacity-60 mb-1 flex items-center gap-2">
-              output
+              result (output + context)
               {dryRun.data?.status ? <StatusBadge status={dryRun.data.status} /> : null}
             </p>
             <div className={expanded ? "h-[calc(100%-1.25rem)]" : "h-full"}>
-              <CodeEditor language="json" value={outputJson} onChange={() => {}} readOnly height="100%" />
+              <CodeEditor language="json" value={resultJson} onChange={() => {}} readOnly height="100%" />
             </div>
           </div>
         </div>
diff --git a/packages/web/src/components/workflow/ScriptsTab.jsx b/packages/web/src/components/workflow/ScriptsTab.jsx
index f678110..5770a9b 100644
--- a/packages/web/src/components/workflow/ScriptsTab.jsx
+++ b/packages/web/src/components/workflow/ScriptsTab.jsx
@@ -62,7 +62,8 @@ export function ScriptsTab({
     <div className="flex min-h-0 flex-1 flex-col gap-3 overflow-auto">
       <div className="flex shrink-0 items-center justify-between">
         <p className="text-sm opacity-70">
-          Steps run top to bottom (or by needs in DAG mode). Drag the handle to reorder.
+          Steps run top to bottom. In DAG mode, <span className="font-mono">needs</span> selects
+          upstream outputs as this step’s data; context is shared per wave.
         </p>
         <button
           type="button"
diff --git a/packages/web/src/lib/script.js b/packages/web/src/lib/script.js
index fc64322..c8dd7aa 100644
--- a/packages/web/src/lib/script.js
+++ b/packages/web/src/lib/script.js
@@ -1,5 +1,5 @@
 export const NEW_SCRIPT_TEMPLATE = `async function main(ctx) {
-  return ctx;
+  return { output: ctx.data ?? null, context: ctx.context ?? {} };
 }
 
 main.meta = {
@@ -9,8 +9,10 @@ main.meta = {
   config: {},
   input: {},
   output: {},
+  context: {},
   example: {
     data: {},
+    context: {},
     config: {},
   },
 };
@@ -20,6 +22,7 @@ export default main;
 
 export const DEFAULT_INPUT_CONTEXT = `{
   "data": {},
+  "context": {},
   "config": {}
 }
 `;
@@ -35,6 +38,10 @@ export function scriptTags(meta) {
   return meta.tags.map((t) => String(t).trim()).filter(Boolean);
 }
 
