diff --git a/packages/server/kv-store.js b/packages/server/kv-store.js
index 57cd5cf..f1dfcb3 100644
--- a/packages/server/kv-store.js
+++ b/packages/server/kv-store.js
@@ -257,6 +257,80 @@ export async function kvList(namespace, opts = {}) {
   return items;
 }
 
+function escapeLike(value) {
+  return value.replaceAll("\\", "\\\\").replaceAll("%", "\\%").replaceAll("_", "\\_");
+}
+
+async function pruneExpiredKv() {
+  await db("script_state")
+    .whereNotNull("expires_at")
+    .andWhere("expires_at", "<=", nowIso())
+    .del();
+}
+
+/**
+ * @param {{
+ *   namespace?: string,
+ *   q?: string,
+ *   limit?: number,
+ *   offset?: number,
+ * }} [opts]
+ */
+export async function kvQuery(opts = {}) {
+  await pruneExpiredKv();
+
+  const limit = Math.min(Math.max(opts.limit ?? 50, 1), 100);
+  const offset = Math.max(Number(opts.offset) || 0, 0);
+
+  let q = db("script_state");
+  if (opts.namespace) {
+    assertNamespace(opts.namespace);
+    q = q.where({ namespace: opts.namespace });
+  }
+  if (typeof opts.q === "string" && opts.q.length > 0) {
+    const like = `%${escapeLike(opts.q)}%`;
+    q = q.where(function likeSearch() {
+      this.whereRaw("key LIKE ? ESCAPE '\\'", [like]).orWhereRaw(
+        "value LIKE ? ESCAPE '\\'",
+        [like],
+      );
+    });
+  }
+
+  const countRow = await q.clone().count({ count: "*" }).first();
+  const total = Number(countRow?.count ?? 0);
+
+  const rows = await q
+    .clone()
+    .orderBy("updated_at", "desc")
+    .orderBy("namespace", "asc")
+    .orderBy("key", "asc")
+    .limit(limit)
+    .offset(offset);
+
+  return {
+    items: rows.map((row) => ({
+      namespace: row.namespace,
+      key: row.key,
+      value: deserializeKvValue(row.value),
+      updatedAt: row.updated_at,
+      expiresAt: row.expires_at ?? null,
+    })),
+    total,
+    limit,
+    offset,
+  };
+}
+
+/**
+ * @returns {Promise<string[]>}
+ */
+export async function kvNamespaces() {
+  await pruneExpiredKv();
+  const rows = await db("script_state").distinct("namespace").orderBy("namespace", "asc");
+  return rows.map((row) => row.namespace);
+}
+
 /**
  * @param {string} defaultNamespace
  */
diff --git a/packages/server/registry.js b/packages/server/registry.js
index f0ab7c0..43c6eee 100644
--- a/packages/server/registry.js
+++ b/packages/server/registry.js
@@ -260,6 +260,36 @@ 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 {string} runId
+   * @param {import("pino").Logger} runLog
+   * @param {string} reason
+   */
+  async function markStepSkipped(parsed, index, ctx, runId, runLog, reason) {
+    const script = parsed.kind === "set" ? SET_STEP_SCRIPT : parsed.script;
+    const step = await store.startStep({
+      runId,
+      index,
+      script,
+      config: parsed.config,
+    });
+    const stepLog = runLog.child({ stepId: step.id, script });
+    stepLog.debug({ reason }, "step skipped");
+    await store.finishStep(step.id, "skipped", ctx, reason);
+  }
+
   /**
    * @param {import("./workflow-parse.js").CompiledScripts} compiled
    * @param {{ data?: unknown }} ctx
@@ -271,7 +301,8 @@ export function createRegistry(server) {
    */
   async function runLinearSteps(compiled, ctx, runId, runLog, key, owner, depth) {
     let next = ctx;
-    for (const index of compiled.order) {
+    for (let i = 0; i < compiled.order.length; i++) {
+      const index = compiled.order[i];
       const parsed = compiled.steps[index];
       next = await runCompiledStep(
         parsed,
@@ -283,6 +314,20 @@ export function createRegistry(server) {
         owner,
         depth,
       );
+      if (isSkipRemaining(next)) {
+        for (let j = i + 1; j < compiled.order.length; j++) {
+          const laterIndex = compiled.order[j];
+          await markStepSkipped(
+            compiled.steps[laterIndex],
+            laterIndex,
+            next,
+            runId,
+            runLog,
+            "skipRemaining",
+          );
+        }
+        break;
+      }
     }
     return next;
   }
@@ -318,6 +363,20 @@ export function createRegistry(server) {
       if (parsed.id) {
         outputsById.set(parsed.id, last);
       }
+      if (isSkipRemaining(last)) {
+        for (let j = orderIndex + 1; j < compiled.order.length; j++) {
+          const laterParsed = compiled.steps[compiled.order[j]];
+          await markStepSkipped(
