diff --git a/ui/src/pages/Alerts/RuleEditor/ConditionStep.tsx b/ui/src/pages/Alerts/RuleEditor/ConditionStep.tsx
index a22fe75a..a3625e10 100644
--- a/ui/src/pages/Alerts/RuleEditor/ConditionStep.tsx
+++ b/ui/src/pages/Alerts/RuleEditor/ConditionStep.tsx
@@ -1,5 +1,49 @@
+import { FormField, Select } from '@cameleer/design-system';
 import type { FormState } from './form-state';
+import { RouteMetricForm } from './condition-forms/RouteMetricForm';
+import { ExchangeMatchForm } from './condition-forms/ExchangeMatchForm';
+import { AgentStateForm } from './condition-forms/AgentStateForm';
+import { DeploymentStateForm } from './condition-forms/DeploymentStateForm';
+import { LogPatternForm } from './condition-forms/LogPatternForm';
+import { JvmMetricForm } from './condition-forms/JvmMetricForm';
 
-export function ConditionStep({ form: _form, setForm: _setForm }: { form: FormState; setForm: (f: FormState) => void }) {
-  return <div>Condition step &mdash; TODO Task 21</div>;
+const KIND_OPTIONS = [
+  { value: 'ROUTE_METRIC', label: 'Route metric (error rate, latency, throughput)' },
+  { value: 'EXCHANGE_MATCH', label: 'Exchange match (specific failures)' },
+  { value: 'AGENT_STATE', label: 'Agent state (DEAD / STALE)' },
+  { value: 'DEPLOYMENT_STATE', label: 'Deployment state (FAILED / DEGRADED)' },
+  { value: 'LOG_PATTERN', label: 'Log pattern (count of matching logs)' },
+  { value: 'JVM_METRIC', label: 'JVM metric (heap, GC, inflight)' },
+];
+
+export function ConditionStep({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const onKindChange = (v: string) => {
+    const kind = v as FormState['conditionKind'];
+    // Reset the condition payload so stale fields from a previous kind don't leak
+    // into the save request. Preserve scope — it's managed on the scope step.
+    const prev = form.condition as Record<string, unknown>;
+    setForm({
+      ...form,
+      conditionKind: kind,
+      condition: { kind, scope: prev.scope } as FormState['condition'],
+    });
+  };
+
+  return (
+    <div style={{ display: 'grid', gap: 16, maxWidth: 720 }}>
+      <FormField label="Condition kind">
+        <Select
+          value={form.conditionKind}
+          onChange={(e) => onKindChange(e.target.value)}
+          options={KIND_OPTIONS}
+        />
+      </FormField>
+      {form.conditionKind === 'ROUTE_METRIC' && <RouteMetricForm form={form} setForm={setForm} />}
+      {form.conditionKind === 'EXCHANGE_MATCH' && <ExchangeMatchForm form={form} setForm={setForm} />}
+      {form.conditionKind === 'AGENT_STATE' && <AgentStateForm form={form} setForm={setForm} />}
+      {form.conditionKind === 'DEPLOYMENT_STATE' && <DeploymentStateForm form={form} setForm={setForm} />}
+      {form.conditionKind === 'LOG_PATTERN' && <LogPatternForm form={form} setForm={setForm} />}
+      {form.conditionKind === 'JVM_METRIC' && <JvmMetricForm form={form} setForm={setForm} />}
+    </div>
+  );
 }
diff --git a/ui/src/pages/Alerts/RuleEditor/condition-forms/AgentStateForm.tsx b/ui/src/pages/Alerts/RuleEditor/condition-forms/AgentStateForm.tsx
new file mode 100644
index 00000000..e50026cc
--- /dev/null
+++ b/ui/src/pages/Alerts/RuleEditor/condition-forms/AgentStateForm.tsx
@@ -0,0 +1,30 @@
+import { FormField, Input, Select } from '@cameleer/design-system';
+import type { FormState } from '../form-state';
+
+export function AgentStateForm({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const c = form.condition as Record<string, unknown>;
+  const patch = (p: Record<string, unknown>) =>
+    setForm({ ...form, condition: { ...(form.condition as Record<string, unknown>), ...p } as FormState['condition'] });
+
+  return (
+    <>
+      <FormField label="Agent state">
+        <Select
+          value={(c.state as string) ?? 'DEAD'}
