diff --git a/cdk/src/constructs/jira-integration.ts b/cdk/src/constructs/jira-integration.ts
index 4c666e3a..1dac4c70 100644
--- a/cdk/src/constructs/jira-integration.ts
+++ b/cdk/src/constructs/jira-integration.ts
@@ -148,7 +148,7 @@ export class JiraIntegration extends Construct {
    */
   public readonly workspaceRegistryTable: dynamodb.Table;
 
-  /** Webhook dedup table — `{issueKey}#{webhookEvent}#{timestamp}` keys with 8h TTL. */
+  /** Webhook dedup table — issue timestamps or stable comment IDs, with an 8h TTL. */
   public readonly webhookDedupTable: dynamodb.Table;
 
   /** Jira webhook signing secret (placeholder — populated by `bgagent jira setup`). */
@@ -168,7 +168,8 @@ export class JiraIntegration extends Construct {
     this.workspaceRegistryTable = workspaceRegistry.table;
 
     // Dedup table: Jira webhook retries collapse to a single processor invoke
-    // within the 8h TTL window. Keyed on `{issueKey}#{webhookEvent}#{timestamp}`.
+    // within the 8h TTL window. Issue events use the event timestamp; comment
+    // events use the stable Jira comment ID.
     this.webhookDedupTable = new dynamodb.Table(this, 'WebhookDedupTable', {
       partitionKey: { name: 'dedup_key', type: dynamodb.AttributeType.STRING },
       billingMode: dynamodb.BillingMode.PAY_PER_REQUEST,
diff --git a/cdk/src/constructs/task-table-indexes.ts b/cdk/src/constructs/task-table-indexes.ts
new file mode 100644
index 00000000..d514db1a
--- /dev/null
+++ b/cdk/src/constructs/task-table-indexes.ts
@@ -0,0 +1,26 @@
+/**
+ *  MIT No Attribution
+ *
+ *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy of
+ *  the Software without restriction, including without limitation the rights to
+ *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ *  the Software, and to permit persons to whom the Software is furnished to do so.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+/**
+ * GSI name for resolving Jira-origin tasks by tenant and issue key.
+ *
+ * Kept dependency-free because both CDK constructs and bundled Lambda handlers
+ * use this deployment/runtime contract.
+ */
+export const JIRA_ISSUE_INDEX_NAME = 'JiraIssueIndex';
diff --git a/cdk/src/constructs/task-table.ts b/cdk/src/constructs/task-table.ts
index dfbf9e27..1e9c6599 100644
--- a/cdk/src/constructs/task-table.ts
+++ b/cdk/src/constructs/task-table.ts
@@ -20,6 +20,9 @@
 import { RemovalPolicy } from 'aws-cdk-lib';
 import * as dynamodb from 'aws-cdk-lib/aws-dynamodb';
 import { Construct } from 'constructs';
+import { JIRA_ISSUE_INDEX_NAME } from './task-table-indexes';
+
+export { JIRA_ISSUE_INDEX_NAME } from './task-table-indexes';
 
 /**
  * Properties for TaskTable construct.
@@ -47,13 +50,15 @@ export interface TaskTableProps {
 /**
  * DynamoDB table for persisting task state across the agent lifecycle.
  *
- * Schema: task_id (PK) with three GSIs for querying by user+status,
- * by status (queue processing), and by idempotency key (dedup).
+ * Schema: task_id (PK) with GSIs for querying by user+status, by status
+ * (queue processing), by idempotency key (dedup), and by Jira issue.
  *
  * GSIs:
  * - UserStatusIndex (PK: user_id, SK: status_created_at) — "my tasks" queries
  * - StatusIndex (PK: status, SK: created_at) — queue processing, monitoring
  * - IdempotencyIndex (PK: idempotency_key) — sparse index for dedup
+ * - JiraIssueIndex (PK: jira_issue_identity, SK: created_at) — sparse index
+ *   for resolving a Jira issue to its newest PR-producing task
  */
 export class TaskTable extends Construct {
   /**
@@ -74,6 +79,12 @@ export class TaskTable extends Construct {
    */
   public static readonly IDEMPOTENCY_INDEX = 'IdempotencyIndex';
 
+  /**
+   * GSI for resolving a tenant-scoped Jira issue to its newest ABCA task.
+   * PK: jira_issue_identity (`{cloudId}#{issueKey}`), SK: created_at.
+   */
+  public static readonly JIRA_ISSUE_INDEX = JIRA_ISSUE_INDEX_NAME;
+
   /**
    * The underlying DynamoDB table. Use this to grant access or read the table name.
    */
@@ -118,5 +129,16 @@ export class TaskTable extends Construct {
       partitionKey: { name: 'idempotency_key', type: dynamodb.AttributeType.STRING },
       projectionType: dynamodb.ProjectionType.KEYS_ONLY,
     });
+
+    // Sparse: only Jira-origin tasks with issue metadata carry the top-level
+    // jira_issue_identity attribute. Keep the projection limited to fields the
+    // comment-trigger resolver needs.
+    this.table.addGlobalSecondaryIndex({
+      indexName: TaskTable.JIRA_ISSUE_INDEX,
+      partitionKey: { name: 'jira_issue_identity', type: dynamodb.AttributeType.STRING },
+      sortKey: { name: 'created_at', type: dynamodb.AttributeType.STRING },
+      projectionType: dynamodb.ProjectionType.INCLUDE,
+      nonKeyAttributes: ['pr_url', 'pr_number', 'status', 'repo', 'user_id', 'channel_metadata'],
+    });
   }
 }
diff --git a/cdk/src/handlers/jira-webhook-processor.ts b/cdk/src/handlers/jira-webhook-processor.ts
index 3ab5ea95..5b50a7de 100644
--- a/cdk/src/handlers/jira-webhook-processor.ts
+++ b/cdk/src/handlers/jira-webhook-processor.ts
@@ -24,6 +24,10 @@ import { S3Client } from '@aws-sdk/client-s3';
 import { DynamoDBDocumentClient, GetCommand, ScanCommand } from '@aws-sdk/lib-dynamodb';
 import { ulid } from 'ulid';
 import type { ScreeningConfig } from './shared/attachment-screening';
+import {
+  buildIterationInstruction,
+  parseCommentTrigger,
+} from './shared/comment-trigger';
 import { createTaskCore } from './shared/create-task-core';
 import { extractDescriptionMarkdown } from './shared/jira-adf';
 import {
@@ -35,6 +39,11 @@ import {
 } from './shared/jira-attachments';
 import { reportIssueFailure } from './shared/jira-feedback';
 import { resolveJiraOauthToken } from './shared/jira-oauth-resolver';
+import {
+  prNumberFromTask,
+  resolveTaskByJiraIssue,
+  type JiraIssueTask,
+} from './shared/jira-task-by-issue';
 import { logger } from './shared/logger';
 import type { Attachment, PassedAttachmentRecord } from './shared/types';
 import { MAX_TASK_DESCRIPTION_LENGTH } from './shared/validation';
@@ -44,6 +53,7 @@ const ddb = DynamoDBDocumentClient.from(new DynamoDBClient({}));
 
 const PROJECT_MAPPING_TABLE = process.env.JIRA_PROJECT_MAPPING_TABLE_NAME!;
 const USER_MAPPING_TABLE = process.env.JIRA_USER_MAPPING_TABLE_NAME!;
+const TASK_TABLE = process.env.TASK_TABLE_NAME!;
 const WORKSPACE_REGISTRY_TABLE = process.env.JIRA_WORKSPACE_REGISTRY_TABLE_NAME;
 const DEFAULT_LABEL_FILTER = 'bgagent';
 
@@ -156,7 +166,7 @@ async function resolveSoleTenantCloudId(): Promise<string | undefined> {
  * Undocumented fields are tolerated.
  */
 interface JiraIssueEvent {
-  readonly webhookEvent: 'jira:issue_created' | 'jira:issue_updated' | string;
+  readonly webhookEvent: 'jira:issue_created' | 'jira:issue_updated' | 'comment_created' | string;
   readonly timestamp?: number;
   readonly cloudId?: string;
   readonly user?: {
@@ -189,6 +199,15 @@ interface JiraIssueEvent {
       readonly toString?: string | null;
     }>;
   };
+  readonly comment?: {
+    readonly id?: string;
+    readonly body?: unknown;
+    readonly author?: {
+      readonly accountId?: string;
+      readonly accountType?: string;
+      readonly displayName?: string;
+    };
+  };
 }
 
 interface ProcessorEvent {
@@ -236,11 +255,12 @@ export async function handler(event: ProcessorEvent): Promise<void> {
     return;
   }
 
-  if (
-    payload.webhookEvent !== 'jira:issue_created' &&
-    payload.webhookEvent !== 'jira:issue_updated'
-  ) {
-    logger.info('Jira processor skipping non-issue event', { webhookEvent: payload.webhookEvent });
+  const isIssueEvent =
+    payload.webhookEvent === 'jira:issue_created'
+    || payload.webhookEvent === 'jira:issue_updated';
+  const isCommentEvent = payload.webhookEvent === 'comment_created';
+  if (!isIssueEvent && !isCommentEvent) {
+    logger.info('Jira processor skipping unsupported event', { webhookEvent: payload.webhookEvent });
     return;
   }
 
@@ -274,6 +294,18 @@ export async function handler(event: ProcessorEvent): Promise<void> {
   } else {
     cloudId = payload.cloudId ?? (await resolveSoleTenantCloudId());
   }
+
+  if (isCommentEvent) {
+    if (!cloudId) {
+      logger.warn('Jira comment webhook missing cloudId and no sole active tenant', {
+        issue_key: issue.key,
+      });
+      return;
+    }
+    await handleCommentTrigger(payload, issue, cloudId);
+    return;
+  }
+
   const projectKey = issue.fields?.project?.key;
   if (!projectKey) {
     logger.info('Jira issue has no project.key — skipping (cannot route to a repo)', {
@@ -544,6 +576,211 @@ export async function handler(event: ProcessorEvent): Promise<void> {
   });
 }
 