+            laterParsed,
+            j,
+            last,
+            runId,
+            runLog,
+            "skipRemaining",
+          );
+        }
+        break;
+      }
     }
     return last;
   }
@@ -389,7 +448,7 @@ export function createRegistry(server) {
         const whenResult = await evaluateJsonata(parsed.when, ctx);
         if (!isJsonataTruthy(whenResult)) {
           stepLog.debug({ when: parsed.when }, "step skipped");
-          await store.finishStep(step.id, "skipped", ctx);
+          await store.finishStep(step.id, "skipped", ctx, "when condition");
           return ctx;
         }
       }
diff --git a/packages/server/runner.js b/packages/server/runner.js
index 77fb5cc..5e4584a 100644
--- a/packages/server/runner.js
+++ b/packages/server/runner.js
@@ -16,6 +16,7 @@ import workflowsPluginFactory from "./src/api/workflows.js";
 import runsPlugin from "./src/api/runs.js";
 import dashboardPluginFactory from "./src/api/dashboard.js";
 import secretsPlugin from "./src/api/secrets.js";
+import kvPlugin from "./src/api/kv.js";
 import { WEB_DIST } from "./paths.js";
 import { resolveSecretsKeyMaterial } from "./secrets.js";
 
@@ -88,6 +89,7 @@ await server.register(
     await api.register(authPlugin);
     await api.register(usersPlugin);
     await api.register(secretsPlugin);
+    await api.register(kvPlugin);
     await api.register(scriptsPluginFactory(registry));
     await api.register(workflowsPluginFactory(registry));
     await api.register(runsPlugin);
diff --git a/packages/server/script-fingerprint.js b/packages/server/script-fingerprint.js
new file mode 100644
index 0000000..f370c16
--- /dev/null
+++ b/packages/server/script-fingerprint.js
@@ -0,0 +1,183 @@
+import { createHash } from "node:crypto";
+
+const MAX_AGE_RE = /^(\d+(?:\.\d+)?)(s|m|h|d)$/i;
+const UNIT_MS = { s: 1000, m: 60_000, h: 3_600_000, d: 86_400_000 };
+
+/**
+ * @param {unknown} maxAge
+ * @returns {number | null}
+ */
+export function parseMaxAge(maxAge) {
+  if (maxAge == null || maxAge === false || maxAge === "") return null;
+  if (typeof maxAge === "number") {
+    if (!Number.isFinite(maxAge) || maxAge < 0) {
+      throw new Error("maxAge must be a non-negative number of milliseconds");
+    }
+    return maxAge;
+  }
+  if (typeof maxAge === "string") {
+    const trimmed = maxAge.trim();
+    if (trimmed === "") return null;
+    if (!/[a-z]/i.test(trimmed)) {
+      const asNum = Number(trimmed);
+      if (!Number.isFinite(asNum) || asNum < 0) {
+        throw new Error(`invalid maxAge: ${JSON.stringify(maxAge)}`);
+      }
+      return asNum;
+    }
+    const match = trimmed.match(MAX_AGE_RE);
+    if (!match) {
+      throw new Error(`invalid maxAge: ${JSON.stringify(maxAge)}`);
+    }
+    return Number(match[1]) * UNIT_MS[match[2].toLowerCase()];
+  }
+  throw new Error(`invalid maxAge: ${JSON.stringify(maxAge)}`);
+}
+
+function isBytes(value) {
+  return Buffer.isBuffer(value) || value instanceof Uint8Array;
+}
+
+/**
+ * @param {unknown} value
+ */
+export function canonicalize(value) {
+  if (value === undefined) return null;
+  if (isBytes(value)) return { $bytes: value.length };
+  if (value === null) return null;
+  if (typeof value !== "object") return value;
+  if (Array.isArray(value)) return value.map(canonicalize);
+  if (value instanceof Date) return value.toISOString();
+  /** @type {Record<string, unknown>} */
+  const out = {};
+  for (const key of Object.keys(value).sort()) {
+    out[key] = canonicalize(value[key]);
+  }
+  return out;
+}
+
+/**
+ * @param {unknown} value
+ */
+export function hashFingerprint(value) {
+  return createHash("sha256").update(JSON.stringify(canonicalize(value))).digest("hex");
+}
+
+/**
+ * @param {unknown} stored
+ * @returns {{ hash: string | null, at: string | null } | null}
+ */
+export function parseFingerprintRecord(stored) {
+  if (stored == null) return null;
+  if (typeof stored === "string" && stored.length > 0) {
+    return { hash: stored, at: null };
+  }
+  if (stored && typeof stored === "object" && !Array.isArray(stored)) {
+    const hash = /** @type {{ hash?: unknown }} */ (stored).hash;
+    const at = /** @type {{ at?: unknown }} */ (stored).at;
+    if (typeof hash === "string" && hash.length > 0) {
+      return { hash, at: typeof at === "string" && at.length > 0 ? at : null };