+          onChange={(e) => patch({ state: e.target.value })}
+          options={[
+            { value: 'DEAD', label: 'DEAD' },
+            { value: 'STALE', label: 'STALE' },
+          ]}
+        />
+      </FormField>
+      <FormField label="For duration (seconds)">
+        <Input
+          type="number"
+          value={(c.forSeconds as number | undefined) ?? 60}
+          onChange={(e) => patch({ forSeconds: Number(e.target.value) })}
+        />
+      </FormField>
+    </>
+  );
+}
diff --git a/ui/src/pages/Alerts/RuleEditor/condition-forms/DeploymentStateForm.tsx b/ui/src/pages/Alerts/RuleEditor/condition-forms/DeploymentStateForm.tsx
new file mode 100644
index 00000000..5497add4
--- /dev/null
+++ b/ui/src/pages/Alerts/RuleEditor/condition-forms/DeploymentStateForm.tsx
@@ -0,0 +1,26 @@
+import { FormField } from '@cameleer/design-system';
+import type { FormState } from '../form-state';
+
+const OPTIONS = ['FAILED', 'DEGRADED'] as const;
+
+export function DeploymentStateForm({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const c = form.condition as Record<string, unknown>;
+  const states: string[] = (c.states as string[] | undefined) ?? [];
+  const toggle = (s: string) => {
+    const next = states.includes(s) ? states.filter((x) => x !== s) : [...states, s];
+    setForm({ ...form, condition: { ...(form.condition as Record<string, unknown>), states: next } as FormState['condition'] });
+  };
+
+  return (
+    <FormField label="Fire when deployment is in states">
+      <div style={{ display: 'flex', gap: 12 }}>
+        {OPTIONS.map((s) => (
+          <label key={s} style={{ display: 'flex', alignItems: 'center', gap: 4 }}>
+            <input type="checkbox" checked={states.includes(s)} onChange={() => toggle(s)} />
+            {s}
+          </label>
+        ))}
+      </div>
+    </FormField>
+  );
+}
diff --git a/ui/src/pages/Alerts/RuleEditor/condition-forms/ExchangeMatchForm.tsx b/ui/src/pages/Alerts/RuleEditor/condition-forms/ExchangeMatchForm.tsx
new file mode 100644
index 00000000..e2e360f4
--- /dev/null
+++ b/ui/src/pages/Alerts/RuleEditor/condition-forms/ExchangeMatchForm.tsx
@@ -0,0 +1,67 @@
+import { FormField, Input, Select } from '@cameleer/design-system';
+import type { FormState } from '../form-state';
+
+const FIRE_MODES = [
+  { value: 'PER_EXCHANGE', label: 'One alert per matching exchange' },
+  { value: 'COUNT_IN_WINDOW', label: 'Threshold: N matches in window' },
+];
+
+const STATUSES = [
+  { value: '', label: '(any)' },
+  { value: 'COMPLETED', label: 'COMPLETED' },
+  { value: 'FAILED', label: 'FAILED' },
+  { value: 'RUNNING', label: 'RUNNING' },
+];
+
+export function ExchangeMatchForm({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const c = form.condition as Record<string, unknown>;
+  const filter = (c.filter as Record<string, unknown> | undefined) ?? {};
+  const patch = (p: Record<string, unknown>) =>
+    setForm({ ...form, condition: { ...(form.condition as Record<string, unknown>), ...p } as FormState['condition'] });
+
+  return (
+    <>
+      <FormField label="Fire mode">
+        <Select
+          value={(c.fireMode as string) ?? 'PER_EXCHANGE'}
+          onChange={(e) => patch({ fireMode: e.target.value })}
+          options={FIRE_MODES}
+        />
+      </FormField>
+      <FormField label="Status filter">
+        <Select
+          value={(filter.status as string) ?? ''}
+          onChange={(e) => patch({ filter: { ...filter, status: e.target.value || undefined } })}
+          options={STATUSES}
+        />
+      </FormField>
+      {c.fireMode === 'PER_EXCHANGE' && (
+        <FormField label="Linger seconds (default 300)">
+          <Input
+            type="number"
