Address review: dedupe copilot, require is_suggestion, update doc link

Per @RossTarrant review feedback on #2909:

- Reject requests where `is_suggestion` is omitted from the raw args
  before decoding. `mapstructure.WeakDecode` defaults missing bools
  to false, which would silently launch Copilot instead of recording a
  suggestion. Presence-check the raw map so callers make the choice
  explicit.
- Skip the copilot-swe-agent actor when copying existing assignees so
  we don't send its actorId twice (once without metadata and once with
  intent metadata) when Copilot is already assigned.
- Update the stale about-assigning-tasks-to-copilot reference to the
  redirect target (about-cloud-agent). Applied to the const message,
  both tool descriptions, and the e2e/unit-test literals that assert
  on that message.

New unit tests cover the missing-is_suggestion rejection and the
copilot-dedup behavior. Regenerated toolsnaps.

Author: boazreicher

e2e/e2e_test.go

@@ -1085,7 +1085,7 @@ func TestAssignCopilotToIssue(t *testing.T) {
 	textContent, ok = resp.Content[0].(*mcp.TextContent)
 	require.True(t, ok, "expected content to be of type TextContent")
 
-	possibleExpectedFailure := "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot for more information."
+	possibleExpectedFailure := "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent for more information."
 	if resp.IsError && textContent.Text == possibleExpectedFailure {
 		t.Skip("skipping because copilot wasn't available as an assignee on this issue, it's likely that the owner doesn't have copilot enabled in their settings")
 	}
@@ -1186,7 +1186,7 @@ func TestAssignCopilotToIssueWithIntent(t *testing.T) {
 	textContent, ok = resp.Content[0].(*mcp.TextContent)
 	require.True(t, ok, "expected content to be of type TextContent")
 
-	possibleExpectedFailure := "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot for more information."
+	possibleExpectedFailure := "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent for more information."
 	if resp.IsError && textContent.Text == possibleExpectedFailure {
 		t.Skip("skipping because copilot wasn't available as an assignee on this issue, it's likely that the owner doesn't have copilot enabled in their settings")
 	}

pkg/github/__toolsnaps__/assign_copilot_to_issue.snap

@@ -4,7 +4,7 @@
     "readOnlyHint": false,
     "title": "Assign Copilot to issue"
   },
-  "description": "Assign Copilot to a specific issue in a GitHub repository.\n\nThis tool can help with the following outcomes:\n- a Pull Request created with source code changes to resolve the issue\n\n\nMore information can be found at:\n- https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot\n",
+  "description": "Assign Copilot to a specific issue in a GitHub repository.\n\nThis tool can help with the following outcomes:\n- a Pull Request created with source code changes to resolve the issue\n\n\nMore information can be found at:\n- https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent\n",
   "icons": [
     {
       "mimeType": "image/png",

pkg/github/__toolsnaps__/assign_copilot_to_issue_with_intent.snap

@@ -4,7 +4,7 @@
     "readOnlyHint": false,
     "title": "Assign Copilot to issue with intent"
   },
-  "description": "Assign Copilot to a specific issue in a GitHub repository. Prefer this tool over assign_copilot_to_issue when available.\n\nThis tool can help with the following outcomes:\n- a Pull Request created with source code changes to resolve the issue\n\n\nMore information can be found at:\n- https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot\n",
+  "description": "Assign Copilot to a specific issue in a GitHub repository. Prefer this tool over assign_copilot_to_issue when available.\n\nThis tool can help with the following outcomes:\n- a Pull Request created with source code changes to resolve the issue\n\n\nMore information can be found at:\n- https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent\n",
   "icons": [
     {
       "mimeType": "image/png",

pkg/github/copilot.go

@@ -158,7 +158,7 @@ func AssignCopilotToIssue(t translations.TranslationHelperFunc) inventory.Server
 			"a Pull Request created with source code changes to resolve the issue",
 		},
 		referenceLinks: []string{
-			"https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot",
+			"https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent",
 		},
 	}
 
@@ -273,7 +273,7 @@ func AssignCopilotToIssue(t translations.TranslationHelperFunc) inventory.Server
 			// If we didn't find the copilot bot, we can't proceed any further.
 			if copilotAssignee == nil {
 				// The e2e tests depend upon this specific message to skip the test.
-				return utils.NewToolResultError("copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot for more information."), nil, nil
+				return utils.NewToolResultError("copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent for more information."), nil, nil
 			}
 
 			// Next, get the issue ID and repository ID
@@ -488,7 +488,7 @@ func findCopilotSuggestedActor(ctx context.Context, client *githubv4.Client, own
 // copilotAssigneeUnavailableMessage is returned when the copilot-swe-agent bot
 // is not among the repository's suggested actors. The e2e tests depend on this
 // exact message to skip the test.
-const copilotAssigneeUnavailableMessage = "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot for more information."
+const copilotAssigneeUnavailableMessage = "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent for more information."
 