+    }
+  }
+  return { hash: null, at: null };
+}
+
+function ageMs(at, now = Date.now()) {
+  if (at == null) return null;
+  const t = Date.parse(at);
+  if (Number.isNaN(t)) return null;
+  return now - t;
+}
+
+function isAgeExpired(record, maxAgeMs, now) {
+  if (maxAgeMs == null || !record) return false;
+  if (record.at == null) return true;
+  const age = ageMs(record.at, now);
+  if (age == null) return true;
+  return age >= maxAgeMs;
+}
+
+function inspect(stored, hash, maxAgeMs, now = Date.now()) {
+  const previous = parseFingerprintRecord(stored);
+  const previousAt = previous?.at ?? null;
+  const age = ageMs(previousAt, now);
+  const hashChanged = !previous || previous.hash !== hash;
+  const expired = Boolean(previous) && !hashChanged && isAgeExpired(previous, maxAgeMs, now);
+  return {
+    hash,
+    previous: previous?.hash ?? null,
+    previousAt,
+    ageMs: age,
+    changed: hashChanged || expired,
+    expired,
+  };
+}
+
+/**
+ * @param {ReturnType<import("./kv-store.js").createKvApi>} kv
+ */
+export function createFingerprintApi(kv) {
+  return {
+    hash(value) {
+      return hashFingerprint(value);
+    },
+
+    /**
+     * @param {string} key
+     * @param {unknown} value
+     * @param {{ maxAge?: unknown }} [opts]
+     */
+    async check(key, value, opts = {}) {
+      const maxAgeMs = parseMaxAge(opts.maxAge);
+      const hash = hashFingerprint(value);
+      const stored = await kv.get(key);
+      return inspect(stored, hash, maxAgeMs);
+    },
+
+    /**
+     * @param {string} key
+     * @param {string} hash
+     */
+    async remember(key, hash) {
+      if (typeof hash !== "string" || hash.length === 0) {
+        throw new Error("fingerprint hash is required");
+      }
+      const record = { hash, at: new Date().toISOString() };
+      await kv.set(key, record);
+      return record;
+    },
+
+    /**
+     * @param {string} key
+     * @param {unknown} value
+     * @param {{ maxAge?: unknown }} [opts]
+     */
+    async claim(key, value, opts = {}) {
+      const maxAgeMs = parseMaxAge(opts.maxAge);
+      const hash = hashFingerprint(value);
+      const stored = await kv.get(key);
+      const result = inspect(stored, hash, maxAgeMs);
+
+      if (!result.changed) {
+        return { ...result, at: result.previousAt };
+      }
+
+      const next = { hash, at: new Date().toISOString() };
+      const cas = await kv.compareAndSet(key, stored ?? null, next);
+      if (!cas.ok) {
+        const again = inspect(cas.previous, hash, maxAgeMs);
+        if (!again.changed) {
+          return { ...again, at: again.previousAt };
+        }
+        return {
+          ...again,
+          changed: false,
+          expired: false,
+          at: again.previousAt,
+        };
+      }
+
+      return { ...result, at: next.at };
+    },
+  };
+}
diff --git a/packages/server/script-sandbox.js b/packages/server/script-sandbox.js
index c994e86..ee5f662 100644
--- a/packages/server/script-sandbox.js
+++ b/packages/server/script-sandbox.js
@@ -5,6 +5,7 @@ import { createRequire } from "node:module";
 import axios from "axios";
 import pino from "pino";
 import { createKvApi } from "./kv-store.js";
+import { createFingerprintApi } from "./script-fingerprint.js";
 import { SCRIPTS_DIR } from "./paths.js";
 import { isSecret, Secret, unwrapSecretsDeep } from "./secret-value.js";
 import { getSecretPlaintext } from "./secrets-store.js";
@@ -342,6 +343,7 @@ function createScriptSandbox({
   const scriptLog = log.child({ workflow: workflowName, script });
   const $axios = createScreenedAxios(scriptLog);
   const $kv = createKvApi(workflowName);
+  const $fingerprint = createFingerprintApi($kv);
   const $secrets = createSecretsApi(owner);
   const sandbox = {
     ...pickBuiltins(),
@@ -349,6 +351,7 @@ function createScriptSandbox({
     console: createConsole(scriptLog),
     $axios,
     $kv,
+    $fingerprint,
     $secrets,
     $workflows,
     require: createRestrictedRequire($axios),
diff --git a/packages/server/scripts/fingerprint.js b/packages/server/scripts/fingerprint.js
new file mode 100644
index 0000000..b02424c
--- /dev/null
+++ b/packages/server/scripts/fingerprint.js
@@ -0,0 +1,99 @@
+import jsonata from "jsonata";
+
+function ensureDataObject(ctx) {
+  if (ctx.data == null || typeof ctx.data !== "object" || Array.isArray(ctx.data)) {