+            value={(c.perExchangeLingerSeconds as number | undefined) ?? 300}
+            onChange={(e) => patch({ perExchangeLingerSeconds: Number(e.target.value) })}
+          />
+        </FormField>
+      )}
+      {c.fireMode === 'COUNT_IN_WINDOW' && (
+        <>
+          <FormField label="Threshold (matches)">
+            <Input
+              type="number"
+              value={(c.threshold as number | undefined) ?? ''}
+              onChange={(e) => patch({ threshold: Number(e.target.value) })}
+            />
+          </FormField>
+          <FormField label="Window (seconds)">
+            <Input
+              type="number"
+              value={(c.windowSeconds as number | undefined) ?? 900}
+              onChange={(e) => patch({ windowSeconds: Number(e.target.value) })}
+            />
+          </FormField>
+        </>
+      )}
+    </>
+  );
+}
diff --git a/ui/src/pages/Alerts/RuleEditor/condition-forms/JvmMetricForm.tsx b/ui/src/pages/Alerts/RuleEditor/condition-forms/JvmMetricForm.tsx
new file mode 100644
index 00000000..59b7bcd9
--- /dev/null
+++ b/ui/src/pages/Alerts/RuleEditor/condition-forms/JvmMetricForm.tsx
@@ -0,0 +1,57 @@
+import { FormField, Input, Select } from '@cameleer/design-system';
+import type { FormState } from '../form-state';
+
+export function JvmMetricForm({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const c = form.condition as Record<string, unknown>;
+  const patch = (p: Record<string, unknown>) =>
+    setForm({ ...form, condition: { ...(form.condition as Record<string, unknown>), ...p } as FormState['condition'] });
+
+  return (
+    <>
+      <FormField label="Metric name">
+        <Input
+          value={(c.metric as string | undefined) ?? ''}
+          onChange={(e) => patch({ metric: e.target.value })}
+          placeholder="heap_used_percent"
+        />
+      </FormField>
+      <FormField label="Aggregation">
+        <Select
+          value={(c.aggregation as string) ?? 'MAX'}
+          onChange={(e) => patch({ aggregation: e.target.value })}
+          options={[
+            { value: 'MAX', label: 'MAX' },
+            { value: 'AVG', label: 'AVG' },
+            { value: 'MIN', label: 'MIN' },
+          ]}
+        />
+      </FormField>
+      <FormField label="Comparator">
+        <Select
+          value={(c.comparator as string) ?? 'GT'}
+          onChange={(e) => patch({ comparator: e.target.value })}
+          options={[
+            { value: 'GT', label: '>' },
+            { value: 'GTE', label: '\u2265' },
+            { value: 'LT', label: '<' },
+            { value: 'LTE', label: '\u2264' },
+          ]}
+        />
+      </FormField>
+      <FormField label="Threshold">
+        <Input
+          type="number"
+          value={(c.threshold as number | undefined) ?? ''}
+          onChange={(e) => patch({ threshold: Number(e.target.value) })}
+        />
+      </FormField>
+      <FormField label="Window (seconds)">
+        <Input
+          type="number"
+          value={(c.windowSeconds as number | undefined) ?? 300}
+          onChange={(e) => patch({ windowSeconds: Number(e.target.value) })}
+        />
+      </FormField>
+    </>
+  );
+}
diff --git a/ui/src/pages/Alerts/RuleEditor/condition-forms/LogPatternForm.tsx b/ui/src/pages/Alerts/RuleEditor/condition-forms/LogPatternForm.tsx
new file mode 100644
index 00000000..b34efba4
--- /dev/null
+++ b/ui/src/pages/Alerts/RuleEditor/condition-forms/LogPatternForm.tsx
@@ -0,0 +1,50 @@
+import { FormField, Input, Select } from '@cameleer/design-system';
+import type { FormState } from '../form-state';
+
+export function LogPatternForm({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const c = form.condition as Record<string, unknown>;
+  const patch = (p: Record<string, unknown>) =>