+/**
+ * Handle `comment_created` independently of the label-trigger path.
+ *
+ * The prior task is the routing source of truth: comments do not require the
+ * trigger label to still be present or the Jira project mapping to remain
+ * active. This preserves reviewer follow-ups after the original run.
+ */
+async function handleCommentTrigger(
+  payload: JiraIssueEvent,
+  issue: NonNullable<JiraIssueEvent['issue']>,
+  cloudId: string,
+): Promise<void> {
+  const comment = payload.comment;
+  if (!comment?.id) {
+    logger.warn('Jira comment payload missing comment.id', { issue_key: issue.key });
+    return;
+  }
+
+  // Native app users are never human reviewers. ABCA's own 3LO comments are
+  // attributed to the authorizing Atlassian user, so parseCommentTrigger also
+  // rejects ABCA's stable rendered prefixes to prevent self-trigger loops.
+  if (comment.author?.accountType?.toLowerCase() === 'app') {
+    logger.info('Ignoring Jira app-authored comment', {
+      issue_key: issue.key,
+      comment_id: comment.id,
+    });
+    return;
+  }
+
+  const commentBody = extractDescriptionMarkdown(comment.body);
+  const trigger = parseCommentTrigger(commentBody);
+  if (!trigger.triggered) {
+    logger.info('Jira comment has no @bgagent trigger', {
+      issue_key: issue.key,
+      comment_id: comment.id,
+    });
+    return;
+  }
+
+  const priorTask = await resolveTaskByJiraIssue(
+    ddb,
+    TASK_TABLE,
+    cloudId,
+    issue.key,
+  );
+  const prNumber = priorTask ? prNumberFromTask(priorTask) : null;
+  if (!priorTask || prNumber === null) {
+    await safeReportIssueFailure(
+      issue.key,
+      cloudId,
+      "❌ I couldn't find an ABCA pull request for this Jira issue. Run the issue with the configured ABCA trigger label first, then retry this comment.",
+    );
+    return;
+  }
+  if (!priorTask.repo) {
+    await safeReportIssueFailure(
+      issue.key,
+      cloudId,
+      "❌ I found the earlier ABCA task, but it has no repository recorded, so I can't update its pull request.",
+    );
+    return;
+  }
+
+  const linkedCommentAuthor = comment.author?.accountId
+    ? await lookupPlatformUser(cloudId, comment.author.accountId)
+    : null;
+  const platformUserId = linkedCommentAuthor ?? priorTask.user_id;
+  if (!platformUserId) {
+    await safeReportIssueFailure(
+      issue.key,
+      cloudId,
+      '❌ I found the pull request, but neither the comment author nor the original task has a linked ABCA user.',
+    );
+    return;
+  }
+
+  if (!WORKSPACE_REGISTRY_TABLE) {
+    logger.warn('Cannot run Jira comment iteration: workspace registry is not configured', {
+      issue_key: issue.key,
+      comment_id: comment.id,
+    });
+    return;
+  }
+  const resolved = await resolveJiraOauthToken(cloudId, WORKSPACE_REGISTRY_TABLE);
+  if (!resolved) {
+    logger.warn('Cannot run Jira comment iteration: tenant OAuth is unavailable', {
+      jira_cloud_id: cloudId,
+      issue_key: issue.key,
+      comment_id: comment.id,
+    });
+    return;
+  }
+
+  const channelMetadata = buildIterationChannelMetadata(
+    priorTask,
+    issue,
+    cloudId,
+    comment.id,
+    resolved.oauthSecretArn,
+    resolved.siteUrl,
+  );
+  const idempotencyKey = buildCommentIdempotencyKey(cloudId, issue.key, comment.id);
+  const requestId = crypto.randomUUID();
+  const result = await createTaskCore(
+    {
+      repo: priorTask.repo,
+      workflow_ref: 'coding/pr-iteration-v1',
+      pr_number: prNumber,
+      task_description: buildIterationInstruction(trigger),
+    },
+    {
+      userId: platformUserId,
+      channelSource: 'jira',
+      channelMetadata,
+      idempotencyKey,
+    },
+    requestId,
+  );
+
+  if (result.statusCode === 200) {
+    logger.info('Jira comment iteration was an idempotent replay', {
+      issue_key: issue.key,
+      comment_id: comment.id,
+      prior_task_id: priorTask.task_id,
+    });
+    return;
+  }
+
+  if (result.statusCode !== 201) {
+    logger.warn('Jira comment iteration task creation returned non-201', {
+      status: result.statusCode,
+      body: result.body,
+      issue_key: issue.key,
+      comment_id: comment.id,
+    });
+    await safeReportIssueFailure(
+      issue.key,
+      cloudId,
+      buildCreateTaskFailureMessage(
+        result.statusCode,
+        result.body,
+        'Please add a new `@bgagent` comment in a few minutes.',
+      ),
+    );
+    return;
+  }
+
+  await safeReportIssueFailure(
+    issue.key,
+    cloudId,
+    `👀 ABCA accepted this follow-up and is updating PR #${prNumber}.`,
+  );
+  logger.info('Jira comment-triggered PR iteration task created', {
+    issue_key: issue.key,
+    comment_id: comment.id,
+    prior_task_id: priorTask.task_id,
+    repo: priorTask.repo,
+    pr_number: prNumber,
+    attributed_to_linked_comment_author: Boolean(linkedCommentAuthor),
+    request_id: requestId,
+  });
+}
+
+function buildIterationChannelMetadata(
+  priorTask: JiraIssueTask,
+  issue: NonNullable<JiraIssueEvent['issue']>,
+  cloudId: string,
+  commentId: string,
+  oauthSecretArn: string,
+  siteUrl: string,
+): Record<string, string> {
+  const previous = priorTask.channel_metadata ?? {};
+  const metadata: Record<string, string> = {
+    jira_cloud_id: cloudId,
+    jira_issue_id: issue.id,
+    jira_issue_key: issue.key,
+    jira_oauth_secret_arn: oauthSecretArn,
+    jira_site_url: siteUrl,
+    jira_trigger_comment_id: commentId,
+    jira_prior_task_id: priorTask.task_id,
+  };
+
+  const projectKey = issue.fields?.project?.key ?? previous.jira_project_key;
+  if (projectKey) metadata.jira_project_key = projectKey;
+  if (previous.jira_status_on_start) {
+    metadata.jira_status_on_start = previous.jira_status_on_start;
+  }
+  if (previous.jira_status_on_pr) {
+    metadata.jira_status_on_pr = previous.jira_status_on_pr;
+  }
+  return metadata;
+}
+
+function buildCommentIdempotencyKey(
+  cloudId: string,
+  issueKey: string,
+  commentId: string,
+): string {
+  const digest = crypto
+    .createHash('sha256')
+    .update(`${cloudId}\0${issueKey}\0${commentId}`)
+    .digest('hex');
+  return `jira-iterate-${digest}`;
+}
+
 /**
  * Decide whether a Jira issue event should trigger a task.
  *
@@ -598,7 +835,11 @@ function tokenizeLabelString(value: string | null | undefined): string[] {
  * Translate a `createTaskCore` non-201 response into a user-facing Jira
  * comment. Mirrors the Linear-side helper.
  */
-function buildCreateTaskFailureMessage(statusCode: number, rawBody: string): string {
+function buildCreateTaskFailureMessage(
+  statusCode: number,
+  rawBody: string,
+  retryHint = 'Please re-apply the trigger label in a few minutes.',
+): string {
   let detail = '';
   try {
     if (rawBody) {
@@ -616,7 +857,7 @@ function buildCreateTaskFailureMessage(statusCode: number, rawBody: string): str
     return `❌ ABCA couldn't accept this task: ${detail}`;
   }
   if (statusCode === 503) {
-    return `❌ ABCA is temporarily unavailable (status ${statusCode}). Please re-apply the trigger label in a few minutes.`;
+    return `❌ ABCA is temporarily unavailable (status ${statusCode}). ${retryHint}`;
   }
   if (detail) {
     return `❌ ABCA couldn't create this task (status ${statusCode}): ${detail}`;
diff --git a/cdk/src/handlers/jira-webhook.ts b/cdk/src/handlers/jira-webhook.ts
index 3efe2cf8..80ae5cc7 100644
--- a/cdk/src/handlers/jira-webhook.ts
+++ b/cdk/src/handlers/jira-webhook.ts
@@ -59,6 +59,9 @@ interface JiraWebhookEnvelope {
     readonly key?: string;
     readonly fields?: { readonly project?: { readonly id?: string; readonly key?: string } };
   };
+  readonly comment?: {
+    readonly id?: string;
+  };
   /** `cloudId` is delivered as a top-level field on Atlassian Cloud webhooks. */
   readonly matchedWebhookIds?: number[];
   readonly user?: { readonly accountId?: string };
@@ -79,7 +82,8 @@ interface JiraEnvelopeWithCloud extends JiraWebhookEnvelope {
  * POST /v1/jira/webhook — Jira Cloud webhook receiver.
  *
  * Verifies the `X-Hub-Signature` HMAC over the raw body, dedups on
- * `(issueKey, webhookEvent, timestamp)` with an 8h TTL, and async-invokes
+ * issue events on `(issueKey, webhookEvent, timestamp)` and comment events on
+ * `(issueKey, comment_created, commentId)` with an 8h TTL, then async-invokes
  * the processor Lambda so we can ack quickly. Atlassian sends the
  * algorithm prefix (`sha256=…`) — `verifyJiraSignature` strips it before
  * comparison.
@@ -184,9 +188,12 @@ export async function handler(event: APIGatewayProxyEvent): Promise<APIGatewayPr
     }
 
     const webhookEvent = payload.webhookEvent;
-    if (webhookEvent !== 'jira:issue_created' && webhookEvent !== 'jira:issue_updated') {
-      // Silent 200 so Atlassian doesn't retry — every non-issue event is acked.
-      logger.info('Ignoring non-Issue Jira webhook', { webhookEvent });
+    const isIssueEvent =
+      webhookEvent === 'jira:issue_created' || webhookEvent === 'jira:issue_updated';
+    const isCommentEvent = webhookEvent === 'comment_created';
+    if (!isIssueEvent && !isCommentEvent) {
+      // Silent 200 so Atlassian doesn't retry unsupported event types.
+      logger.info('Ignoring unsupported Jira webhook', { webhookEvent });
       return jsonResponse(200, { ok: true });
     }
 