+    ctx.data = {};
+  }
+}
+
+async function fingerprint(ctx) {
+  const key =
+    typeof ctx.config?.key === "string" && ctx.config.key.length > 0
+      ? ctx.config.key
+      : "fingerprint";
+  const jsonataExpr = ctx.config?.jsonata;
+  const skipRemaining = ctx.config?.skipRemaining !== false;
+
+  let source;
+  if (typeof jsonataExpr === "string" && jsonataExpr.length > 0) {
+    log.info({ jsonata: jsonataExpr }, "fingerprint: evaluating jsonata");
+    const expression = jsonata(jsonataExpr);
+    source = await expression.evaluate(ctx);
+  } else {
+    source = ctx.data;
+  }
+
+  log.info({ key }, "fingerprint: claiming");
+  const result = await $fingerprint.claim(key, source, {
+    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;
+
+  log.info(
+    {
+      key,
+      changed: result.changed,
+      expired: result.expired,
+      ageMs: result.ageMs,
+    },
+    "fingerprint: result",
+  );
+
+  if (!result.changed && skipRemaining) {
+    ctx.skipRemaining = true;
+  }
+
+  return ctx;
+}
+
+fingerprint.meta = {
+  description:
+    "Hash a value, compare it to the last stored fingerprint, and skip remaining steps when unchanged",
+  config: {
+    key: {
+      type: "string",
+      default: "fingerprint",
+      description: "KV key for the stored fingerprint record",
+    },
+    jsonata: {
+      type: "string",
+      required: false,
+      description: "JSONata against ctx; omitted hashes ctx.data",
+    },
+    skipRemaining: {
+      type: "boolean",
+      default: true,
+      description: "Skip later steps when the fingerprint is unchanged",
+    },
+    maxAge: {
+      type: "string",
+      required: false,
+      description: "Optional age limit (e.g. 24h, 7d, or milliseconds). Older matching hashes fire again",
+    },
+  },
+  input: {},
+  output: {
+    fingerprint: { type: "string", description: "SHA-256 hex of the source value" },
+    fingerprintChanged: { type: "boolean" },
+    fingerprintPrevious: { type: "string", required: false },
+    fingerprintAt: { type: "string", required: false, description: "ISO timestamp of the stored record" },
+    fingerprintAge: { type: "number", required: false, description: "Age in milliseconds" },
+    fingerprintExpired: { type: "boolean" },
+  },
+  example: {
+    data: { item: { guid: "https://example.com/post-1" } },
+    config: {
+      key: "latest-item",
+      jsonata: "data.item.guid ? data.item.guid : data.item.link",
+    },
+  },
+};
+
+export default fingerprint;
diff --git a/packages/server/scripts/ntfy.js b/packages/server/scripts/ntfy.js
index 635bfc0..7555ce8 100644
--- a/packages/server/scripts/ntfy.js
+++ b/packages/server/scripts/ntfy.js
@@ -1,3 +1,5 @@
+import jsonata from "jsonata";
+
 function ntfyHeaders(ctx) {
   const headers = {};
 
@@ -9,6 +11,32 @@ function ntfyHeaders(ctx) {
   return headers;
 }
 
+function resolveFingerprintKey(config) {
+  const fingerprint = config?.fingerprint;
+  if (fingerprint === true) return "fingerprint:ntfy";
+  if (typeof fingerprint === "string" && fingerprint.length > 0) return fingerprint;
+  return null;
+}
+
+function defaultFingerprintSource(ctx) {
+  return {
+    title: ctx.data?.title,
+    message: ctx.data?.message,
+    attach: ctx.data?.attach,
+    filename: ctx.data?.filename,
+    contentType: ctx.data?.contentType,
+  };
+}
+
+async function resolveFingerprintValue(ctx) {
+  const expr = ctx.config?.fingerprintJsonata;
+  if (typeof expr === "string" && expr.length > 0) {
+    const expression = jsonata(expr);
+    return await expression.evaluate(ctx);
+  }
+  return defaultFingerprintSource(ctx);
+}
+
 async function ntfy(ctx) {
   const file = ctx.data?.file;
   const hasFile = Buffer.isBuffer(file) || file instanceof Uint8Array;
@@ -25,6 +53,35 @@ async function ntfy(ctx) {
     "ntfy incoming context",
   );
 
+  const fingerprintKey = resolveFingerprintKey(ctx.config);
+  /** @type {{ hash: string, previousAt: string | null, ageMs: number | null } | null} */
+  let fp = null;
+
+  if (fingerprintKey) {
+    const source = await resolveFingerprintValue(ctx);
+    const checked = await $fingerprint.check(fingerprintKey, source, {
+      maxAge: ctx.config?.fingerprintMaxAge,
+    });
+    if (!checked.changed) {
+      log.info(
+        {
+          key: fingerprintKey,
