diff --git a/.github/workflows/campaign-generator.lock.yml b/.github/workflows/campaign-generator.lock.yml
index 18c715669bf..2904dbe0c88 100644
--- a/.github/workflows/campaign-generator.lock.yml
+++ b/.github/workflows/campaign-generator.lock.yml
@@ -230,25 +230,41 @@ jobs:
               "name": "add_comment"
             },
             {
-              "description": "Assign the GitHub Copilot coding agent to work on an issue. The agent will analyze the issue and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot.",
+              "description": "Assign the GitHub Copilot coding agent to work on an issue or pull request. The agent will analyze the issue/PR and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. Example usage: assign_to_agent(issue_number=123, agent=\"copilot\") or assign_to_agent(pull_number=456, agent=\"copilot\")",
               "inputSchema": {
                 "additionalProperties": false,
+                "oneOf": [
+                  {
+                    "required": [
+                      "issue_number"
+                    ]
+                  },
+                  {
+                    "required": [
+                      "pull_number"
+                    ]
+                  }
+                ],
                 "properties": {
                   "agent": {
                     "description": "Agent identifier to assign. Defaults to 'copilot' (the Copilot coding agent) if not specified.",
                     "type": "string"
                   },
                   "issue_number": {
-                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements.",
+                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements. Either issue_number or pull_number must be provided, but not both.",
+                    "type": [
+                      "number",
+                      "string"
+                    ]
+                  },
+                  "pull_number": {
+                    "description": "Pull request number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 456 in github.com/owner/repo/pull/456). Either issue_number or pull_number must be provided, but not both.",
                     "type": [
                       "number",
                       "string"
                     ]
                   }
                 },
-                "required": [
-                  "issue_number"
-                ],
                 "type": "object"
               },
               "name": "assign_to_agent"
diff --git a/.github/workflows/discussion-task-mining.campaign.lock.yml b/.github/workflows/discussion-task-mining.campaign.lock.yml
index 1fd4548b6a9..0067b4519d7 100644
--- a/.github/workflows/discussion-task-mining.campaign.lock.yml
+++ b/.github/workflows/discussion-task-mining.campaign.lock.yml
@@ -1103,7 +1103,7 @@ jobs:
           
           | Field | Type | Allowed / Notes |
           |---|---|---|
-          | `status` | single-select | `Todo` / `In Progress` / `Done` |
+          | `status` | single-select | `Todo` / `In Progress` / `Review required` / `Blocked` / `Done` |
           | `campaign_id` | text | Must equal `discussion-task-mining` |
           | `worker_workflow` | text | workflow ID or `"unknown"` |
           | `repository` | text | `owner/repo` |
diff --git a/.github/workflows/docs-quality-maintenance-project67.campaign.lock.yml b/.github/workflows/docs-quality-maintenance-project67.campaign.lock.yml
index 98e98f2fad9..c6bdeeb8f7f 100644
--- a/.github/workflows/docs-quality-maintenance-project67.campaign.lock.yml
+++ b/.github/workflows/docs-quality-maintenance-project67.campaign.lock.yml
@@ -1113,7 +1113,7 @@ jobs:
           
           | Field | Type | Allowed / Notes |
           |---|---|---|
-          | `status` | single-select | `Todo` / `In Progress` / `Done` |
+          | `status` | single-select | `Todo` / `In Progress` / `Review required` / `Blocked` / `Done` |
           | `campaign_id` | text | Must equal `docs-quality-maintenance-project73` |
           | `worker_workflow` | text | workflow ID or `"unknown"` |
           | `repository` | text | `owner/repo` |
diff --git a/.github/workflows/file-size-reduction-project71.campaign.lock.yml b/.github/workflows/file-size-reduction-project71.campaign.lock.yml
index 8075e6e0d7b..34ee1b1aa56 100644
--- a/.github/workflows/file-size-reduction-project71.campaign.lock.yml
+++ b/.github/workflows/file-size-reduction-project71.campaign.lock.yml
@@ -1110,7 +1110,7 @@ jobs:
           