@@ -194,18 +201,25 @@ export async function handler(event: APIGatewayProxyEvent): Promise<APIGatewayPr
     const issueId = issue?.id;
     const issueKey = issue?.key;
     if (!issueId || !issueKey) {
-      logger.warn('Jira Issue webhook missing issue.id or issue.key', { webhookEvent });
+      logger.warn('Jira webhook missing issue.id or issue.key', { webhookEvent });
       return jsonResponse(400, { error: 'Missing issue identifier' });
     }
+    const commentId = payload.comment?.id;
+    if (isCommentEvent && !commentId) {
+      logger.warn('Jira comment webhook missing comment.id', { issue_key: issueKey });
+      return jsonResponse(400, { error: 'Missing comment identifier' });
+    }
 
     // Dedup via conditional PutItem.
     //
-    // Atlassian doesn't expose a per-delivery message ID we can rely on. The
-    // payload's top-level `timestamp` (UNIX ms) is set when the event was
-    // queued and remains stable across retries of the same delivery.
-    // Composing `${issueKey}#${webhookEvent}#${timestamp}` collapses retries
-    // (same timestamp) without merging distinct events.
-    const dedupKey = `${issueKey}#${webhookEvent}#${payload.timestamp ?? 'unknown'}`;
+    // Comment ids are stable and unique, so they are the strongest dedup key
+    // for comment_created. Issue events have no entity id beyond the issue and
+    // continue using the delivery timestamp so separate label additions do not
+    // collapse into one event.
+    const dedupDiscriminator = isCommentEvent
+      ? commentId!
+      : payload.timestamp ?? 'unknown';
+    const dedupKey = `${issueKey}#${webhookEvent}#${dedupDiscriminator}`;
     const nowSeconds = Math.floor(Date.now() / 1000);
     try {
       await ddb.send(new PutCommand({
diff --git a/cdk/src/handlers/shared/comment-trigger.ts b/cdk/src/handlers/shared/comment-trigger.ts
new file mode 100644
index 00000000..4182bed1
--- /dev/null
+++ b/cdk/src/handlers/shared/comment-trigger.ts
@@ -0,0 +1,79 @@
+/**
+ *  MIT No Attribution
+ *
+ *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy of
+ *  the Software without restriction, including without limitation the rights to
+ *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ *  the Software, and to permit persons to whom the Software is furnished to do so.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+/** The explicit mention that turns a channel comment into an instruction. */
+export const COMMENT_TRIGGER_MENTION = '@bgagent';
+
+export interface CommentTrigger {
+  readonly triggered: boolean;
+  readonly instruction: string;
+}
+
+/**
+ * Parse a channel-neutral `@bgagent` comment trigger.
+ *
+ * The token match is case-insensitive and rejects handle/email prefixes such
+ * as `@bgagentbot` and `foo@bgagent.io`. All mention occurrences are removed
+ * from the instruction. A bare mention remains a valid trigger; callers can
+ * supply workflow-specific fallback text.
+ */
+export function parseCommentTrigger(body: string | undefined | null): CommentTrigger {
+  if (!body || isKnownAbcaComment(body)) {
+    return { triggered: false, instruction: '' };
+  }
+
+  const mention = /(?<![\w.])@bgagent(?![\w.])/gi;
+  if (!mention.test(body)) {
+    return { triggered: false, instruction: '' };
+  }
+
+  return {
+    triggered: true,
+    instruction: body
+      .replace(/(?<![\w.])@bgagent(?![\w.])/gi, ' ')
+      .replace(/[^\S\r\n]+/g, ' ')
+      .replace(/ *\r?\n */g, '\n')
+      .trim(),
+  };
+}
+
+/**
+ * ABCA-authored Jira comments use stable leading markers. Reject them before
+ * mention parsing so rendered help/examples can never create a self-trigger
+ * loop. Jira comments posted through 3LO are attributed to the authorizing
+ * Atlassian user rather than an app account, so author.accountType alone is
+ * insufficient as a loop guard.
+ */
+export function isKnownAbcaComment(body: string): boolean {
+  const prefixes = [
+    '🤖 ABCA ',
+    '✅ Task completed',
+    '❌ Task ',
+    '❌ ABCA ',
+    '⚠️ Shipped a PR but stopped early',
+    '👀 ABCA ',
+  ];
+  const trimmed = body.trimStart();
+  return prefixes.some((prefix) => trimmed.startsWith(prefix));
+}
+
+/** Build the instruction passed to the PR-iteration workflow. */
+export function buildIterationInstruction(trigger: CommentTrigger): string {
+  return trigger.instruction || 'Address the latest review feedback on this pull request.';
+}
diff --git a/cdk/src/handlers/shared/create-task-core.ts b/cdk/src/handlers/shared/create-task-core.ts
index 95c725e8..680aadf8 100644
--- a/cdk/src/handlers/shared/create-task-core.ts
+++ b/cdk/src/handlers/shared/create-task-core.ts
@@ -684,6 +684,16 @@ export async function createTaskCore(
     ...(context.idempotencyKey && { idempotency_key: context.idempotencyKey }),
     channel_source: context.channelSource,
     channel_metadata: context.channelMetadata,
+    // DynamoDB GSIs cannot key on nested map values. Hoist the tenant-scoped
+    // Jira issue identity so JiraIssueIndex can resolve comment triggers back
+    // to the newest PR-producing task.
+    ...(context.channelSource === 'jira'
+      && context.channelMetadata.jira_cloud_id
+      && context.channelMetadata.jira_issue_key
+      && {
+        jira_issue_identity:
+          `${context.channelMetadata.jira_cloud_id}#${context.channelMetadata.jira_issue_key}`,
+      }),
     ...(attachmentRecords.length > 0 && { attachments: attachmentRecords }),
     status_created_at: `${initialStatus}#${now}`,
     created_at: now,
diff --git a/cdk/src/handlers/shared/jira-adf.ts b/cdk/src/handlers/shared/jira-adf.ts
index e624f318..62322525 100644
--- a/cdk/src/handlers/shared/jira-adf.ts
+++ b/cdk/src/handlers/shared/jira-adf.ts
@@ -29,7 +29,7 @@
  * The full ADF spec has dozens of node types; rolling a complete converter
  * here would dwarf the rest of the integration and add a new dependency
  * surface. The agent gets a coherent text rendering; richer rendering (tables,
- * mentions) can land in a follow-up.
+ * text marks) can land in a follow-up.
  *
  * Tests: cdk/test/handlers/jira-webhook-processor.test.ts (via the processor)
  * and cdk/test/handlers/shared/jira-attachments.test.ts (comment rendering).
@@ -43,6 +43,8 @@ export interface AdfNode {
   readonly text?: string;
   readonly attrs?: {
     readonly level?: number;
+    /** `mention` node: rendered account label, including the leading `@`. */
+    readonly text?: string;
     /** `media` node: `"external"` carries a direct `url`; `"file"`/`"link"`
      *  carry an attachment `id` that needs a Jira API call to resolve. */
     readonly type?: string;
@@ -133,6 +135,9 @@ function walkAdf(node: AdfNode | undefined, out: string[], depth: number): void
     case 'text':
       if (node.text) out.push(node.text);
       return;
+    case 'mention':
+      if (node.attrs?.text) out.push(node.attrs.text);
+      return;
     default:
       // Unknown node — descend into its content if any so embedded text
       // (e.g. inside a panel or quote) isn't lost.
@@ -142,6 +147,8 @@ function walkAdf(node: AdfNode | undefined, out: string[], depth: number): void
 