+          fingerprint: checked.hash,
+          ageMs: checked.ageMs,
+        },
+        "ntfy: skipped, fingerprint unchanged",
+      );
+      return {
+        sent: "false",
+        skipped: true,
+        fingerprint: checked.hash,
+        fingerprintAt: checked.previousAt,
+        fingerprintAge: checked.ageMs,
+      };
+    }
+    fp = checked;
+  }
+
   const headers = ntfyHeaders(ctx);
   const ntfyUrl = ctx.config?.url || "https://ntfy.sh/scrunner";
 
@@ -47,22 +104,29 @@ async function ntfy(ctx) {
       maxBodyLength: Infinity,
       maxContentLength: Infinity,
     });
-    return { sent: "true" };
+  } else {
+    if (ctx.data?.attach) {
+      log.info("ntfy: setting attach %s", ctx.data.attach);
+      headers.Attach = ctx.data.attach;
+    }
+
+    const truncatedMessage = ctx.data?.message?.substring(0, 100);
+    log.info("ntfy sending message to %s", ntfyUrl);
+    log.info("ntfy messsage: %s", truncatedMessage);
+
+    await $axios.post(ntfyUrl, ctx.data?.message || "Hello from scrunner", {
+      headers,
+    });
   }
 
-  if (ctx.data?.attach) {
-    log.info("ntfy: setting attach %s", ctx.data.attach);
-    headers.Attach = ctx.data.attach;
+  /** @type {Record<string, unknown>} */
+  const sent = { sent: "true" };
+  if (fingerprintKey && fp) {
+    const stored = await $fingerprint.remember(fingerprintKey, fp.hash);
+    sent.fingerprint = stored.hash;
+    sent.fingerprintAt = stored.at;
   }
-
-  const truncatedMessage = ctx.data?.message?.substring(0, 100);
-  log.info("ntfy sending message to %s", ntfyUrl);
-  log.info("ntfy messsage: %s", truncatedMessage);
-
-  await $axios.post(ntfyUrl, ctx.data?.message || "Hello from scrunner", {
-    headers,
-  });
-  return { sent: "true" };
+  return sent;
 }
 
 ntfy.meta = {
@@ -73,6 +137,21 @@ ntfy.meta = {
       default: "https://ntfy.sh/scrunner",
       description: "ntfy topic URL",
     },
+    fingerprint: {
+      type: "string",
+      required: false,
+      description: "true or a KV key; skip send when the payload fingerprint is unchanged",
+    },
+    fingerprintJsonata: {
+      type: "string",
+      required: false,
+      description: "JSONata against ctx; default hashes title, message, attach, filename, contentType",
+    },
+    fingerprintMaxAge: {
+      type: "string",
+      required: false,
+      description: "Optional age limit (e.g. 24h, 7d, or milliseconds)",
+    },
   },
   input: {
     title: { type: "string", required: false },
@@ -87,7 +166,7 @@ ntfy.meta = {
   },
   example: {
     data: { title: "Hello", message: "Hello from scrunner" },
-    config: { url: "https://ntfy.sh/scrunner" },
+    config: { url: "https://ntfy.sh/scrunner", fingerprint: true },
   },
 };
 
diff --git a/packages/server/src/api/kv.js b/packages/server/src/api/kv.js
new file mode 100644
index 0000000..3d7fe73
--- /dev/null
+++ b/packages/server/src/api/kv.js
@@ -0,0 +1,22 @@
+import { kvNamespaces, kvQuery } from "../../kv-store.js";
+
+/**
+ * @param {import("fastify").FastifyInstance} fastify
+ */
+export default async function kvPlugin(fastify) {
+  fastify.get("/kv/namespaces", async () => {
+    return { namespaces: await kvNamespaces() };
+  });
+
+  fastify.get("/kv", async (req) => {
+    const q = /** @type {Record<string, string | undefined>} */ (req.query ?? {});
+    const limit = q.limit != null ? Number(q.limit) : undefined;
+    const offset = q.offset != null ? Number(q.offset) : undefined;
+    return kvQuery({
+      namespace: q.namespace || undefined,
+      q: q.q || undefined,
+      limit: Number.isFinite(limit) ? limit : undefined,
+      offset: Number.isFinite(offset) ? offset : undefined,
+    });
+  });
+}
diff --git a/packages/server/test/fingerprint-smoke.js b/packages/server/test/fingerprint-smoke.js
new file mode 100644
index 0000000..3331cd3
--- /dev/null
+++ b/packages/server/test/fingerprint-smoke.js
@@ -0,0 +1,105 @@
+import { migrate, db } from "../db.js";
+import { createKvApi, kvDelete, kvSet } from "../kv-store.js";
+import {
+  createFingerprintApi,
+  hashFingerprint,
+} from "../script-fingerprint.js";
+import { runScriptSource } from "../script-sandbox.js";
+import { log } from "../logger.js";
+
+await migrate();
+
+const ns = "test/fingerprint-smoke";
+const api = createKvApi(ns);
+const fp = createFingerprintApi(api);
+
+for (const key of ["a", "b", "cas", "age", "legacy", "script-key"]) {