+export function scriptReadsCtx(meta) {
+  return meta?.reads === "ctx";
+}
+
 const TAG_PALETTE = [
   { bg: "color-mix(in oklab, #2563eb 22%, transparent)", text: "#2563eb" },
   { bg: "color-mix(in oklab, #059669 22%, transparent)", text: "#059669" },
@@ -94,11 +101,13 @@ export function contextFromMeta(meta) {
   if (meta?.example && typeof meta.example === "object" && !Array.isArray(meta.example)) {
     return {
       data: "data" in meta.example ? meta.example.data : {},
+      context: "context" in meta.example ? meta.example.context ?? {} : {},
       config: "config" in meta.example ? meta.example.config ?? {} : {},
     };
   }
   return {
     data: defaultsFromFields(meta?.input),
+    context: defaultsFromFields(meta?.context),
     config: defaultsFromFields(meta?.config),
   };
 }
diff --git a/packages/web/src/lib/workflow-doc.js b/packages/web/src/lib/workflow-doc.js
index 100c770..b280318 100644
--- a/packages/web/src/lib/workflow-doc.js
+++ b/packages/web/src/lib/workflow-doc.js
@@ -96,7 +96,6 @@ export function newSetStep() {
     uiId: nextUiId("step"),
     kind: "set",
     script: "set",
-    as: "value",
     expression: "",
     id: "",
     when: "",
@@ -187,11 +186,10 @@ function normalizeStep(step) {
       uiId,
       kind: "set",
       script: "set",
-      as: typeof spec.as === "string" ? spec.as : "",
       expression: typeof spec.expression === "string" ? spec.expression : "",
       id: typeof step.id === "string" ? step.id : "",
       when: typeof step.when === "string" ? step.when : "",
-      needs: null,
+      needs: step.needs ?? null,
     };
   }
   const known = new Set(["script", "config", "id", "when", "needs", "set"]);
@@ -254,9 +252,9 @@ function dumpStep(step) {
     if (step.id) out.id = step.id;
     out.set = {
       expression: step.expression ?? "",
-      as: step.as ?? "",
     };
     if (step.when) out.when = step.when;
+    if (step.needs != null && !isEmptyNeeds(step.needs)) out.needs = step.needs;
     return out;
   }
   /** @type {Record<string, unknown>} */
diff --git a/packages/web/src/lib/workflow-mermaid.js b/packages/web/src/lib/workflow-mermaid.js
index 39d2027..740fcc0 100644
--- a/packages/web/src/lib/workflow-mermaid.js
+++ b/packages/web/src/lib/workflow-mermaid.js
@@ -1,15 +1,13 @@
 function parseStep(step) {
   if (typeof step === "string") {
-    return { kind: "script", script: step, id: null, needs: null, when: null, as: null };
+    return { kind: "script", script: step, id: null, needs: null, when: null };
   }
   if (step?.set) {
-    const as = typeof step.set?.as === "string" && step.set.as ? step.set.as : "set";
     return {
       kind: "set",
       script: null,
-      as,
       id: typeof step.id === "string" && step.id ? step.id : null,
-      needs: null,
+      needs: step.needs ?? null,
       when: typeof step.when === "string" && step.when ? step.when : null,
     };
   }
@@ -17,7 +15,6 @@ function parseStep(step) {
     return {
       kind: "script",
       script: step.script,
-      as: null,
       id: typeof step.id === "string" && step.id ? step.id : null,
       needs: step.needs ?? null,
       when: typeof step.when === "string" && step.when ? step.when : null,
@@ -55,7 +52,7 @@ function triggerLabel(t) {
 
 function stepLabel(s) {
   if (s.kind === "set") {
-    const base = s.id ? `${s.id}: set ${s.as}` : `set ${s.as}`;
+    const base = s.id ? `${s.id}: set` : "set";
     return s.when ? `${base} when: ${s.when}` : base;
   }
   const base = s.id ? `${s.id}: ${s.script}` : s.script;
diff --git a/packages/web/src/pages/EventDetailPage.jsx b/packages/web/src/pages/EventDetailPage.jsx
index bd453aa..372005a 100644
--- a/packages/web/src/pages/EventDetailPage.jsx
+++ b/packages/web/src/pages/EventDetailPage.jsx
@@ -1,14 +1,13 @@
-import { useMemo, useState } from "react";
+import { useMemo, useState, Fragment } from "react";
 import { Link, useNavigate, useParams } from "react-router-dom";
 import { LuArrowLeft, LuFilter } from "react-icons/lu";
 import { useRun } from "../api/hooks.js";
 import { LogViewer } from "../components/LogViewer.jsx";
 import { formatTime, StatusBadge } from "../lib/format.jsx";
+import { prettyJson } from "../lib/script.js";
 
 function stepLabel(s) {
-  if (s.script === "set") {
-    return s.config?.as ? `set:${s.config.as}` : "set";
-  }
+  if (s.script === "set") return "set";
   return s.script;
 }
 
@@ -20,11 +19,39 @@ function isEditableScript(s) {
   return Boolean(s.script) && s.script !== "set";
 }
 