           | Field | Type | Allowed / Notes |
           |---|---|---|
-          | `status` | single-select | `Todo` / `In Progress` / `Done` |
+          | `status` | single-select | `Todo` / `In Progress` / `Review required` / `Blocked` / `Done` |
           | `campaign_id` | text | Must equal `file-size-reduction-project71` |
           | `worker_workflow` | text | workflow ID or `"unknown"` |
           | `repository` | text | `owner/repo` |
diff --git a/.github/workflows/issue-monster.lock.yml b/.github/workflows/issue-monster.lock.yml
index 6dc57f2e540..76585071d78 100644
--- a/.github/workflows/issue-monster.lock.yml
+++ b/.github/workflows/issue-monster.lock.yml
@@ -209,25 +209,41 @@ jobs:
               "name": "add_comment"
             },
             {
-              "description": "Assign the GitHub Copilot coding agent to work on an issue. The agent will analyze the issue and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. CONSTRAINTS: Maximum 3 issue(s) can be assigned to agent.",
+              "description": "Assign the GitHub Copilot coding agent to work on an issue or pull request. The agent will analyze the issue/PR and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. Example usage: assign_to_agent(issue_number=123, agent=\"copilot\") or assign_to_agent(pull_number=456, agent=\"copilot\") CONSTRAINTS: Maximum 3 issue(s) can be assigned to agent.",
               "inputSchema": {
                 "additionalProperties": false,
+                "oneOf": [
+                  {
+                    "required": [
+                      "issue_number"
+                    ]
+                  },
+                  {
+                    "required": [
+                      "pull_number"
+                    ]
+                  }
+                ],
                 "properties": {
                   "agent": {
                     "description": "Agent identifier to assign. Defaults to 'copilot' (the Copilot coding agent) if not specified.",
                     "type": "string"
                   },
                   "issue_number": {
-                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements.",
+                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements. Either issue_number or pull_number must be provided, but not both.",
+                    "type": [
+                      "number",
+                      "string"
+                    ]
+                  },
+                  "pull_number": {
+                    "description": "Pull request number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 456 in github.com/owner/repo/pull/456). Either issue_number or pull_number must be provided, but not both.",
                     "type": [
                       "number",
                       "string"
                     ]
                   }
                 },
-                "required": [
-                  "issue_number"
-                ],
                 "type": "object"
               },
               "name": "assign_to_agent"
diff --git a/.github/workflows/playground-assign-to-agent.lock.yml b/.github/workflows/playground-assign-to-agent.lock.yml
index 46bd4268106..6883c9f9c02 100644
--- a/.github/workflows/playground-assign-to-agent.lock.yml
+++ b/.github/workflows/playground-assign-to-agent.lock.yml
@@ -25,8 +25,8 @@ name: "Playground: assign-to-agent"
 "on":
   workflow_dispatch:
     inputs:
-      issue_url:
-        description: Issue URL to assign agent to (e.g., https://github.com/owner/repo/issues/123)
+      item_url:
+        description: Issue or PR URL to assign agent to (e.g., https://github.com/owner/repo/issues/123 or https://github.com/owner/repo/pull/456)
         required: true
         type: string
 
@@ -178,25 +178,41 @@ jobs:
           cat > /opt/gh-aw/safeoutputs/tools.json << 'EOF'
           [
             {
-              "description": "Assign the GitHub Copilot coding agent to work on an issue. The agent will analyze the issue and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. CONSTRAINTS: Maximum 1 issue(s) can be assigned to agent.",
+              "description": "Assign the GitHub Copilot coding agent to work on an issue or pull request. The agent will analyze the issue/PR and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. Example usage: assign_to_agent(issue_number=123, agent=\"copilot\") or assign_to_agent(pull_number=456, agent=\"copilot\") CONSTRAINTS: Maximum 1 issue(s) can be assigned to agent.",
               "inputSchema": {
                 "additionalProperties": false,
+                "oneOf": [
+                  {
+                    "required": [
+                      "issue_number"
+                    ]
+                  },
+                  {
+                    "required": [
+                      "pull_number"
+                    ]
+                  }
+                ],
                 "properties": {
                   "agent": {
                     "description": "Agent identifier to assign. Defaults to 'copilot' (the Copilot coding agent) if not specified.",
                     "type": "string"
                   },
                   "issue_number": {
-                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements.",
+                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements. Either issue_number or pull_number must be provided, but not both.",
+                    "type": [
+                      "number",
+                      "string"
+                    ]
+                  },
+                  "pull_number": {
+                    "description": "Pull request number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 456 in github.com/owner/repo/pull/456). Either issue_number or pull_number must be provided, but not both.",
                     "type": [
                       "number",
                       "string"
                     ]
                   }
                 },
-                "required": [
-                  "issue_number"
-                ],
                 "type": "object"
               },
               "name": "assign_to_agent"
@@ -446,31 +462,33 @@ jobs:
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
           GH_AW_SAFE_OUTPUTS: ${{ env.GH_AW_SAFE_OUTPUTS }}
-          GH_AW_GITHUB_EVENT_INPUTS_ISSUE_URL: ${{ github.event.inputs.issue_url }}
+          GH_AW_GITHUB_EVENT_INPUTS_ITEM_URL: ${{ github.event.inputs.item_url }}
         run: |
           bash /opt/gh-aw/actions/create_prompt_first.sh
           cat << 'PROMPT_EOF' > "$GH_AW_PROMPT"
           # Assign Agent Test Workflow
           
-          Test the `assign-to-agent` safe output feature by assigning the Copilot agent to an issue.
+          Test the `assign-to-agent` safe output feature by assigning the Copilot agent to an issue or pull request.
           