+  await kvDelete(ns, key);
+}
+
+const h1 = hashFingerprint({ b: 1, a: 2 });
+const h2 = hashFingerprint({ a: 2, b: 1 });
+if (h1 !== h2) throw new Error("hash should ignore key order");
+
+const bufHash = hashFingerprint(Buffer.from("hello"));
+const sameLen = hashFingerprint(Buffer.from("world"));
+if (bufHash !== sameLen) {
+  throw new Error("buffers of equal length should hash as { $bytes: length }");
+}
+const otherLen = hashFingerprint(Buffer.from("hi"));
+if (bufHash === otherLen) throw new Error("different byte lengths should hash differently");
+
+const first = await fp.check("a", { item: "one" });
+if (!first.changed || first.previous !== null) {
+  throw new Error(`first check should be changed: ${JSON.stringify(first)}`);
+}
+
+const remembered = await fp.remember("a", first.hash);
+if (remembered.hash !== first.hash || typeof remembered.at !== "string") {
+  throw new Error(`remember failed: ${JSON.stringify(remembered)}`);
+}
+
+const second = await fp.check("a", { item: "one" });
+if (second.changed) throw new Error("second check should be unchanged");
+if (second.previous !== first.hash) throw new Error("previous hash mismatch");
+if (second.previousAt !== remembered.at) throw new Error("previousAt should be kept");
+
+const claimNew = await fp.claim("b", "hello");
+if (!claimNew.changed) throw new Error("first claim should be changed");
+const storedAt = claimNew.at;
+
+const claimSame = await fp.claim("b", "hello");
+if (claimSame.changed) throw new Error("unchanged claim should return changed: false");
+if (claimSame.at !== storedAt) throw new Error("unchanged claim should keep original at");
+
+const oldAt = new Date(Date.now() - 8 * 24 * 60 * 60 * 1000).toISOString();
+const oldHash = hashFingerprint("aged");
+await kvSet(ns, "age", { hash: oldHash, at: oldAt });
+
+const agedNoMax = await fp.check("age", "aged");
+if (agedNoMax.changed) {
+  throw new Error("omit maxAge: matching hash should skip even if old");
+}
+
+const agedExpired = await fp.claim("age", "aged", { maxAge: "7d" });
+if (!agedExpired.changed || !agedExpired.expired) {
+  throw new Error(`maxAge should expire old hash: ${JSON.stringify(agedExpired)}`);
+}
+if (agedExpired.at === oldAt) throw new Error("expired claim should write a new at");
+
+const fresh = await fp.check("age", "aged", { maxAge: "7d" });
+if (fresh.changed || fresh.expired) {
+  throw new Error(`freshly claimed hash should not expire: ${JSON.stringify(fresh)}`);
+}
+
+await kvSet(ns, "legacy", oldHash);
+const legacyNoMax = await fp.check("legacy", "aged");
+if (legacyNoMax.changed) {
+  throw new Error("legacy bare hash should still match without maxAge");
+}
+const legacyExpired = await fp.check("legacy", "aged", { maxAge: "1h" });
+if (!legacyExpired.changed || !legacyExpired.expired) {
+  throw new Error(`legacy hash with maxAge should expire: ${JSON.stringify(legacyExpired)}`);
+}
+
+const script = `
+export default async function (ctx) {
+  const result = await $fingerprint.claim("script-key", ctx.data.n);
+  return result;
+}
+`;
+
+const scriptOut = await runScriptSource(
+  "fingerprint-smoke.js",
+  script,
+  { data: { n: 1 } },
+  { log, workflowName: ns },
+);
+if (!scriptOut.changed) throw new Error("sandbox $fingerprint.claim should be new");
+
+for (const key of ["a", "b", "cas", "age", "legacy", "script-key"]) {
+  await kvDelete(ns, key);
+}
+
+console.log("fingerprint smoke test passed");
+await db.destroy();
diff --git a/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml b/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml
index 5799284..dba12c2 100644
--- a/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml
+++ b/packages/server/workflows/default/rss-selfhst-to-ntfy.yaml
@@ -5,6 +5,10 @@ scripts:
       url: "https://selfh.st/rss/"
       outputVar: item
       jsonata: items[0]
+  - script: fingerprint.js
+    config:
+      key: selfhst-latest
+      jsonata: "data.item.guid ? data.item.guid : data.item.link"
   - script: jsonata.js
     config:
       expression: |
diff --git a/packages/web/src/App.jsx b/packages/web/src/App.jsx
index 9ac2e5e..c0674b9 100644
--- a/packages/web/src/App.jsx
+++ b/packages/web/src/App.jsx
@@ -12,6 +12,7 @@ import { WorkflowsPage } from "./pages/WorkflowsPage.jsx";
 import { WorkflowEditPage, WorkflowNewPage } from "./pages/WorkflowEditPage.jsx";