 function textOf(node: AdfNode): string {
   if (node.type === 'text' && node.text) return node.text;
+  if (node.type === 'mention' && node.attrs?.text) return node.attrs.text;
+  if (node.type === 'hardBreak') return '\n';
   if (node.content) return node.content.map(textOf).join('');
   return '';
 }
diff --git a/cdk/src/handlers/shared/jira-task-by-issue.ts b/cdk/src/handlers/shared/jira-task-by-issue.ts
new file mode 100644
index 00000000..74e245af
--- /dev/null
+++ b/cdk/src/handlers/shared/jira-task-by-issue.ts
@@ -0,0 +1,110 @@
+/**
+ *  MIT No Attribution
+ *
+ *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy of
+ *  the Software without restriction, including without limitation the rights to
+ *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ *  the Software, and to permit persons to whom the Software is furnished to do so.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+import { type DynamoDBDocumentClient, QueryCommand } from '@aws-sdk/lib-dynamodb';
+import { JIRA_ISSUE_INDEX_NAME } from '../../constructs/task-table-indexes';
+
+const QUERY_PAGE_SIZE = 25;
+
+export interface JiraIssueTask {
+  readonly task_id: string;
+  readonly user_id?: string;
+  readonly repo?: string;
+  readonly pr_url?: string;
+  readonly pr_number?: number;
+  readonly status?: string;
+  readonly channel_metadata?: Record<string, string>;
+}
+
+/** Tenant-scoped sparse-index key for a Jira issue. */
+export function jiraIssueIdentity(cloudId: string, issueKey: string): string {
+  return `${cloudId}#${issueKey}`;
+}
+
+/**
+ * Resolve a Jira issue to its newest PR-producing ABCA task.
+ *
+ * Newer attempts that never opened a PR are skipped. Query pagination is
+ * required because DynamoDB applies Limit before any client-side selection;
+ * stopping after a PR-less first page could hide an older valid PR target.
+ */
+export async function resolveTaskByJiraIssue(
+  ddb: DynamoDBDocumentClient,
+  taskTableName: string,
+  cloudId: string,
+  issueKey: string,
+): Promise<JiraIssueTask | null> {
+  const identity = jiraIssueIdentity(cloudId, issueKey);
+  let exclusiveStartKey: Record<string, unknown> | undefined;
+
+  do {
+    const result = await ddb.send(new QueryCommand({
+      TableName: taskTableName,
+      IndexName: JIRA_ISSUE_INDEX_NAME,
+      KeyConditionExpression: 'jira_issue_identity = :identity',
+      ExpressionAttributeValues: { ':identity': identity },
+      ScanIndexForward: false,
+      Limit: QUERY_PAGE_SIZE,
+      ExclusiveStartKey: exclusiveStartKey,
+    }));
+
+    for (const item of result.Items ?? []) {
+      if (prNumberFromTask(item) === null || typeof item.task_id !== 'string') {
+        continue;
+      }
+      return {
+        task_id: item.task_id,
+        ...(typeof item.user_id === 'string' && { user_id: item.user_id }),
+        ...(typeof item.repo === 'string' && { repo: item.repo }),
+        ...(typeof item.pr_url === 'string' && { pr_url: item.pr_url }),
+        ...(typeof item.pr_number === 'number' && { pr_number: item.pr_number }),
+        ...(typeof item.status === 'string' && { status: item.status }),
+        ...(isStringRecord(item.channel_metadata) && { channel_metadata: item.channel_metadata }),
+      };
+    }
+    exclusiveStartKey = result.LastEvaluatedKey;
+  } while (exclusiveStartKey);
+
+  return null;
+}
+
+/** Extract a PR number from the canonical field or a persisted GitHub PR URL. */
+export function prNumberFromTask(task: { pr_number?: unknown; pr_url?: unknown }): number | null {
+  if (
+    typeof task.pr_number === 'number'
+    && Number.isInteger(task.pr_number)
+    && task.pr_number > 0
+  ) {
+    return task.pr_number;
+  }
+  if (typeof task.pr_url === 'string') {
+    const match = task.pr_url.match(/\/pull\/(\d+)\b/);
+    if (match) {
+      const parsed = Number(match[1]);
+      if (Number.isSafeInteger(parsed) && parsed > 0) return parsed;
+    }
+  }
+  return null;
+}
+
+function isStringRecord(value: unknown): value is Record<string, string> {
+  return typeof value === 'object'
+    && value !== null
+    && Object.values(value).every((entry) => typeof entry === 'string');
+}
diff --git a/cdk/src/handlers/shared/types.ts b/cdk/src/handlers/shared/types.ts
index dc4d9c84..cf29423c 100644
--- a/cdk/src/handlers/shared/types.ts
+++ b/cdk/src/handlers/shared/types.ts
@@ -99,6 +99,8 @@ export interface TaskRecord {
   readonly idempotency_key?: string;
   readonly channel_source: ChannelSource;
   readonly channel_metadata?: Record<string, string>;
+  /** Sparse JiraIssueIndex key (`{cloudId}#{issueKey}`); internal only. */
+  readonly jira_issue_identity?: string;
   readonly status_created_at: string;
   readonly created_at: string;
   readonly updated_at: string;
diff --git a/cdk/test/constructs/task-table.test.ts b/cdk/test/constructs/task-table.test.ts
index c9e58332..638d289e 100644
--- a/cdk/test/constructs/task-table.test.ts
+++ b/cdk/test/constructs/task-table.test.ts
@@ -19,7 +19,7 @@
 
 import { App, RemovalPolicy, Stack } from 'aws-cdk-lib';
 import { Match, Template } from 'aws-cdk-lib/assertions';
-import { TaskTable } from '../../src/constructs/task-table';
+import { JIRA_ISSUE_INDEX_NAME, TaskTable } from '../../src/constructs/task-table';
 
 describe('TaskTable', () => {
   let template: Template;
@@ -104,6 +104,31 @@ describe('TaskTable', () => {
     });
   });
 
+  test('creates sparse JiraIssueIndex GSI with the resolver projection', () => {
+    template.hasResourceProperties('AWS::DynamoDB::Table', {
+      GlobalSecondaryIndexes: Match.arrayWith([
+        Match.objectLike({
+          IndexName: 'JiraIssueIndex',
+          KeySchema: [
+            { AttributeName: 'jira_issue_identity', KeyType: 'HASH' },
+            { AttributeName: 'created_at', KeyType: 'RANGE' },
+          ],
+          Projection: {
+            ProjectionType: 'INCLUDE',
+            NonKeyAttributes: Match.arrayWith([
+              'pr_url',
+              'pr_number',
+              'status',
+              'repo',
+              'user_id',
+              'channel_metadata',
+            ]),
+          },
+        }),
+      ]),
+    });
+  });
+
   test('declares all required attribute definitions', () => {
     template.hasResourceProperties('AWS::DynamoDB::Table', {
       AttributeDefinitions: Match.arrayWith([
@@ -113,6 +138,7 @@ describe('TaskTable', () => {
         { AttributeName: 'status', AttributeType: 'S' },
         { AttributeName: 'created_at', AttributeType: 'S' },
         { AttributeName: 'idempotency_key', AttributeType: 'S' },
+        { AttributeName: 'jira_issue_identity', AttributeType: 'S' },
       ]),
     });
   });
@@ -130,6 +156,8 @@ describe('TaskTable', () => {
     expect(TaskTable.USER_STATUS_INDEX).toBe('UserStatusIndex');
     expect(TaskTable.STATUS_INDEX).toBe('StatusIndex');
     expect(TaskTable.IDEMPOTENCY_INDEX).toBe('IdempotencyIndex');
+    expect(TaskTable.JIRA_ISSUE_INDEX).toBe('JiraIssueIndex');
+    expect(JIRA_ISSUE_INDEX_NAME).toBe(TaskTable.JIRA_ISSUE_INDEX);
   });
 });
 
diff --git a/cdk/test/handlers/jira-webhook-processor.test.ts b/cdk/test/handlers/jira-webhook-processor.test.ts
index 4b7394d6..3ec35ab2 100644
--- a/cdk/test/handlers/jira-webhook-processor.test.ts
+++ b/cdk/test/handlers/jira-webhook-processor.test.ts
@@ -40,6 +40,15 @@ jest.mock('../../src/handlers/shared/jira-oauth-resolver', () => ({
   resolveJiraOauthToken: (...args: unknown[]) => resolveJiraOauthTokenMock(...args),
 }));
 
+const resolveTaskByJiraIssueMock = jest.fn();
+jest.mock('../../src/handlers/shared/jira-task-by-issue', () => {
+  const actual = jest.requireActual('../../src/handlers/shared/jira-task-by-issue');
+  return {
+    ...actual,
+    resolveTaskByJiraIssue: (...args: unknown[]) => resolveTaskByJiraIssueMock(...args),
+  };
+});
+
 // The processor screens the folded comment section via the Bedrock Guardrail
 // (fail-open on intervention). Mock the client so it passes by default; the
 // comment-block-dropped test overrides it to GUARDRAIL_INTERVENED.
@@ -68,6 +77,7 @@ jest.mock('../../src/handlers/shared/jira-attachments', () => {
 process.env.JIRA_PROJECT_MAPPING_TABLE_NAME = 'JiraProjects';
 process.env.JIRA_USER_MAPPING_TABLE_NAME = 'JiraUsers';
 process.env.JIRA_WORKSPACE_REGISTRY_TABLE_NAME = 'JiraWorkspaceRegistry';
+process.env.TASK_TABLE_NAME = 'Tasks';
 // Attachment enrichment needs a bucket + guardrail configured (#577); with
 // these set the processor initializes S3/Bedrock clients (cheap, no network at
 // construction) and screens attachments through the mocked helper.
@@ -111,6 +121,39 @@ function issue(overrides: Record<string, unknown> = {}): Record<string, unknown>
   };
 }
 
+function comment(overrides: Record<string, unknown> = {}): Record<string, unknown> {
+  return {
+    webhookEvent: 'comment_created',
+    timestamp: 1784079623761,
+    cloudId: 'cloud-1',
+    user: { accountId: 'reviewer-1', displayName: 'Reviewer' },
+    issue: {
+      id: '10001',
+      key: 'ENG-42',
+      fields: { project: { id: 'p1', key: 'ENG' } },
+    },
+    comment: {
+      id: 'comment-1',
+      author: {
+        accountId: 'reviewer-1',
+        accountType: 'atlassian',
+        displayName: 'Reviewer',
+      },
+      body: {
+        type: 'doc',
+        version: 1,
+        content: [
+          {
+            type: 'paragraph',
+            content: [{ type: 'text', text: '@bgagent update the README too' }],
+          },
+        ],
+      },
+    },
+    ...overrides,
+  };
+}
+
 describe('jira-webhook-processor handler', () => {
   beforeEach(() => {
     ddbSend.mockReset();
@@ -126,6 +169,8 @@ describe('jira-webhook-processor handler', () => {
       siteUrl: 'https://acme.atlassian.net',
       oauthSecretArn: 'arn:aws:secretsmanager:us-east-1:123:secret:bgagent-jira-oauth-cloud-1',
     });
+    resolveTaskByJiraIssueMock.mockReset();
+    resolveTaskByJiraIssueMock.mockResolvedValue(null);
     // Default (#577): no comments, no attachments. Per-case tests override.
     fetchRecentHumanCommentsMock.mockReset();
     fetchRecentHumanCommentsMock.mockResolvedValue([]);
@@ -146,11 +191,271 @@ describe('jira-webhook-processor handler', () => {
     expect(createTaskCoreMock).not.toHaveBeenCalled();
   });
 
-  test('skips non-issue webhookEvent', async () => {
-    await handler(eventWith({ webhookEvent: 'comment_created', issue: { id: 'x', key: 'X-1' } }));
+  test('skips unsupported webhookEvent', async () => {
+    await handler(eventWith({ webhookEvent: 'comment_updated', issue: { id: 'x', key: 'X-1' } }));
     expect(createTaskCoreMock).not.toHaveBeenCalled();
   });
 