           ## Task
           
-          You have been provided with an issue URL: __GH_AW_GITHUB_EVENT_INPUTS_ISSUE_URL__
+          You have been provided with a GitHub URL: __GH_AW_GITHUB_EVENT_INPUTS_ITEM_URL__
           
-          1. Parse the issue URL to extract the owner, repo, and issue number
-          2. Validate that the URL is an issue URL (not a pull request URL)
-          3. Use the `assign_to_agent` tool from the `safeoutputs` MCP server to assign the Copilot agent to the issue
-          4. Pass the numeric issue_number (extracted from the URL) to the `assign_to_agent` tool
+          1. Parse the URL to extract the owner, repo, and number
+          2. Determine if the URL is an issue URL (contains `/issues/`) or a pull request URL (contains `/pull/`)
+          3. Use the `assign_to_agent` tool from the `safeoutputs` MCP server to assign the Copilot agent
+          4. Pass the appropriate parameter to the tool:
+             - For issues: pass `issue_number` (the numeric ID extracted from the URL)
+             - For pull requests: pass `pull_number` (the numeric ID extracted from the URL)
           
-          **Important**: Do not use GitHub tools directly for assignment. Only use the `assign_to_agent` safe output tool.
+          **Important**: Do not use GitHub tools directly for assignment. Only use the `assign_to_agent` safe output tool with the correct parameter based on the URL type.
           
           PROMPT_EOF
       - name: Substitute placeholders
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
-          GH_AW_GITHUB_EVENT_INPUTS_ISSUE_URL: ${{ github.event.inputs.issue_url }}
+          GH_AW_GITHUB_EVENT_INPUTS_ITEM_URL: ${{ github.event.inputs.item_url }}
         with:
           script: |
             const substitutePlaceholders = require('/opt/gh-aw/actions/substitute_placeholders.cjs');
@@ -479,7 +497,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
-                GH_AW_GITHUB_EVENT_INPUTS_ISSUE_URL: process.env.GH_AW_GITHUB_EVENT_INPUTS_ISSUE_URL
+                GH_AW_GITHUB_EVENT_INPUTS_ITEM_URL: process.env.GH_AW_GITHUB_EVENT_INPUTS_ITEM_URL
               }
             });
       - name: Append XPIA security instructions to prompt
@@ -587,7 +605,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
-          GH_AW_GITHUB_EVENT_INPUTS_ISSUE_URL: ${{ github.event.inputs.issue_url }}
+          GH_AW_GITHUB_EVENT_INPUTS_ITEM_URL: ${{ github.event.inputs.item_url }}
         with:
           script: |
             const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
diff --git a/.github/workflows/playground-assign-to-agent.md b/.github/workflows/playground-assign-to-agent.md
index d6416a4795c..57b55d7ff4b 100644
--- a/.github/workflows/playground-assign-to-agent.md
+++ b/.github/workflows/playground-assign-to-agent.md
@@ -3,8 +3,8 @@ name: "Playground: assign-to-agent"
 on: 
   workflow_dispatch:
     inputs:
-      issue_url:
-        description: 'Issue URL to assign agent to (e.g., https://github.com/owner/repo/issues/123)'
+      item_url:
+        description: 'Issue or PR URL to assign agent to (e.g., https://github.com/owner/repo/issues/123 or https://github.com/owner/repo/pull/456)'
         required: true
         type: string
 description: Test assign-to-agent safe output feature
@@ -32,15 +32,17 @@ timeout-minutes: 5
 
 # Assign Agent Test Workflow
 
-Test the `assign-to-agent` safe output feature by assigning the Copilot agent to an issue.
+Test the `assign-to-agent` safe output feature by assigning the Copilot agent to an issue or pull request.
 