 import { EventsPage } from "./pages/EventsPage.jsx";
 import { EventDetailPage } from "./pages/EventDetailPage.jsx";
+import { KvPage } from "./pages/KvPage.jsx";
 import { UsersPage } from "./pages/UsersPage.jsx";
 import { SecretsPage } from "./pages/SecretsPage.jsx";
 
@@ -57,6 +58,7 @@ export function App() {
         <Route path="/workflows/:owner/:file/edit" element={<WorkflowEditPage />} />
         <Route path="/events" element={<EventsPage />} />
         <Route path="/events/:id" element={<EventDetailPage />} />
+        <Route path="/kv" element={<KvPage />} />
         {user.role === "admin" ? (
           <>
             <Route path="/users" element={<UsersPage />} />
diff --git a/packages/web/src/api/hooks.js b/packages/web/src/api/hooks.js
index c662b66..18e8949 100644
--- a/packages/web/src/api/hooks.js
+++ b/packages/web/src/api/hooks.js
@@ -313,3 +313,25 @@ export function useDeleteSecret() {
     onSuccess: () => qc.invalidateQueries({ queryKey: ["secrets"] }),
   });
 }
+
+export function useKvNamespaces() {
+  return useQuery({
+    queryKey: ["kv", "namespaces"],
+    queryFn: async () => (await api.get("/kv/namespaces")).data.namespaces,
+  });
+}
+
+export function useKv(filters = {}) {
+  const { namespace, q, limit, offset } = filters;
+  return useQuery({
+    queryKey: ["kv", { namespace, q, limit, offset }],
+    queryFn: async () => {
+      const params = {};
+      if (namespace) params.namespace = namespace;
+      if (q) params.q = q;
+      if (limit != null) params.limit = limit;
+      if (offset != null) params.offset = offset;
+      return (await api.get("/kv", { params })).data;
+    },
+  });
+}
diff --git a/packages/web/src/components/Layout.jsx b/packages/web/src/components/Layout.jsx
index 1d0564d..dc82807 100644
--- a/packages/web/src/components/Layout.jsx
+++ b/packages/web/src/components/Layout.jsx
@@ -2,6 +2,7 @@ import { NavLink, useNavigate } from "react-router-dom";
 import {
   LuActivity,
   LuCode,
+  LuDatabase,
   LuGitBranch,
   LuHouse,
   LuKey,
@@ -19,6 +20,7 @@ const links = [
   { to: "/scripts", label: "Scripts", icon: LuCode },
   { to: "/workflows", label: "Workflows", icon: LuGitBranch },
   { to: "/events", label: "Events", icon: LuActivity },
+  { to: "/kv", label: "KV", icon: LuDatabase },
 ];
 
 export function Layout({ user, children }) {
diff --git a/packages/web/src/pages/EventDetailPage.jsx b/packages/web/src/pages/EventDetailPage.jsx
index 1052f68..93de923 100644
--- a/packages/web/src/pages/EventDetailPage.jsx
+++ b/packages/web/src/pages/EventDetailPage.jsx
@@ -98,7 +98,7 @@ export function EventDetailPage() {
                 <th>Script</th>
                 <th>Status</th>
                 <th>Duration</th>
-                <th>Error</th>
+                <th>Detail</th>
                 <th></th>
               </tr>
             </thead>
@@ -119,7 +119,13 @@ export function EventDetailPage() {
                     <StatusBadge status={s.status} />
                   </td>
                   <td>{s.duration_ms != null ? `${s.duration_ms}ms` : "—"}</td>
-                  <td className="text-error text-xs">{s.error || ""}</td>
+                  <td
+                    className={
+                      s.status === "skipped" ? "opacity-60 text-xs" : "text-error text-xs"
+                    }
+                  >
+                    {s.error || ""}
+                  </td>
                   <td className="text-right">
                     <button
                       type="button"
diff --git a/packages/web/src/pages/KvPage.jsx b/packages/web/src/pages/KvPage.jsx
new file mode 100644
index 0000000..eae3275
--- /dev/null
+++ b/packages/web/src/pages/KvPage.jsx
@@ -0,0 +1,143 @@
+import { useState } from "react";
+import { useSearchParams } from "react-router-dom";
+import { useKv, useKvNamespaces } from "../api/hooks.js";
+import { formatTime } from "../lib/format.jsx";
+
+const PAGE_SIZE = 50;
+
+function previewValue(value) {
+  const json = JSON.stringify(value);
+  if (json == null) return "—";
+  if (json.length <= 120) return json;
+  return `${json.slice(0, 120)}…`;
+}
+
+export function KvPage() {
+  const [params, setParams] = useSearchParams();
+  const namespace = params.get("namespace") || "";
+  const q = params.get("q") || "";