+  describe('comment-triggered PR iteration', () => {
+    const priorTask = {
+      task_id: 'prior-task',
+      user_id: 'original-owner',
+      repo: 'org/repo',
+      pr_number: 42,
+      status: 'COMPLETED',
+      channel_metadata: {
+        jira_cloud_id: 'cloud-1',
+        jira_project_key: 'ENG',
+        jira_issue_id: '10001',
+        jira_issue_key: 'ENG-42',
+        jira_status_on_start: 'Doing',
+        jira_status_on_pr: 'Code Review',
+      },
+    };
+
+    test('ADF @bgagent comment creates a PR iteration for the linked comment author', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({
+        Item: { platform_user_id: 'linked-reviewer', status: 'active' },
+      });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 201, body: '{}' });
+
+      await handler(eventWith(comment()));
+
+      expect(resolveTaskByJiraIssueMock).toHaveBeenCalledWith(
+        expect.anything(),
+        'Tasks',
+        'cloud-1',
+        'ENG-42',
+      );
+      expect(createTaskCoreMock).toHaveBeenCalledTimes(1);
+      const [request, context] = createTaskCoreMock.mock.calls[0];
+      expect(request).toEqual({
+        repo: 'org/repo',
+        workflow_ref: 'coding/pr-iteration-v1',
+        pr_number: 42,
+        task_description: 'update the README too',
+      });
+      expect(context.userId).toBe('linked-reviewer');
+      expect(context.channelSource).toBe('jira');
+      expect(context.idempotencyKey).toMatch(/^jira-iterate-[a-f0-9]{64}$/);
+      expect(context.channelMetadata).toMatchObject({
+        jira_cloud_id: 'cloud-1',
+        jira_project_key: 'ENG',
+        jira_issue_id: '10001',
+        jira_issue_key: 'ENG-42',
+        jira_status_on_start: 'Doing',
+        jira_status_on_pr: 'Code Review',
+        jira_trigger_comment_id: 'comment-1',
+        jira_prior_task_id: 'prior-task',
+        jira_oauth_secret_arn:
+          'arn:aws:secretsmanager:us-east-1:123:secret:bgagent-jira-oauth-cloud-1',
+      });
+      expect(reportIssueFailureMock).toHaveBeenCalledWith(
+        expect.anything(),
+        'ENG-42',
+        '👀 ABCA accepted this follow-up and is updating PR #42.',
+      );
+      // Comment triggers route from the prior task, not the current project
+      // mapping or label state. The only DDB Get is author attribution.
+      expect(ddbSend.mock.calls).toHaveLength(1);
+      expect(ddbSend.mock.calls[0][0].input.Key)
+        .toEqual({ jira_identity: 'cloud-1#reviewer-1' });
+    });
+
+    test('ADF mention node creates a PR iteration', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 201, body: '{}' });
+      const payload = comment();
+      (payload.comment as Record<string, unknown>).body = {
+        type: 'doc',
+        version: 1,
+        content: [{
+          type: 'paragraph',
+          content: [
+            {
+              type: 'mention',
+              attrs: { id: 'bgagent-account', text: '@bgagent' },
+            },
+            { type: 'text', text: ' handle the null case' },
+          ],
+        }],
+      };
+
+      await handler(eventWith(payload));
+
+      expect(createTaskCoreMock).toHaveBeenCalledTimes(1);
+      expect(createTaskCoreMock.mock.calls[0][0].task_description)
+        .toBe('handle the null case');
+    });
+
+    test('preserves ADF hard breaks in a multiline instruction', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 201, body: '{}' });
+      const payload = comment();
+      (payload.comment as Record<string, unknown>).body = {
+        type: 'doc',
+        version: 1,
+        content: [{
+          type: 'paragraph',
+          content: [
+            { type: 'text', text: '@bgagent please:' },
+            { type: 'hardBreak' },
+            { type: 'text', text: '- update docs' },
+            { type: 'hardBreak' },
+            { type: 'text', text: '- add a test' },
+          ],
+        }],
+      };
+
+      await handler(eventWith(payload));
+
+      expect(createTaskCoreMock.mock.calls[0][0].task_description)
+        .toBe('please:\n- update docs\n- add a test');
+    });
+
+    test('plain-text comment falls back to the original task owner when author is unlinked', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce({
+        ...priorTask,
+        pr_number: undefined,
+        pr_url: 'https://github.com/org/repo/pull/73',
+      });
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 201, body: '{}' });
+      const payload = comment();
+      (payload.comment as Record<string, unknown>).body = '@bgagent rename the flag';
+
+      await handler(eventWith(payload));
+
+      const [request, context] = createTaskCoreMock.mock.calls[0];
+      expect(request.pr_number).toBe(73);
+      expect(request.task_description).toBe('rename the flag');
+      expect(context.userId).toBe('original-owner');
+    });
+
+    test('bare mention uses the latest-review fallback instruction', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 201, body: '{}' });
+      const payload = comment();
+      (payload.comment as Record<string, unknown>).body = '@bgagent';
+
+      await handler(eventWith(payload));
+
+      const [request] = createTaskCoreMock.mock.calls[0];
+      expect(request.task_description)
+        .toBe('Address the latest review feedback on this pull request.');
+    });
+
+    test('comment without @bgagent is a no-op', async () => {
+      const payload = comment();
+      (payload.comment as Record<string, unknown>).body = 'Looks good to me';
+
+      await handler(eventWith(payload));
+
+      expect(resolveTaskByJiraIssueMock).not.toHaveBeenCalled();
+      expect(createTaskCoreMock).not.toHaveBeenCalled();
+      expect(reportIssueFailureMock).not.toHaveBeenCalled();
+    });
+
+    test.each([
+      {
+        author: { accountId: 'app-1', accountType: 'app' },
+        body: '@bgagent update the README',
+      },
+      {
+        author: { accountId: 'reviewer-1', accountType: 'atlassian' },
+        body: '🤖 ABCA picked up this issue. Example: @bgagent update the README',
+      },
+    ])('app/self comment is ignored: %o', async ({ author, body }) => {
+      const payload = comment();
+      (payload.comment as Record<string, unknown>).author = author;
+      (payload.comment as Record<string, unknown>).body = body;
+
+      await handler(eventWith(payload));
+
+      expect(resolveTaskByJiraIssueMock).not.toHaveBeenCalled();
+      expect(createTaskCoreMock).not.toHaveBeenCalled();
+    });
+
+    test('posts clear feedback when no prior PR-producing task exists', async () => {
+      await handler(eventWith(comment()));
+
+      expect(createTaskCoreMock).not.toHaveBeenCalled();
+      expect(reportIssueFailureMock).toHaveBeenCalledTimes(1);
+      expect(reportIssueFailureMock.mock.calls[0][2]).toContain(
+        "couldn't find an ABCA pull request",
+      );
+    });
+
+    test('propagates task lookup failures for asynchronous retry', async () => {
+      resolveTaskByJiraIssueMock.mockRejectedValueOnce(new Error('DynamoDB unavailable'));
+
+      await expect(handler(eventWith(comment()))).rejects.toThrow('DynamoDB unavailable');
+
+      expect(createTaskCoreMock).not.toHaveBeenCalled();
+      expect(reportIssueFailureMock).not.toHaveBeenCalled();
+    });
+
+    test('unattributable prior task posts feedback instead of creating a task', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce({
+        ...priorTask,
+        user_id: undefined,
+      });
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+
+      await handler(eventWith(comment()));
+
+      expect(createTaskCoreMock).not.toHaveBeenCalled();
+      expect(reportIssueFailureMock.mock.calls[0][2]).toContain('linked ABCA user');
+    });
+
+    test('idempotent replay creates no duplicate task acknowledgement', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 200, body: '{}' });
+
+      await handler(eventWith(comment()));
+
+      expect(createTaskCoreMock).toHaveBeenCalledTimes(1);
+      expect(reportIssueFailureMock).not.toHaveBeenCalled();
+    });
+
+    test('task admission failure is reported instead of acknowledged', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({
+        statusCode: 400,
+        body: JSON.stringify({
+          error: { message: 'Task description was blocked by content policy.' },
+        }),
+      });
+
+      await handler(eventWith(comment()));
+
+      expect(reportIssueFailureMock).toHaveBeenCalledTimes(1);
+      expect(reportIssueFailureMock.mock.calls[0][2]).toContain(
+        'blocked by content policy',
+      );
+      expect(reportIssueFailureMock.mock.calls[0][2]).not.toContain('accepted this follow-up');
+    });
+
+    test('transient admission failure tells the reviewer to post a new comment', async () => {
+      resolveTaskByJiraIssueMock.mockResolvedValueOnce(priorTask);
+      ddbSend.mockResolvedValueOnce({ Item: undefined });
+      createTaskCoreMock.mockResolvedValueOnce({ statusCode: 503, body: '{}' });
+
+      await handler(eventWith(comment()));
+
+      const message = reportIssueFailureMock.mock.calls[0][2] as string;
+      expect(message).toContain('temporarily unavailable');
+      expect(message).toContain('add a new `@bgagent` comment');
+      expect(message).not.toContain('re-apply the trigger label');
+    });
+  });
+
   test('skips when issue.id or issue.key is missing', async () => {
     await handler(eventWith({ webhookEvent: 'jira:issue_created' }));
     expect(createTaskCoreMock).not.toHaveBeenCalled();
diff --git a/cdk/test/handlers/jira-webhook.test.ts b/cdk/test/handlers/jira-webhook.test.ts
index 4186ae9a..8e7fb779 100644
--- a/cdk/test/handlers/jira-webhook.test.ts
+++ b/cdk/test/handlers/jira-webhook.test.ts
@@ -107,6 +107,20 @@ function issueCreatePayload(overrides: Record<string, unknown> = {}): string {
   });
 }
 
+function commentCreatePayload(overrides: Record<string, unknown> = {}): string {
+  return JSON.stringify({
+    webhookEvent: 'comment_created',
+    timestamp: Date.now(),
+    issue: {
+      id: '10001',
+      key: 'ENG-42',
+      fields: { project: { id: 'p1', key: 'ENG' } },
+    },
+    comment: { id: 'comment-1' },
+    ...overrides,
+  });
+}
+
 describe('jira-webhook handler', () => {
   beforeEach(() => {
     ddbSend.mockReset();
@@ -134,9 +148,9 @@ describe('jira-webhook handler', () => {
     expect(lambdaSend).not.toHaveBeenCalled();
   });
 
-  test('ignores non-Issue webhookEvent types with 200', async () => {
+  test('ignores unsupported webhookEvent types with 200', async () => {
     const body = JSON.stringify({
-      webhookEvent: 'comment_created',
+      webhookEvent: 'comment_updated',
       timestamp: Date.now(),
       comment: { id: 'c-1' },
     });
@@ -146,6 +160,48 @@ describe('jira-webhook handler', () => {
     expect(lambdaSend).not.toHaveBeenCalled();
   });
 