+    setForm({ ...form, condition: { ...(form.condition as Record<string, unknown>), ...p } as FormState['condition'] });
+
+  return (
+    <>
+      <FormField label="Level">
+        <Select
+          value={(c.level as string) ?? 'ERROR'}
+          onChange={(e) => patch({ level: e.target.value })}
+          options={[
+            { value: 'ERROR', label: 'ERROR' },
+            { value: 'WARN', label: 'WARN' },
+            { value: 'INFO', label: 'INFO' },
+          ]}
+        />
+      </FormField>
+      <FormField label="Logger (substring, optional)">
+        <Input
+          value={(c.logger as string | undefined) ?? ''}
+          onChange={(e) => patch({ logger: e.target.value || undefined })}
+        />
+      </FormField>
+      <FormField label="Pattern (regex)">
+        <Input
+          value={(c.pattern as string | undefined) ?? ''}
+          onChange={(e) => patch({ pattern: e.target.value })}
+        />
+      </FormField>
+      <FormField label="Threshold (matches)">
+        <Input
+          type="number"
+          value={(c.threshold as number | undefined) ?? ''}
+          onChange={(e) => patch({ threshold: Number(e.target.value) })}
+        />
+      </FormField>
+      <FormField label="Window (seconds)">
+        <Input
+          type="number"
+          value={(c.windowSeconds as number | undefined) ?? 900}
+          onChange={(e) => patch({ windowSeconds: Number(e.target.value) })}
+        />
+      </FormField>
+    </>
+  );
+}
diff --git a/ui/src/pages/Alerts/RuleEditor/condition-forms/RouteMetricForm.tsx b/ui/src/pages/Alerts/RuleEditor/condition-forms/RouteMetricForm.tsx
new file mode 100644
index 00000000..e8138110
--- /dev/null
+++ b/ui/src/pages/Alerts/RuleEditor/condition-forms/RouteMetricForm.tsx
@@ -0,0 +1,57 @@
+import { FormField, Input, Select } from '@cameleer/design-system';
+import type { FormState } from '../form-state';
+
+const METRICS = [
+  { value: 'ERROR_RATE', label: 'Error rate' },
+  { value: 'P95_LATENCY_MS', label: 'P95 latency (ms)' },
+  { value: 'P99_LATENCY_MS', label: 'P99 latency (ms)' },
+  { value: 'AVG_DURATION_MS', label: 'Avg duration (ms)' },
+  { value: 'THROUGHPUT', label: 'Throughput (msg/s)' },
+  { value: 'ERROR_COUNT', label: 'Error count' },
+];
+
+const COMPARATORS = [
+  { value: 'GT', label: '>' },
+  { value: 'GTE', label: '\u2265' },
+  { value: 'LT', label: '<' },
+  { value: 'LTE', label: '\u2264' },
+];
+
+export function RouteMetricForm({ form, setForm }: { form: FormState; setForm: (f: FormState) => void }) {
+  const c = form.condition as Record<string, unknown>;
+  const patch = (p: Record<string, unknown>) =>
+    setForm({ ...form, condition: { ...(form.condition as Record<string, unknown>), ...p } as FormState['condition'] });
+
+  return (
+    <>
+      <FormField label="Metric">
+        <Select
+          value={(c.metric as string) ?? ''}
+          onChange={(e) => patch({ metric: e.target.value })}
+          options={METRICS}
+        />
+      </FormField>
+      <FormField label="Comparator">
+        <Select
+          value={(c.comparator as string) ?? 'GT'}
+          onChange={(e) => patch({ comparator: e.target.value })}
+          options={COMPARATORS}
+        />
+      </FormField>
+      <FormField label="Threshold">
+        <Input
+          type="number"
+          value={(c.threshold as number | undefined) ?? ''}
+          onChange={(e) => patch({ threshold: Number(e.target.value) })}
+        />
+      </FormField>
+      <FormField label="Window (seconds)">
+        <Input
+          type="number"
+          value={(c.windowSeconds as number | undefined) ?? 300}
+          onChange={(e) => patch({ windowSeconds: Number(e.target.value) })}
+        />
+      </FormField>
+    </>
+  );
+}