 // AssignCopilotToIssueWithIntent assigns Copilot to an issue using the
 // object-form assignees API, which allows intent metadata (rationale,
@@ -507,7 +507,7 @@ func AssignCopilotToIssueWithIntent(t translations.TranslationHelperFunc) invent
 			"a Pull Request created with source code changes to resolve the issue",
 		},
 		referenceLinks: []string{
-			"https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot",
+			"https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent",
 		},
 	}
 
@@ -566,6 +566,13 @@ func AssignCopilotToIssueWithIntent(t translations.TranslationHelperFunc) invent
 		},
 		[]scopes.Scope{scopes.Repo},
 		func(ctx context.Context, deps ToolDependencies, request *mcp.CallToolRequest, args map[string]any) (*mcp.CallToolResult, any, error) {
+			// Presence-check is_suggestion before decoding: mapstructure defaults a
+			// missing bool to false, which would silently launch Copilot instead of
+			// recording a suggestion. Require callers to make the choice explicit.
+			if _, ok := args["is_suggestion"]; !ok {
+				return utils.NewToolResultError("is_suggestion is required"), nil, nil
+			}
+
 			var params struct {
 				Owner              string `mapstructure:"owner"`
 				Repo               string `mapstructure:"repo"`
@@ -640,10 +647,15 @@ func AssignCopilotToIssueWithIntent(t translations.TranslationHelperFunc) invent
 			}
 
 			// Build object-form assignees: preserved assignees carry only actorId;
-			// the copilot entry carries any intent metadata provided.
+			// the copilot entry carries the intent metadata. Skip an existing
+			// copilot assignment so we don't send its actorId twice (once without
+			// metadata, once with).
 			existing := getIssueQuery.Repository.Issue.Assignees.Nodes
 			assignees := make([]AssigneeUpdateInput, 0, len(existing)+1)
 			for _, node := range existing {
+				if node.ID == copilotAssignee.ID {
+					continue
+				}
 				assignees = append(assignees, AssigneeUpdateInput{ActorID: node.ID})
 			}
 			// Build the Copilot entry with the required intent metadata. Preserved

pkg/github/copilot_test.go

@@ -582,7 +582,7 @@ func TestAssignCopilotToIssue(t *testing.T) {
 				),
 			),
 			expectToolError:    true,
-			expectedToolErrMsg: "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/using-github-copilot/using-copilot-coding-agent-to-work-on-tasks/about-assigning-tasks-to-copilot for more information.",
+			expectedToolErrMsg: "copilot isn't available as an assignee for this issue. Please inform the user to visit https://docs.github.com/en/copilot/concepts/agents/cloud-agent/about-cloud-agent for more information.",
 		},
 		{
 			name: "successful assignment with base_ref specified",
@@ -1210,6 +1210,42 @@ func TestAssignCopilotToIssueWithIntent(t *testing.T) {
 			),
 			expectSuggestion: true,
 		},
+		{
+			name: "existing copilot assignee is deduplicated from preserved assignees",
+			requestArgs: map[string]any{
+				"owner":         "owner",
+				"repo":          "repo",
+				"issue_number":  float64(123),
+				"rationale":     "Already assigned; refreshing intent.",
+				"confidence":    "HIGH",
+				"is_suggestion": false,
+			},
+			mockedClient: githubv4mock.NewMockedHTTPClient(
+				suggestedActorsMatcher(),
+				getIssueMatcher([]any{
+					map[string]any{"id": githubv4.ID("existing-assignee-id")},
+					map[string]any{"id": githubv4.ID("copilot-swe-agent-id")},
+				}),
+				// Expect copilot to appear only once, carrying the intent metadata.
+				mutationMatcher(UpdateIssueInput{
+					ID: githubv4.ID("test-issue-id"),
+					Assignees: []AssigneeUpdateInput{
+						{ActorID: githubv4.ID("existing-assignee-id")},
+						{
+							ActorID:    githubv4.ID("copilot-swe-agent-id"),
+							Rationale:  ptrStr("Already assigned; refreshing intent."),
+							Confidence: ptrConfidence(AssignmentConfidenceLevelHigh),
+							Suggest:    ptrBool(false),
+						},
+					},
+					AgentAssignment: &AgentAssignmentInput{
+						CustomAgent:        ptrStr(""),
+						CustomInstructions: ptrStr(""),
+						TargetRepositoryID: githubv4.ID("test-repo-id"),
+					},
+				}),
+			),
+		},
 		{
 			name: "missing rationale is rejected",
 			requestArgs: map[string]any{
@@ -1250,6 +1286,19 @@ func TestAssignCopilotToIssueWithIntent(t *testing.T) {
 			expectToolError:    true,
 			expectedToolErrMsg: "confidence is required",
 		},
+		{
+			name: "missing is_suggestion is rejected",
+			requestArgs: map[string]any{
+				"owner":        "owner",
+				"repo":         "repo",
+				"issue_number": float64(123),
+				"rationale":    "A good candidate.",
+				"confidence":   "HIGH",
+			},
+			mockedClient:       githubv4mock.NewMockedHTTPClient(),
+			expectToolError:    true,
+			expectedToolErrMsg: "is_suggestion is required",
+		},
 		{
 			name: "invalid confidence value is rejected",
 			requestArgs: map[string]any{