+  test('verified comment_created event dedups by comment id and invokes processor', async () => {
+    const body = commentCreatePayload();
+    ddbSend.mockResolvedValueOnce({});
+    lambdaSend.mockResolvedValueOnce({});
+
+    const result = await handler(makeEvent(body, sign(body)));
+
+    expect(result.statusCode).toBe(200);
+    const putCall = ddbSend.mock.calls.find(([cmd]) => cmd._type === 'Put');
+    expect(putCall![0].input.Item.dedup_key)
+      .toBe('ENG-42#comment_created#comment-1');
+    const invokeCall = lambdaSend.mock.calls[0][0];
+    const decoded = JSON.parse(new TextDecoder().decode(invokeCall.input.Payload));
+    expect(decoded.raw_body).toBe(body);
+  });
+
+  test('distinct comments do not collapse even when their timestamps match', async () => {
+    const timestamp = Date.now();
+    const body1 = commentCreatePayload({ timestamp, comment: { id: 'comment-1' } });
+    const body2 = commentCreatePayload({ timestamp, comment: { id: 'comment-2' } });
+    ddbSend.mockResolvedValue({});
+    lambdaSend.mockResolvedValue({});
+
+    await handler(makeEvent(body1, sign(body1)));
+    await handler(makeEvent(body2, sign(body2)));
+
+    const putCalls = ddbSend.mock.calls.filter(([cmd]) => cmd._type === 'Put');
+    expect(putCalls.map(([cmd]) => cmd.input.Item.dedup_key)).toEqual([
+      'ENG-42#comment_created#comment-1',
+      'ENG-42#comment_created#comment-2',
+    ]);
+  });
+
+  test('400s when a verified comment_created event has no comment.id', async () => {
+    const body = commentCreatePayload({ comment: {} });
+    const result = await handler(makeEvent(body, sign(body)));
+
+    expect(result.statusCode).toBe(400);
+    expect(ddbSend).not.toHaveBeenCalled();
+    expect(lambdaSend).not.toHaveBeenCalled();
+  });
+
   test('400s when issue.id or issue.key is missing on a verified Issue event', async () => {
     const body = JSON.stringify({
       webhookEvent: 'jira:issue_created',
diff --git a/cdk/test/handlers/shared/comment-trigger.test.ts b/cdk/test/handlers/shared/comment-trigger.test.ts
new file mode 100644
index 00000000..613adba1
--- /dev/null
+++ b/cdk/test/handlers/shared/comment-trigger.test.ts
@@ -0,0 +1,93 @@
+/**
+ *  MIT No Attribution
+ *
+ *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy of
+ *  the Software without restriction, including without limitation the rights to
+ *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ *  the Software, and to permit persons to whom the Software is furnished to do so.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+import {
+  buildIterationInstruction,
+  isKnownAbcaComment,
+  parseCommentTrigger,
+} from '../../../src/handlers/shared/comment-trigger';
+
+describe('parseCommentTrigger', () => {
+  test('extracts instruction text after a token-bounded mention', () => {
+    expect(parseCommentTrigger('Please @bgagent update the README too')).toEqual({
+      triggered: true,
+      instruction: 'Please update the README too',
+    });
+  });
+
+  test('matches case-insensitively and removes every occurrence', () => {
+    expect(parseCommentTrigger('@BgAgent do X and @bgagent also Y')).toEqual({
+      triggered: true,
+      instruction: 'do X and also Y',
+    });
+  });
+
+  test('preserves multiline reviewer instructions', () => {
+    expect(parseCommentTrigger('@bgagent please:\n- update docs\n- add a test')).toEqual({
+      triggered: true,
+      instruction: 'please:\n- update docs\n- add a test',
+    });
+  });
+
+  test('accepts a bare mention with an empty instruction', () => {
+    expect(parseCommentTrigger('@bgagent')).toEqual({
+      triggered: true,
+      instruction: '',
+    });
+  });
+
+  test.each([
+    'ping @bgagentbot',
+    'email foo@bgagent.io',
+    'handle-like prefix foo@bgagent fix it',
+    'ordinary human discussion',
+    '',
+  ])('does not trigger on %p', (body) => {
+    expect(parseCommentTrigger(body).triggered).toBe(false);
+  });
+
+  test.each([
+    '🤖 ABCA started. Example: @bgagent fix it',
+    '✅ Task completed. @bgagent',
+    '❌ ABCA could not create the task. @bgagent retry',
+    '👀 ABCA accepted this follow-up. @bgagent',
+  ])('does not trigger on known ABCA-rendered comment %p', (body) => {
+    expect(parseCommentTrigger(body).triggered).toBe(false);
+    expect(isKnownAbcaComment(body)).toBe(true);
+  });
+
+  test('does not treat a human status emoji as proof that ABCA authored the comment', () => {
+    expect(parseCommentTrigger('✅ @bgagent ship the documentation update')).toEqual({
+      triggered: true,
+      instruction: '✅ ship the documentation update',
+    });
+  });
+});
+
+describe('buildIterationInstruction', () => {
+  test('uses explicit reviewer instructions', () => {
+    expect(buildIterationInstruction({ triggered: true, instruction: 'Rename the flag' }))
+      .toBe('Rename the flag');
+  });
+
+  test('uses review-feedback fallback for a bare mention', () => {
+    expect(buildIterationInstruction({ triggered: true, instruction: '' }))
+      .toBe('Address the latest review feedback on this pull request.');
+  });
+});
diff --git a/cdk/test/handlers/shared/create-task-core.test.ts b/cdk/test/handlers/shared/create-task-core.test.ts
index 0c49aa20..6eba74b1 100644
--- a/cdk/test/handlers/shared/create-task-core.test.ts
+++ b/cdk/test/handlers/shared/create-task-core.test.ts
@@ -114,6 +114,45 @@ describe('createTaskCore', () => {
     expect(mockLambdaSend).toHaveBeenCalledTimes(1);
   });
 
+  test('hoists tenant-scoped Jira issue identity for the sparse lookup index', async () => {
+    const result = await createTaskCore(
+      { repo: 'org/repo', task_description: 'Fix the Jira issue' },
+      makeContext({
+        channelSource: 'jira',
+        channelMetadata: {
+          jira_cloud_id: 'cloud-1',
+          jira_issue_key: 'ENG-42',
+        },
+      }),
+      'req-jira-identity',
+    );
+
+    expect(result.statusCode).toBe(201);
+    const taskPut = mockSend.mock.calls.find(
+      ([command]) => command._type === 'Put' && command.input.TableName === 'Tasks',
+    );
+    expect(taskPut![0].input.Item.jira_issue_identity).toBe('cloud-1#ENG-42');
+  });
+
+  test('does not hoist Jira issue identity for incomplete or non-Jira metadata', async () => {
+    await createTaskCore(
+      { repo: 'org/repo', task_description: 'Regular task' },
+      makeContext({
+        channelSource: 'api',
+        channelMetadata: {
+          jira_cloud_id: 'cloud-1',
+          jira_issue_key: 'ENG-42',
+        },
+      }),
+      'req-no-jira-identity',
+    );
+
+    const taskPut = mockSend.mock.calls.find(
+      ([command]) => command._type === 'Put' && command.input.TableName === 'Tasks',
+    );
+    expect(taskPut![0].input.Item).not.toHaveProperty('jira_issue_identity');
+  });
+
   test('accepts an initial_approvals pattern whose value contains a colon', async () => {
     // Regression: the degenerate-pattern guard used split(':', 2)[1], which
     // truncated the value at the next colon. For "ab:cdefgh" that yields the
diff --git a/cdk/test/handlers/shared/jira-task-by-issue.test.ts b/cdk/test/handlers/shared/jira-task-by-issue.test.ts
new file mode 100644
index 00000000..c15a1cf8
--- /dev/null
+++ b/cdk/test/handlers/shared/jira-task-by-issue.test.ts
@@ -0,0 +1,113 @@
+/**
+ *  MIT No Attribution
+ *
+ *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy of
+ *  the Software without restriction, including without limitation the rights to
+ *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ *  the Software, and to permit persons to whom the Software is furnished to do so.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+const send = jest.fn();
+jest.mock('@aws-sdk/lib-dynamodb', () => ({
+  QueryCommand: jest.fn((input: unknown) => ({ _type: 'Query', input })),
+}));
+
+import type { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';
+import {
+  jiraIssueIdentity,
+  prNumberFromTask,
+  resolveTaskByJiraIssue,
+} from '../../../src/handlers/shared/jira-task-by-issue';
+
+const ddb = { send } as unknown as DynamoDBDocumentClient;
+
+beforeEach(() => {
+  send.mockReset();
+});
+
+test('builds a tenant-scoped Jira issue identity', () => {
+  expect(jiraIssueIdentity('cloud-1', 'ENG-42')).toBe('cloud-1#ENG-42');
+});
+
+test('returns the newest PR-producing task and uses JiraIssueIndex', async () => {
+  send.mockResolvedValueOnce({
+    Items: [{
+      task_id: 'task-2',
+      user_id: 'user-1',
+      repo: 'org/repo',
+      pr_number: 42,
+      status: 'COMPLETED',
+      channel_metadata: { jira_cloud_id: 'cloud-1', jira_issue_key: 'ENG-42' },
+    }],
+  });
+
+  const result = await resolveTaskByJiraIssue(ddb, 'Tasks', 'cloud-1', 'ENG-42');
+
+  expect(result).toMatchObject({ task_id: 'task-2', pr_number: 42, repo: 'org/repo' });
+  expect(send.mock.calls[0][0].input).toMatchObject({
+    TableName: 'Tasks',
+    IndexName: 'JiraIssueIndex',
+    ExpressionAttributeValues: { ':identity': 'cloud-1#ENG-42' },
+    ScanIndexForward: false,
+  });
+});
+
+test('skips newer PR-less tasks on the same page', async () => {
+  send.mockResolvedValueOnce({
+    Items: [
+      { task_id: 'task-new', repo: 'org/repo' },
+      { task_id: 'task-pr', repo: 'org/repo', pr_url: 'https://github.com/org/repo/pull/18' },
+    ],
+  });
+
+  await expect(resolveTaskByJiraIssue(ddb, 'Tasks', 'cloud-1', 'ENG-42'))
+    .resolves.toMatchObject({ task_id: 'task-pr', pr_url: expect.stringContaining('/pull/18') });
+});
+
+test('paginates past a PR-less first page', async () => {
+  send
+    .mockResolvedValueOnce({
+      Items: [{ task_id: 'task-new', repo: 'org/repo' }],
+      LastEvaluatedKey: { jira_issue_identity: 'cloud-1#ENG-42', created_at: '2026-01-02' },
+    })
+    .mockResolvedValueOnce({
+      Items: [{ task_id: 'task-pr', repo: 'org/repo', pr_number: 17 }],
+    });
+
+  await expect(resolveTaskByJiraIssue(ddb, 'Tasks', 'cloud-1', 'ENG-42'))
+    .resolves.toMatchObject({ task_id: 'task-pr', pr_number: 17 });
+  expect(send).toHaveBeenCalledTimes(2);
+  expect(send.mock.calls[1][0].input.ExclusiveStartKey).toEqual({
+    jira_issue_identity: 'cloud-1#ENG-42',
+    created_at: '2026-01-02',
+  });
+});
+
+test('returns null when no PR-producing task exists', async () => {
+  send.mockResolvedValueOnce({ Items: [{ task_id: 'task-new' }] });
+  await expect(resolveTaskByJiraIssue(ddb, 'Tasks', 'cloud-1', 'ENG-42')).resolves.toBeNull();
+});
+
+test('propagates query failures so the async processor can retry', async () => {
+  send.mockRejectedValueOnce(new Error('DynamoDB unavailable'));
+  await expect(resolveTaskByJiraIssue(ddb, 'Tasks', 'cloud-1', 'ENG-42'))
+    .rejects.toThrow('DynamoDB unavailable');
+});
+
+test.each([
+  [{ pr_number: 12 }, 12],
+  [{ pr_url: 'https://github.com/o/r/pull/99/files' }, 99],
+  [{ pr_number: 0, pr_url: 'not-a-pr' }, null],
+])('prNumberFromTask(%o) returns %p', (task, expected) => {
+  expect(prNumberFromTask(task)).toBe(expected);
+});
diff --git a/cli/src/commands/jira.ts b/cli/src/commands/jira.ts
index 97a486fc..b813fd44 100644
--- a/cli/src/commands/jira.ts
+++ b/cli/src/commands/jira.ts
@@ -672,7 +672,7 @@ export function makeJiraCommand(): Command {
         console.log('  Webhook signing secret needed for THIS tenant.');
         console.log('  In Jira → Settings → System → Webhooks → Create a Webhook:');
         console.log(`    URL:           ${apiBaseUrl}/jira/webhook`);
-        console.log('    Events:        Issue: created, updated');
+        console.log('    Events:        Issue: created, Issue: updated, Comment: created');
         console.log('    Secret:        choose a strong random value (e.g. `openssl rand -hex 32`)');
         console.log();
         const webhookSigningSecret = await promptSecret('Webhook signing secret: ');
diff --git a/docs/guides/JIRA_SETUP_GUIDE.md b/docs/guides/JIRA_SETUP_GUIDE.md
index 80c82ce6..d2c4e736 100644
--- a/docs/guides/JIRA_SETUP_GUIDE.md
+++ b/docs/guides/JIRA_SETUP_GUIDE.md
@@ -1,6 +1,6 @@
 # Jira integration setup guide
 