 ## Task
 
-You have been provided with an issue URL: ${{ github.event.inputs.issue_url }}
+You have been provided with a GitHub URL: ${{ github.event.inputs.item_url }}
 
-1. Parse the issue URL to extract the owner, repo, and issue number
-2. Validate that the URL is an issue URL (not a pull request URL)
-3. Use the `assign_to_agent` tool from the `safeoutputs` MCP server to assign the Copilot agent to the issue
-4. Pass the numeric issue_number (extracted from the URL) to the `assign_to_agent` tool
+1. Parse the URL to extract the owner, repo, and number
+2. Determine if the URL is an issue URL (contains `/issues/`) or a pull request URL (contains `/pull/`)
+3. Use the `assign_to_agent` tool from the `safeoutputs` MCP server to assign the Copilot agent
+4. Pass the appropriate parameter to the tool:
+   - For issues: pass `issue_number` (the numeric ID extracted from the URL)
+   - For pull requests: pass `pull_number` (the numeric ID extracted from the URL)
 
-**Important**: Do not use GitHub tools directly for assignment. Only use the `assign_to_agent` safe output tool.
+**Important**: Do not use GitHub tools directly for assignment. Only use the `assign_to_agent` safe output tool with the correct parameter based on the URL type.
diff --git a/.github/workflows/workflow-generator.lock.yml b/.github/workflows/workflow-generator.lock.yml
index e99ffce9521..b352d209c87 100644
--- a/.github/workflows/workflow-generator.lock.yml
+++ b/.github/workflows/workflow-generator.lock.yml
@@ -208,25 +208,41 @@ jobs:
           cat > /opt/gh-aw/safeoutputs/tools.json << 'EOF'
           [
             {
-              "description": "Assign the GitHub Copilot coding agent to work on an issue. The agent will analyze the issue and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot.",
+              "description": "Assign the GitHub Copilot coding agent to work on an issue or pull request. The agent will analyze the issue/PR and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. Example usage: assign_to_agent(issue_number=123, agent=\"copilot\") or assign_to_agent(pull_number=456, agent=\"copilot\")",
               "inputSchema": {
                 "additionalProperties": false,
+                "oneOf": [
+                  {
+                    "required": [
+                      "issue_number"
+                    ]
+                  },
+                  {
+                    "required": [
+                      "pull_number"
+                    ]
+                  }
+                ],
                 "properties": {
                   "agent": {
                     "description": "Agent identifier to assign. Defaults to 'copilot' (the Copilot coding agent) if not specified.",
                     "type": "string"
                   },
                   "issue_number": {
-                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements.",
+                    "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements. Either issue_number or pull_number must be provided, but not both.",
+                    "type": [
+                      "number",
+                      "string"
+                    ]
+                  },
+                  "pull_number": {
+                    "description": "Pull request number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 456 in github.com/owner/repo/pull/456). Either issue_number or pull_number must be provided, but not both.",
                     "type": [
                       "number",
                       "string"
                     ]
                   }
                 },
-                "required": [
-                  "issue_number"
-                ],
                 "type": "object"
               },
               "name": "assign_to_agent"
diff --git a/actions/setup/js/assign_agent_helpers.cjs b/actions/setup/js/assign_agent_helpers.cjs
index 23dd6d37181..bb4daeb4785 100644
--- a/actions/setup/js/assign_agent_helpers.cjs
+++ b/actions/setup/js/assign_agent_helpers.cjs
@@ -173,14 +173,60 @@ async function getIssueDetails(owner, repo, issueNumber) {
 }
 
 /**
- * Assign agent to issue using GraphQL replaceActorsForAssignable mutation
- * @param {string} issueId - GitHub issue ID
+ * Get pull request details (ID and current assignees) using GraphQL
+ * @param {string} owner - Repository owner
+ * @param {string} repo - Repository name
+ * @param {number} pullNumber - Pull request number
+ * @returns {Promise<{pullRequestId: string, currentAssignees: string[]}|null>}
+ */
+async function getPullRequestDetails(owner, repo, pullNumber) {
+  const query = `
+    query($owner: String!, $repo: String!, $pullNumber: Int!) {
+      repository(owner: $owner, name: $repo) {
+        pullRequest(number: $pullNumber) {
+          id
+          assignees(first: 100) {
+            nodes {
+              id
+            }
+          }
+        }
+      }
+    }
+  `;
+
+  try {
+    const response = await github.graphql(query, { owner, repo, pullNumber });
+    const pullRequest = response.repository.pullRequest;
+
+    if (!pullRequest || !pullRequest.id) {
+      core.error("Could not get pull request data");
+      return null;
+    }
+
+    const currentAssignees = pullRequest.assignees.nodes.map(assignee => assignee.id);
+
+    return {
+      pullRequestId: pullRequest.id,
+      currentAssignees,
+    };
+  } catch (error) {
+    const errorMessage = getErrorMessage(error);
+    core.error(`Failed to get pull request details: ${errorMessage}`);
+    // Re-throw the error to preserve the original error message for permission error detection
+    throw error;
+  }
+}
+
+/**
+ * Assign agent to issue or pull request using GraphQL replaceActorsForAssignable mutation
+ * @param {string} assignableId - GitHub issue or pull request ID
  * @param {string} agentId - Agent ID
  * @param {string[]} currentAssignees - List of current assignee IDs
  * @param {string} agentName - Agent name for error messages
  * @returns {Promise<boolean>} True if successful
  */
-async function assignAgentToIssue(issueId, agentId, currentAssignees, agentName) {
+async function assignAgentToIssue(assignableId, agentId, currentAssignees, agentName) {
   // Build actor IDs array - include agent and preserve other assignees
   const actorIds = [agentId, ...currentAssignees.filter(id => id !== agentId)];
 