+function JsonBlock({ title, value }) {
+  if (value == null || value === "") return null;
+  const text = prettyJson(value);
+  if (!text) return null;
+  return (
+    <details className="collapse collapse-arrow border border-base-300 bg-base-100">
+      <summary className="collapse-title min-h-0 py-2 text-sm font-semibold">{title}</summary>
+      <div className="collapse-content">
+        <pre className="max-h-80 overflow-auto rounded-box bg-base-200 p-3 font-mono text-xs">
+          {text}
+        </pre>
+      </div>
+    </details>
+  );
+}
+
+function envelopeParts(raw) {
+  if (raw != null && typeof raw === "object" && !Array.isArray(raw) && ("output" in raw || "context" in raw)) {
+    return {
+      output: "output" in raw ? raw.output : undefined,
+      context: "context" in raw ? raw.context : undefined,
+      skipRemaining: raw.skipRemaining === true,
+    };
+  }
+  return { output: raw, context: undefined, skipRemaining: false };
+}
+
 export function EventDetailPage() {
   const { id } = useParams();
   const navigate = useNavigate();
   const { data: run, isLoading, error } = useRun(id);
   const [stepFilters, setStepFilters] = useState([]);
+  const [openStep, setOpenStep] = useState(null);
 
   function goBack() {
     const idx = window.history.state?.idx;
@@ -60,6 +87,8 @@ export function EventDetailPage() {
   if (isLoading) return <span className="loading loading-spinner loading-lg" />;
   if (error || !run) return <p className="text-error">Event not found</p>;
 
+  const runParts = envelopeParts(run.output);
+
   return (
     <div className="space-y-4">
       <div className="flex items-center gap-2">
@@ -98,6 +127,15 @@ export function EventDetailPage() {
         </div>
       ) : null}
 