+  const offset = Math.max(Number(params.get("offset")) || 0, 0);
+  const [expanded, setExpanded] = useState(null);
+
+  const { data: namespaces = [] } = useKvNamespaces();
+  const { data, isLoading } = useKv({
+    namespace: namespace || undefined,
+    q: q || undefined,
+    limit: PAGE_SIZE,
+    offset,
+  });
+
+  const items = data?.items ?? [];
+  const total = data?.total ?? 0;
+  const limit = data?.limit ?? PAGE_SIZE;
+
+  function update(key, value, resetOffset = true) {
+    const next = new URLSearchParams(params);
+    if (value) next.set(key, value);
+    else next.delete(key);
+    if (resetOffset && key !== "offset") next.delete("offset");
+    setParams(next);
+    setExpanded(null);
+  }
+
+  function rowId(item) {
+    return `${item.namespace}\0${item.key}`;
+  }
+
+  return (
+    <div className="space-y-4">
+      <h1 className="text-xl font-semibold">KV</h1>
+      <div className="flex flex-col sm:flex-row gap-2">
+        <select
+          className="select select-sm w-full sm:max-w-xs"
+          value={namespace}
+          onChange={(e) => update("namespace", e.target.value)}
+        >
+          <option value="">all namespaces</option>
+          {namespaces.map((ns) => (
+            <option key={ns} value={ns}>
+              {ns}
+            </option>
+          ))}
+        </select>
+        <input
+          className="input input-sm w-full sm:max-w-sm"
+          placeholder="search key or value"
+          value={q}
+          onChange={(e) => update("q", e.target.value)}
+        />
+      </div>
+      {isLoading ? (
+        <span className="loading loading-spinner" />
+      ) : items.length === 0 ? (
+        <p className="text-sm opacity-60">No KV entries.</p>
+      ) : (
+        <>
+          <div className="overflow-x-auto">
+            <table className="table table-sm">
+              <thead>
+                <tr>
+                  <th>Namespace</th>
+                  <th>Key</th>
+                  <th>Value</th>
+                  <th>Updated</th>
+                  <th>Expires</th>
+                </tr>
+              </thead>
+              <tbody>
+                {items.map((item) => {
+                  const id = rowId(item);
+                  const open = expanded === id;
+                  return (
+                    <tr
+                      key={id}
+                      className="hover cursor-pointer"
+                      onClick={() => setExpanded(open ? null : id)}
+                    >
+                      <td className="font-mono text-xs align-top">{item.namespace}</td>
+                      <td className="font-mono text-xs align-top">{item.key}</td>
+                      <td className="align-top">
+                        {open ? (
+                          <pre className="text-xs whitespace-pre-wrap break-all max-w-xl">
+                            {JSON.stringify(item.value, null, 2)}
+                          </pre>
+                        ) : (
+                          <span className="font-mono text-xs">{previewValue(item.value)}</span>
+                        )}
+                      </td>
+                      <td className="whitespace-nowrap align-top">{formatTime(item.updatedAt)}</td>
+                      <td className="whitespace-nowrap align-top">
+                        {item.expiresAt ? formatTime(item.expiresAt) : "—"}
+                      </td>
+                    </tr>
+                  );
+                })}
+              </tbody>
+            </table>
+          </div>
+          <div className="flex items-center gap-2 text-sm">
+            <button
+              type="button"
+              className="btn btn-sm"
+              disabled={offset <= 0}
+              onClick={() => update("offset", String(Math.max(offset - limit, 0)), false)}
+            >
+              Prev
+            </button>
+            <button
+              type="button"
+              className="btn btn-sm"
+              disabled={offset + items.length >= total}
+              onClick={() => update("offset", String(offset + limit), false)}
+            >
+              Next
+            </button>
+            <span className="opacity-60">
+              {total === 0 ? "0" : `${offset + 1}–${offset + items.length}`} of {total}
+            </span>
+          </div>
+        </>
+      )}
+    </div>
+  );
+}