@@ -198,9 +244,9 @@ async function assignAgentToIssue(issueId, agentId, currentAssignees, agentName)
   try {
     core.info("Using built-in github object for mutation");
 
-    core.debug(`GraphQL mutation with variables: assignableId=${issueId}, actorIds=${JSON.stringify(actorIds)}`);
+    core.debug(`GraphQL mutation with variables: assignableId=${assignableId}, actorIds=${JSON.stringify(actorIds)}`);
     const response = await github.graphql(mutation, {
-      assignableId: issueId,
+      assignableId: assignableId,
       actorIds,
     });
 
@@ -295,9 +341,9 @@ async function assignAgentToIssue(issueId, agentId, currentAssignees, agentName)
           }
         `;
         core.info("Using built-in github object for fallback mutation");
-        core.debug(`Fallback GraphQL mutation with variables: assignableId=${issueId}, assigneeIds=[${agentId}]`);
+        core.debug(`Fallback GraphQL mutation with variables: assignableId=${assignableId}, assigneeIds=[${agentId}]`);
         const fallbackResp = await github.graphql(fallbackMutation, {
-          assignableId: issueId,
+          assignableId: assignableId,
           assigneeIds: [agentId],
         });
         if (fallbackResp?.addAssigneesToAssignable) {
@@ -447,6 +493,7 @@ module.exports = {
   getAvailableAgentLogins,
   findAgent,
   getIssueDetails,
+  getPullRequestDetails,
   assignAgentToIssue,
   logPermissionError,
   generatePermissionErrorSummary,
diff --git a/actions/setup/js/assign_to_agent.cjs b/actions/setup/js/assign_to_agent.cjs
index b29a7f5f09b..6e90f184568 100644
--- a/actions/setup/js/assign_to_agent.cjs
+++ b/actions/setup/js/assign_to_agent.cjs
@@ -3,7 +3,7 @@
 
 const { loadAgentOutput } = require("./load_agent_output.cjs");
 const { generateStagedPreview } = require("./staged_preview.cjs");
-const { AGENT_LOGIN_NAMES, getAvailableAgentLogins, findAgent, getIssueDetails, assignAgentToIssue, generatePermissionErrorSummary } = require("./assign_agent_helpers.cjs");
+const { AGENT_LOGIN_NAMES, getAvailableAgentLogins, findAgent, getIssueDetails, getPullRequestDetails, assignAgentToIssue, generatePermissionErrorSummary } = require("./assign_agent_helpers.cjs");
 const { getErrorMessage } = require("./error_helpers.cjs");
 
 async function main() {
@@ -27,7 +27,12 @@ async function main() {
       description: "The following agent assignments would be made if staged mode was disabled:",
       items: assignItems,
       renderItem: item => {
-        let content = `**Issue:** #${item.issue_number}\n`;
+        let content = "";
+        if (item.issue_number) {
+          content += `**Issue:** #${item.issue_number}\n`;
+        } else if (item.pull_number) {
+          content += `**Pull Request:** #${item.pull_number}\n`;
+        }
         content += `**Agent:** ${item.agent || "copilot"}\n`;
         content += "\n";
         return content;
@@ -80,11 +85,27 @@ async function main() {
   // Process each agent assignment
   const results = [];
   for (const item of itemsToProcess) {
-    const issueNumber = typeof item.issue_number === "number" ? item.issue_number : parseInt(String(item.issue_number), 10);
+    // Determine if this is an issue or PR assignment
+    const issueNumber = item.issue_number ? (typeof item.issue_number === "number" ? item.issue_number : parseInt(String(item.issue_number), 10)) : null;
+    const pullNumber = item.pull_number ? (typeof item.pull_number === "number" ? item.pull_number : parseInt(String(item.pull_number), 10)) : null;
     const agentName = item.agent ?? defaultAgent;
 