+      <div className="grid gap-2 sm:grid-cols-2">
+        <JsonBlock title="Run input (data)" value={run.input} />
+        <JsonBlock title="Run output" value={runParts.output} />
+        <JsonBlock title="Run context" value={runParts.context} />
+      </div>
+      {runParts.skipRemaining ? (
+        <p className="text-sm opacity-70">This run stopped early (<span className="font-mono">skipRemaining</span>).</p>
+      ) : null}
+
       <section>
         <h2 className="font-semibold mb-2">Steps</h2>
         <div className="overflow-x-auto">
@@ -113,42 +151,65 @@ export function EventDetailPage() {
               </tr>
             </thead>
             <tbody>
-              {steps.map((s) => (
-                <tr key={s.id}>
-                  <td>{s.step_index}</td>
-                  <td className="font-mono">
-                    {isEditableScript(s) ? (
-                      <Link className="link" to={`/scripts/${encodeURIComponent(s.script)}/edit`}>
-                        {stepLabel(s)}
-                      </Link>
-                    ) : (
-                      stepLabel(s)
-                    )}
-                  </td>
-                  <td>
-                    <StatusBadge status={s.status} />
-                  </td>
-                  <td>{s.duration_ms != null ? `${s.duration_ms}ms` : "—"}</td>
-                  <td
-                    className={
-                      s.status === "skipped" ? "opacity-60 text-xs" : "text-error text-xs"
-                    }
-                  >
-                    {s.error || ""}
-                  </td>
-                  <td className="text-right">
-                    <button
-                      type="button"
-                      className={`btn btn-ghost btn-xs btn-square ${stepFilters.includes(s.id) ? "btn-active" : ""}`}
-                      aria-label={`Filter logs for ${filterLabel(s)}`}
-                      aria-pressed={stepFilters.includes(s.id)}
-                      onClick={() => toggleStepFilter(s.id)}
-                    >
-                      <LuFilter className="size-3.5" />
-                    </button>
-                  </td>
-                </tr>
-              ))}
+              {steps.map((s) => {
+                const parts = envelopeParts(s.output);
+                const open = openStep === s.id;
+                return (
+                  <Fragment key={s.id}>
+                    <tr>
+                      <td>{s.step_index}</td>
+                      <td className="font-mono">
+                        {isEditableScript(s) ? (
+                          <Link className="link" to={`/scripts/${encodeURIComponent(s.script)}/edit`}>
+                            {stepLabel(s)}
+                          </Link>
+                        ) : (
+                          stepLabel(s)
+                        )}
+                      </td>
+                      <td>
+                        <StatusBadge status={s.status} />
+                      </td>
+                      <td>{s.duration_ms != null ? `${s.duration_ms}ms` : "—"}</td>
+                      <td
+                        className={
+                          s.status === "skipped" ? "opacity-60 text-xs" : "text-error text-xs"
+                        }
+                      >
+                        {s.error || (parts.skipRemaining ? "skipRemaining" : "")}
+                      </td>
+                      <td className="text-right">
+                        <button
+                          type="button"
+                          className="btn btn-ghost btn-xs"
+                          onClick={() => setOpenStep(open ? null : s.id)}
+                        >
+                          I/O
+                        </button>
+                        <button
+                          type="button"
+                          className={`btn btn-ghost btn-xs btn-square ${stepFilters.includes(s.id) ? "btn-active" : ""}`}
+                          aria-label={`Filter logs for ${filterLabel(s)}`}
+                          aria-pressed={stepFilters.includes(s.id)}
+                          onClick={() => toggleStepFilter(s.id)}
+                        >
+                          <LuFilter className="size-3.5" />
+                        </button>
+                      </td>
+                    </tr>
+                    {open ? (
+                      <tr>
+                        <td colSpan={6} className="bg-base-200">
+                          <div className="grid gap-2 p-2 sm:grid-cols-2">
+                            <JsonBlock title="output" value={parts.output} />
+                            <JsonBlock title="context" value={parts.context} />
+                          </div>
+                        </td>
+                      </tr>
+                    ) : null}
+                  </Fragment>
+                );
+              })}
             </tbody>
           </table>
         </div>
diff --git a/packages/web/src/pages/ScriptDryRunPage.jsx b/packages/web/src/pages/ScriptDryRunPage.jsx
index 58f459d..ddc332a 100644
--- a/packages/web/src/pages/ScriptDryRunPage.jsx
+++ b/packages/web/src/pages/ScriptDryRunPage.jsx
@@ -76,7 +76,9 @@ export function ScriptDryRunPage() {
     setRunStatus(lastRun.status);
     setLogs(lastRun.logs ?? []);
     if (lastRun.status === "success") {
-      setOutputJson(prettyJson(lastRun.output));
+      const envelope = { output: lastRun.output, context: lastRun.context };
+      if (lastRun.skipRemaining) envelope.skipRemaining = true;
+      setOutputJson(prettyJson(envelope));
     } else {
       setOutputJson(prettyJson({ error: lastRun.error ?? "run failed" }));
     }
@@ -97,10 +99,11 @@ export function ScriptDryRunPage() {
       throw new Error(err instanceof Error ? err.message : "invalid JSON");
     }
     if (parsed == null || typeof parsed !== "object" || Array.isArray(parsed)) {
-      throw new Error('input context must be a JSON object with "data" and/or "config"');
+      throw new Error('input must be a JSON object with "data", "context", and/or "config"');
     }
     return {
       data: "data" in parsed ? parsed.data : null,
+      context: "context" in parsed ? parsed.context : {},
       config: "config" in parsed ? parsed.config : null,
     };
   }
@@ -119,6 +122,7 @@ export function ScriptDryRunPage() {
       name,
       content,
       data: ctx.data,
+      context: ctx.context,
       config: ctx.config,
       owner,
     });
@@ -229,7 +233,7 @@ export function ScriptDryRunPage() {
         </section>
 
         <section className="flex min-h-0 flex-col gap-1">
-          <h2 className="shrink-0 text-sm font-semibold opacity-70">Output</h2>
+          <h2 className="shrink-0 text-sm font-semibold opacity-70">Result (output + context)</h2>
           <div className="min-h-0 flex-1">
             <CodeEditor
               language="json"