-Set up the ABCA Jira Cloud integration so that adding a label to a Jira issue triggers an autonomous task. ABCA posts progress comments back on the issue as it works — a "started" comment from the agent and a final status comment (with cost, turns, and duration) from the platform when the task finishes.
+Set up the ABCA Jira Cloud integration so that adding a label to a Jira issue triggers an autonomous task. After ABCA opens a pull request, reviewers can comment `@bgagent <instruction>` on the same Jira issue to request another iteration. ABCA posts progress comments back on the issue as it works — a "started" comment from the agent and a final status comment (with cost, turns, and duration) from the platform when the task finishes.
 
 ## Prerequisites
 
@@ -13,7 +13,7 @@ Set up the ABCA Jira Cloud integration so that adding a label to a Jira issue tr
 
 ## How it works
 
-A Jira-site admin creates an Atlassian OAuth 2.0 (3LO) app and authorizes it on the site. The OAuth token bundle is stored in a per-tenant Secrets Manager secret (`bgagent-jira-oauth-<cloudId>`). When a user adds the trigger label to a Jira issue, Jira fires a webhook to ABCA; the receiver verifies the `X-Hub-Signature` HMAC, dedupes, and async-invokes the processor, which resolves the tenant, looks up the project→repo mapping, enriches the task with the issue's recent comments and screened file attachments (see [Issue context](#issue-context-attachments-and-comments)), and creates a task. Jira-triggered tasks always run the `coding/new-task-v1` workflow (the processor pins `workflow_ref` explicitly, since a label-triggered task always targets a mapped repo). The agent clones the repo, opens a PR, and posts a "started" comment on the Jira issue via the Jira REST v3 API (using the same stored OAuth token). When the task reaches a terminal state, the platform's fan-out plane posts a single final status comment — outcome, cost, turns, duration, and PR link — via the same REST v3 endpoint (see [How it works](#how-it-works) below).
+A Jira-site admin creates an Atlassian OAuth 2.0 (3LO) app and authorizes it on the site. The OAuth token bundle is stored in a per-tenant Secrets Manager secret (`bgagent-jira-oauth-<cloudId>`). When a user adds the trigger label to a Jira issue, Jira fires a webhook to ABCA; the receiver verifies the `X-Hub-Signature` HMAC, dedupes, and async-invokes the processor, which resolves the tenant, looks up the project→repo mapping, enriches the task with the issue's recent comments and screened file attachments (see [Issue context](#issue-context-attachments-and-comments)), and creates a task. Jira-triggered tasks always run the `coding/new-task-v1` workflow (the processor pins `workflow_ref` explicitly, since a label-triggered task always targets a mapped repo). A later `@bgagent` comment resolves that Jira issue to its most recent ABCA pull request and runs `coding/pr-iteration-v1` against the same PR. The agent clones the repo, opens or updates the PR, and posts a "started" comment on the Jira issue via the Jira REST v3 API (using the same stored OAuth token). When the task reaches a terminal state, the platform's fan-out plane posts a single final status comment — outcome, cost, turns, duration, and PR link — via the same REST v3 endpoint (see [How it works](#how-it-works) below).
 
 **Tenant key.** Everything is indexed on `cloudId` — the Atlassian tenant UUID, *not* the site domain or name. Webhook payloads and the OAuth flow both surface `cloudId`; it is the join key across the project-mapping, user-mapping, and workspace-registry tables.
 
@@ -131,7 +131,7 @@ This runs the OAuth 3LO dance:
 `setup` then prompts for a **webhook signing secret**. Unlike Linear, Atlassian does **not** auto-generate one — the operator chooses it at webhook-create time. In a second terminal, open **Jira → Settings → System → Webhooks → Create a Webhook** and enter:
 
 - **URL** — the `…/jira/webhook` URL that `setup` prints
-- **Events** — *Issue: created* and *Issue: updated*
+- **Events** — *Issue: created*, *Issue: updated*, and *Comment: created*
 - **Secret** — a strong random value, e.g. `openssl rand -hex 32`
 
 Paste that same secret value back at the `Webhook signing secret:` prompt. ABCA stores it on the per-tenant OAuth bundle (and mirrors it stack-wide), and the receiver looks it up to verify `X-Hub-Signature` on each delivery.
@@ -180,6 +180,8 @@ The teammate needs their own ABCA account first (Cognito user + configured CLI).
 
 Add the trigger label (`bgagent` by default) to a Jira issue in a mapped project. The agent should start within ~30 seconds, comment on the issue as it works, and post a PR link when ready. The issue **summary** plus the **description** (converted from Atlassian Document Format to markdown), the issue's **recent comments**, and any supported **file attachments** become the task context — see [Issue context: attachments and comments](#issue-context-attachments-and-comments).
 
+After the PR exists, add a Jira comment such as `@bgagent update the README too`. ABCA should acknowledge the request on the issue and update the existing PR.
+
 ## How webhook signature verification works
 
 Atlassian signs each delivery with HMAC-SHA256 over the **raw request body**, delivered as `X-Hub-Signature: sha256=<hex>`. The receiver:
@@ -194,8 +196,19 @@ The body must be verified as the *raw unparsed bytes* — never parsed-and-restr
 
 - **`jira:issue_created`** — triggers if the trigger label is already present on the new issue.
 - **`jira:issue_updated`** — triggers only if the label was **newly added** in this update. Jira reports label changes in `changelog.items[]` (`field: "labels"`, with `fromString` / `toString`), *not* by re-sending the full label list. The processor diffs the changelog rather than inspecting `issue.fields.labels`, so re-saving an issue that already has the label does not re-trigger.
+- **`comment_created`** — triggers only when the new comment contains a token-bounded `@bgagent` mention and the issue has a prior ABCA pull request.
 - All other event types get a silent `200`.
 
+## Comment-triggered PR iteration
+
+A `comment_created` webhook starts a PR iteration only when the comment contains the token-bounded mention `@bgagent` (case-insensitive). The remaining comment text becomes the `coding/pr-iteration-v1` instruction. A bare `@bgagent` asks the agent to address the latest PR review feedback.
+
+ABCA resolves the Jira tenant and issue key to the newest prior task that actually opened a PR. Newer attempts without a PR do not hide an older valid PR target. If no ABCA PR exists, ABCA posts a clear comment and creates no task.
+
+When the comment author has linked their Jira and ABCA accounts, the iteration is attributed to that user. Otherwise, ABCA falls back to the original task owner so a useful reviewer request is not dropped. Comments without the mention, app-authored comments, and ABCA's own generated status comments are no-ops.
+
+The acknowledgement is immediate after task admission. The existing platform fan-out path posts the terminal outcome and cost comment when the iteration finishes. Comment redelivery is idempotent: the webhook receiver deduplicates by Jira comment ID, and task creation uses a deterministic idempotency key as a second guard.
+
 ## Issue context: attachments and comments
 
 Beyond the summary and description, the processor enriches the task with the practical context a Jira ticket usually carries — attached files and recent clarifications — so the agent isn't left guessing at "see the attached log" or an acceptance detail buried in a comment. Both are fetched **authenticated at task-admission time** using the tenant's existing `read:jira-work` scope (**no new OAuth scopes, no re-authorization**), because a headless agent can't fetch them itself.
@@ -242,11 +255,12 @@ The feature targets Jira **statuses**, not board columns. Because moving a card
 
 ## Webhook dedup
 
-The receiver dedupes on `{issueKey}#{webhookEventTimestamp}` with an 8-hour TTL. Using the event timestamp (rather than event type) means two distinct label-adds in quick succession are not collapsed. Jira retries far less aggressively than Linear, so 8 hours is safe parity.
+The receiver dedupes issue events on `{issueKey}#{webhookEvent}#{timestamp}` and comment-created events on `{issueKey}#comment_created#{commentId}`, with an 8-hour TTL. The timestamp keeps distinct label additions separate; the stable comment ID collapses redelivery without merging separate comments. Jira retries far less aggressively than Linear, so 8 hours is safe parity.
 