-    if (isNaN(issueNumber) || issueNumber <= 0) {
-      core.error(`Invalid issue_number: ${item.issue_number}`);
+    // Validate that we have either issue_number or pull_number
+    if (!issueNumber && !pullNumber) {
+      core.error("Missing both issue_number and pull_number in assign_to_agent item");
+      continue;
+    }
+
+    if (issueNumber && pullNumber) {
+      core.error("Cannot specify both issue_number and pull_number in the same assign_to_agent item");
+      continue;
+    }
+
+    const number = issueNumber || pullNumber;
+    const type = issueNumber ? "issue" : "pull request";
+
+    if (isNaN(number) || number <= 0) {
+      core.error(`Invalid ${type} number: ${number}`);
       continue;
     }
 
@@ -93,6 +114,7 @@ async function main() {
       core.warning(`Agent "${agentName}" is not supported. Supported agents: ${Object.keys(AGENT_LOGIN_NAMES).join(", ")}`);
       results.push({
         issue_number: issueNumber,
+        pull_number: pullNumber,
         agent: agentName,
         success: false,
         error: `Unsupported agent: ${agentName}`,
@@ -100,7 +122,7 @@ async function main() {
       continue;
     }
 
-    // Assign the agent to the issue using GraphQL
+    // Assign the agent to the issue or PR using GraphQL
     try {
       // Find agent (use cache if available) - uses built-in github object authenticated via github-token
       let agentId = agentCache[agentName];
@@ -114,20 +136,35 @@ async function main() {
         core.info(`Found ${agentName} coding agent (ID: ${agentId})`);
       }
 
-      // Get issue details (ID and current assignees) via GraphQL
-      core.info("Getting issue details...");
-      const issueDetails = await getIssueDetails(targetOwner, targetRepo, issueNumber);
-      if (!issueDetails) {
-        throw new Error("Failed to get issue details");
+      // Get issue or PR details (ID and current assignees) via GraphQL
+      core.info(`Getting ${type} details...`);
+      let assignableId;
+      let currentAssignees;
+
+      if (issueNumber) {
+        const issueDetails = await getIssueDetails(targetOwner, targetRepo, issueNumber);
+        if (!issueDetails) {
+          throw new Error(`Failed to get issue details`);
+        }
+        assignableId = issueDetails.issueId;
+        currentAssignees = issueDetails.currentAssignees;
+      } else {
+        const prDetails = await getPullRequestDetails(targetOwner, targetRepo, pullNumber);
+        if (!prDetails) {
+          throw new Error(`Failed to get pull request details`);
+        }
+        assignableId = prDetails.pullRequestId;
+        currentAssignees = prDetails.currentAssignees;
       }
 
-      core.info(`Issue ID: ${issueDetails.issueId}`);
+      core.info(`${type} ID: ${assignableId}`);
 
       // Check if agent is already assigned
-      if (issueDetails.currentAssignees.includes(agentId)) {
-        core.info(`${agentName} is already assigned to issue #${issueNumber}`);
+      if (currentAssignees.includes(agentId)) {
+        core.info(`${agentName} is already assigned to ${type} #${number}`);
         results.push({
           issue_number: issueNumber,
+          pull_number: pullNumber,
           agent: agentName,
           success: true,
         });
@@ -135,16 +172,17 @@ async function main() {
       }
 
       // Assign agent using GraphQL mutation - uses built-in github object authenticated via github-token
-      core.info(`Assigning ${agentName} coding agent to issue #${issueNumber}...`);
-      const success = await assignAgentToIssue(issueDetails.issueId, agentId, issueDetails.currentAssignees, agentName);
+      core.info(`Assigning ${agentName} coding agent to ${type} #${number}...`);
+      const success = await assignAgentToIssue(assignableId, agentId, currentAssignees, agentName);
 
       if (!success) {
         throw new Error(`Failed to assign ${agentName} via GraphQL`);
       }
 
-      core.info(`Successfully assigned ${agentName} coding agent to issue #${issueNumber}`);
+      core.info(`Successfully assigned ${agentName} coding agent to ${type} #${number}`);
       results.push({
         issue_number: issueNumber,
+        pull_number: pullNumber,
         agent: agentName,
         success: true,
       });
@@ -161,9 +199,10 @@ async function main() {
           core.debug("Failed to enrich unavailable agent message with available list");
         }
       }
-      core.error(`Failed to assign agent "${agentName}" to issue #${issueNumber}: ${errorMessage}`);
+      core.error(`Failed to assign agent "${agentName}" to ${type} #${number}: ${errorMessage}`);
       results.push({
         issue_number: issueNumber,
+        pull_number: pullNumber,
         agent: agentName,
         success: false,
         error: errorMessage,
@@ -181,7 +220,10 @@ async function main() {
     summaryContent += `✅ Successfully assigned ${successCount} agent(s):\n\n`;
     summaryContent += results
       .filter(r => r.success)
-      .map(r => `- Issue #${r.issue_number} → Agent: ${r.agent}`)
+      .map(r => {
+        const itemType = r.issue_number ? `Issue #${r.issue_number}` : `Pull Request #${r.pull_number}`;
+        return `- ${itemType} → Agent: ${r.agent}`;
+      })
       .join("\n");
     summaryContent += "\n\n";
   }
@@ -190,7 +232,10 @@ async function main() {
     summaryContent += `❌ Failed to assign ${failureCount} agent(s):\n\n`;
     summaryContent += results
       .filter(r => !r.success)
-      .map(r => `- Issue #${r.issue_number} → Agent: ${r.agent}: ${r.error}`)
+      .map(r => {
+        const itemType = r.issue_number ? `Issue #${r.issue_number}` : `Pull Request #${r.pull_number}`;
+        return `- ${itemType} → Agent: ${r.agent}: ${r.error}`;
+      })
       .join("\n");
 
     // Check if any failures were permission-related
@@ -206,7 +251,11 @@ async function main() {
   // Set outputs
   const assignedAgents = results
     .filter(r => r.success)
-    .map(r => `${r.issue_number}:${r.agent}`)
+    .map(r => {
+      const number = r.issue_number || r.pull_number;
+      const prefix = r.issue_number ? "issue" : "pr";
+      return `${prefix}:${number}:${r.agent}`;
+    })
     .join("\n");
   core.setOutput("assigned_agents", assignedAgents);
 
diff --git a/actions/setup/js/assign_to_agent.test.cjs b/actions/setup/js/assign_to_agent.test.cjs
index 39d986cd625..d37c628711b 100644
--- a/actions/setup/js/assign_to_agent.test.cjs
+++ b/actions/setup/js/assign_to_agent.test.cjs
@@ -227,7 +227,7 @@ describe("assign_to_agent", () => {
 
     await eval(`(async () => { ${assignToAgentScript}; await main(); })()`);
 
-    expect(mockCore.error).toHaveBeenCalledWith(expect.stringContaining("Invalid issue_number"));
+    expect(mockCore.error).toHaveBeenCalledWith(expect.stringContaining("Invalid issue number"));
   });
 
   it("should handle agent already assigned", async () => {
diff --git a/actions/setup/js/safe_outputs_tools.json b/actions/setup/js/safe_outputs_tools.json
index df900b4e211..be96b9081ad 100644
--- a/actions/setup/js/safe_outputs_tools.json
+++ b/actions/setup/js/safe_outputs_tools.json
@@ -337,21 +337,32 @@
   },
   {
     "name": "assign_to_agent",
-    "description": "Assign the GitHub Copilot coding agent to work on an issue. The agent will analyze the issue and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot.",
+    "description": "Assign the GitHub Copilot coding agent to work on an issue or pull request. The agent will analyze the issue/PR and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. Example usage: assign_to_agent(issue_number=123, agent=\"copilot\") or assign_to_agent(pull_number=456, agent=\"copilot\")",
     "inputSchema": {
       "type": "object",
-      "required": ["issue_number"],
       "properties": {
         "issue_number": {
           "type": ["number", "string"],
-          "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements."
+          "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements. Either issue_number or pull_number must be provided, but not both."
+        },
+        "pull_number": {
+          "type": ["number", "string"],
+          "description": "Pull request number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 456 in github.com/owner/repo/pull/456). Either issue_number or pull_number must be provided, but not both."
         },
         "agent": {
           "type": "string",
           "description": "Agent identifier to assign. Defaults to 'copilot' (the Copilot coding agent) if not specified."
         }
       },
-      "additionalProperties": false
+      "additionalProperties": false,
+      "oneOf": [
+        {
+          "required": ["issue_number"]
+        },
+        {
+          "required": ["pull_number"]
+        }
+      ]
     }
   },
   {
diff --git a/docs/src/content/docs/reference/safe-outputs.md b/docs/src/content/docs/reference/safe-outputs.md
index efc089c9e90..c4e7186b15d 100644
--- a/docs/src/content/docs/reference/safe-outputs.md
+++ b/docs/src/content/docs/reference/safe-outputs.md
@@ -49,7 +49,7 @@ The agent requests issue creation; a separate job with `issues: write` creates i
 - [**Add Labels**](#add-labels-add-labels) (`add-labels`) — Add labels to issues or PRs (max: 3)
 - [**Add Reviewer**](#add-reviewer-add-reviewer) (`add-reviewer`) — Add reviewers to pull requests (max: 3)
 - [**Assign Milestone**](#assign-milestone-assign-milestone) (`assign-milestone`) — Assign issues to milestones (max: 1)
-- [**Assign to Agent**](#assign-to-agent-assign-to-agent) (`assign-to-agent`) — Assign Copilot agents to issues (max: 1)
+- [**Assign to Agent**](#assign-to-agent-assign-to-agent) (`assign-to-agent`) — Assign Copilot agents to issues or PRs (max: 1)
 - [**Assign to User**](#assign-to-user-assign-to-user) (`assign-to-user`) — Assign users to issues (max: 1)
 