 ## Usage
 
 - **Trigger a task**: add the trigger label to an issue in a mapped Jira project.
+- **Iterate on its PR**: comment `@bgagent <change>` on the Jira issue after ABCA has opened a PR.
 - **Check status**: from the Jira issue (progress comments) or `bgagent list` / `bgagent status <task-id>`.
 - **Cancel**: `bgagent cancel <task-id>`. Removing the Jira label does not cancel a running task.
 
diff --git a/docs/src/content/docs/using/Jira-setup-guide.md b/docs/src/content/docs/using/Jira-setup-guide.md
index 6c5643c6..f8ddf1e2 100644
--- a/docs/src/content/docs/using/Jira-setup-guide.md
+++ b/docs/src/content/docs/using/Jira-setup-guide.md
@@ -4,7 +4,7 @@ title: Jira setup guide
 
 # Jira integration setup guide
 
-Set up the ABCA Jira Cloud integration so that adding a label to a Jira issue triggers an autonomous task. ABCA posts progress comments back on the issue as it works — a "started" comment from the agent and a final status comment (with cost, turns, and duration) from the platform when the task finishes.
+Set up the ABCA Jira Cloud integration so that adding a label to a Jira issue triggers an autonomous task. After ABCA opens a pull request, reviewers can comment `@bgagent <instruction>` on the same Jira issue to request another iteration. ABCA posts progress comments back on the issue as it works — a "started" comment from the agent and a final status comment (with cost, turns, and duration) from the platform when the task finishes.
 
 ## Prerequisites
 
@@ -17,7 +17,7 @@ Set up the ABCA Jira Cloud integration so that adding a label to a Jira issue tr
 
 ## How it works
 
-A Jira-site admin creates an Atlassian OAuth 2.0 (3LO) app and authorizes it on the site. The OAuth token bundle is stored in a per-tenant Secrets Manager secret (`bgagent-jira-oauth-<cloudId>`). When a user adds the trigger label to a Jira issue, Jira fires a webhook to ABCA; the receiver verifies the `X-Hub-Signature` HMAC, dedupes, and async-invokes the processor, which resolves the tenant, looks up the project→repo mapping, enriches the task with the issue's recent comments and screened file attachments (see [Issue context](#issue-context-attachments-and-comments)), and creates a task. Jira-triggered tasks always run the `coding/new-task-v1` workflow (the processor pins `workflow_ref` explicitly, since a label-triggered task always targets a mapped repo). The agent clones the repo, opens a PR, and posts a "started" comment on the Jira issue via the Jira REST v3 API (using the same stored OAuth token). When the task reaches a terminal state, the platform's fan-out plane posts a single final status comment — outcome, cost, turns, duration, and PR link — via the same REST v3 endpoint (see [How it works](#how-it-works) below).
+A Jira-site admin creates an Atlassian OAuth 2.0 (3LO) app and authorizes it on the site. The OAuth token bundle is stored in a per-tenant Secrets Manager secret (`bgagent-jira-oauth-<cloudId>`). When a user adds the trigger label to a Jira issue, Jira fires a webhook to ABCA; the receiver verifies the `X-Hub-Signature` HMAC, dedupes, and async-invokes the processor, which resolves the tenant, looks up the project→repo mapping, enriches the task with the issue's recent comments and screened file attachments (see [Issue context](#issue-context-attachments-and-comments)), and creates a task. Jira-triggered tasks always run the `coding/new-task-v1` workflow (the processor pins `workflow_ref` explicitly, since a label-triggered task always targets a mapped repo). A later `@bgagent` comment resolves that Jira issue to its most recent ABCA pull request and runs `coding/pr-iteration-v1` against the same PR. The agent clones the repo, opens or updates the PR, and posts a "started" comment on the Jira issue via the Jira REST v3 API (using the same stored OAuth token). When the task reaches a terminal state, the platform's fan-out plane posts a single final status comment — outcome, cost, turns, duration, and PR link — via the same REST v3 endpoint (see [How it works](#how-it-works) below).
 
 **Tenant key.** Everything is indexed on `cloudId` — the Atlassian tenant UUID, *not* the site domain or name. Webhook payloads and the OAuth flow both surface `cloudId`; it is the join key across the project-mapping, user-mapping, and workspace-registry tables.
 
@@ -135,7 +135,7 @@ This runs the OAuth 3LO dance:
 `setup` then prompts for a **webhook signing secret**. Unlike Linear, Atlassian does **not** auto-generate one — the operator chooses it at webhook-create time. In a second terminal, open **Jira → Settings → System → Webhooks → Create a Webhook** and enter:
 
 - **URL** — the `…/jira/webhook` URL that `setup` prints
-- **Events** — *Issue: created* and *Issue: updated*
+- **Events** — *Issue: created*, *Issue: updated*, and *Comment: created*
 - **Secret** — a strong random value, e.g. `openssl rand -hex 32`
 
 Paste that same secret value back at the `Webhook signing secret:` prompt. ABCA stores it on the per-tenant OAuth bundle (and mirrors it stack-wide), and the receiver looks it up to verify `X-Hub-Signature` on each delivery.
@@ -184,6 +184,8 @@ The teammate needs their own ABCA account first (Cognito user + configured CLI).
 
 Add the trigger label (`bgagent` by default) to a Jira issue in a mapped project. The agent should start within ~30 seconds, comment on the issue as it works, and post a PR link when ready. The issue **summary** plus the **description** (converted from Atlassian Document Format to markdown), the issue's **recent comments**, and any supported **file attachments** become the task context — see [Issue context: attachments and comments](#issue-context-attachments-and-comments).
 
+After the PR exists, add a Jira comment such as `@bgagent update the README too`. ABCA should acknowledge the request on the issue and update the existing PR.
+
 ## How webhook signature verification works
 
 Atlassian signs each delivery with HMAC-SHA256 over the **raw request body**, delivered as `X-Hub-Signature: sha256=<hex>`. The receiver:
@@ -198,8 +200,19 @@ The body must be verified as the *raw unparsed bytes* — never parsed-and-restr
 
 - **`jira:issue_created`** — triggers if the trigger label is already present on the new issue.
 - **`jira:issue_updated`** — triggers only if the label was **newly added** in this update. Jira reports label changes in `changelog.items[]` (`field: "labels"`, with `fromString` / `toString`), *not* by re-sending the full label list. The processor diffs the changelog rather than inspecting `issue.fields.labels`, so re-saving an issue that already has the label does not re-trigger.
+- **`comment_created`** — triggers only when the new comment contains a token-bounded `@bgagent` mention and the issue has a prior ABCA pull request.
 - All other event types get a silent `200`.
 
+## Comment-triggered PR iteration
+
+A `comment_created` webhook starts a PR iteration only when the comment contains the token-bounded mention `@bgagent` (case-insensitive). The remaining comment text becomes the `coding/pr-iteration-v1` instruction. A bare `@bgagent` asks the agent to address the latest PR review feedback.
+
+ABCA resolves the Jira tenant and issue key to the newest prior task that actually opened a PR. Newer attempts without a PR do not hide an older valid PR target. If no ABCA PR exists, ABCA posts a clear comment and creates no task.
+
+When the comment author has linked their Jira and ABCA accounts, the iteration is attributed to that user. Otherwise, ABCA falls back to the original task owner so a useful reviewer request is not dropped. Comments without the mention, app-authored comments, and ABCA's own generated status comments are no-ops.
+
+The acknowledgement is immediate after task admission. The existing platform fan-out path posts the terminal outcome and cost comment when the iteration finishes. Comment redelivery is idempotent: the webhook receiver deduplicates by Jira comment ID, and task creation uses a deterministic idempotency key as a second guard.
+
 ## Issue context: attachments and comments
 
 Beyond the summary and description, the processor enriches the task with the practical context a Jira ticket usually carries — attached files and recent clarifications — so the agent isn't left guessing at "see the attached log" or an acceptance detail buried in a comment. Both are fetched **authenticated at task-admission time** using the tenant's existing `read:jira-work` scope (**no new OAuth scopes, no re-authorization**), because a headless agent can't fetch them itself.
@@ -246,11 +259,12 @@ The feature targets Jira **statuses**, not board columns. Because moving a card
 
 ## Webhook dedup
 
-The receiver dedupes on `{issueKey}#{webhookEventTimestamp}` with an 8-hour TTL. Using the event timestamp (rather than event type) means two distinct label-adds in quick succession are not collapsed. Jira retries far less aggressively than Linear, so 8 hours is safe parity.
+The receiver dedupes issue events on `{issueKey}#{webhookEvent}#{timestamp}` and comment-created events on `{issueKey}#comment_created#{commentId}`, with an 8-hour TTL. The timestamp keeps distinct label additions separate; the stable comment ID collapses redelivery without merging separate comments. Jira retries far less aggressively than Linear, so 8 hours is safe parity.
 
 ## Usage
 
 - **Trigger a task**: add the trigger label to an issue in a mapped Jira project.
+- **Iterate on its PR**: comment `@bgagent <change>` on the Jira issue after ABCA has opened a PR.
 - **Check status**: from the Jira issue (progress comments) or `bgagent list` / `bgagent status <task-id>`.
 - **Cancel**: `bgagent cancel <task-id>`. Removing the Jira label does not cancel a running task.