 ### Projects, Releases & Assets
@@ -746,13 +746,15 @@ Creates Copilot agent sessions. Requires `COPILOT_GITHUB_TOKEN` or `GH_AW_GITHUB
 
 ### Assign to Agent (`assign-to-agent:`)
 
-Assigns Copilot coding agent to issues. Requires fine-grained PAT with actions, contents, issues, pull requests write access stored as `GH_AW_AGENT_TOKEN`, or GitHub App token. Supported agents: `copilot` (`copilot-swe-agent`).
+Assigns Copilot coding agent to issues or pull requests. Requires fine-grained PAT with actions, contents, issues, pull requests write access stored as `GH_AW_AGENT_TOKEN`, or GitHub App token. Supported agents: `copilot` (`copilot-swe-agent`).
+
+The agent must provide either `issue_number` or `pull_number` in the output to specify which item to assign.
 
 ```yaml wrap
 safe-outputs:
   assign-to-agent:
-    name: "copilot"
-    target-repo: "owner/repo" # cross-repository
+    name: "copilot"            # default agent (optional)
+    target-repo: "owner/repo"  # cross-repository
 ```
 
 ### Assign to User (`assign-to-user:`)
diff --git a/pkg/workflow/js/safe_outputs_tools.json b/pkg/workflow/js/safe_outputs_tools.json
index bd0d42ee1ac..a5f69ccb01f 100644
--- a/pkg/workflow/js/safe_outputs_tools.json
+++ b/pkg/workflow/js/safe_outputs_tools.json
@@ -489,26 +489,42 @@
   },
   {
     "name": "assign_to_agent",
-    "description": "Assign the GitHub Copilot coding agent to work on an issue. The agent will analyze the issue and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot.",
+    "description": "Assign the GitHub Copilot coding agent to work on an issue or pull request. The agent will analyze the issue/PR and attempt to implement a solution, creating a pull request when complete. Use this to delegate coding tasks to Copilot. Example usage: assign_to_agent(issue_number=123, agent=\"copilot\") or assign_to_agent(pull_number=456, agent=\"copilot\")",
     "inputSchema": {
       "type": "object",
-      "required": [
-        "issue_number"
-      ],
       "properties": {
         "issue_number": {
           "type": [
             "number",
             "string"
           ],
-          "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements."
+          "description": "Issue number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 234 in github.com/owner/repo/issues/234). The issue should contain clear, actionable requirements. Either issue_number or pull_number must be provided, but not both."
+        },
+        "pull_number": {
+          "type": [
+            "number",
+            "string"
+          ],
+          "description": "Pull request number to assign the Copilot agent to. This is the numeric ID from the GitHub URL (e.g., 456 in github.com/owner/repo/pull/456). Either issue_number or pull_number must be provided, but not both."
         },
         "agent": {
           "type": "string",
           "description": "Agent identifier to assign. Defaults to 'copilot' (the Copilot coding agent) if not specified."
         }
       },
-      "additionalProperties": false
+      "additionalProperties": false,
+      "oneOf": [
+        {
+          "required": [
+            "issue_number"
+          ]
+        },
+        {
+          "required": [
+            "pull_number"
+          ]
+        }
+      ]
     }
   },
   {