diff --git a/internal/jirapoll/poller.go b/internal/jirapoll/poller.go
index b10426a36b..ecf39e0c3e 100644
--- a/internal/jirapoll/poller.go
+++ b/internal/jirapoll/poller.go
@@ -107,6 +107,18 @@ func (p *Poller) Run(ctx context.Context) error {
 	p.roleGroups = make(map[string][]string)
 	p.roleGroupsChecked = make(map[string]bool)
 
+	// Auth preflight: verify credentials before any discovery, lock, or
+	// checkpoint operations. Without this, bad credentials cause Jira to
+	// treat the request as unauthenticated and return empty results —
+	// indistinguishable from a genuinely quiet project.
+	myself, err := p.client.GetMyself(ctx)
+	if err != nil {
+		return fmt.Errorf("authentication preflight failed: %w", err)
+	}
+	if !myself.Active {
+		return fmt.Errorf("authentication preflight failed: account %q is inactive", myself.AccountID)
+	}
+
 	// Step 1: Execute JQL to get candidate issues.
 	candidates, err := p.searchCandidates(ctx)
 	if err != nil {
diff --git a/internal/jirapoll/poller_test.go b/internal/jirapoll/poller_test.go
index 13589600d4..d91ccc5174 100644
--- a/internal/jirapoll/poller_test.go
+++ b/internal/jirapoll/poller_test.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -80,6 +81,7 @@ func newMockClient() *mockClient {
 		propertySetErr: make(map[string]error),
 		statuses:       make(map[string]jira.Status),
 		statusErr:      make(map[string]error),
+		myselfUser:     &jira.User{AccountID: "poller-service-account", AccountType: "atlassian", Active: true},
 	}
 }
 
@@ -296,6 +298,97 @@ func TestRunEmptyPoll(t *testing.T) {
 	}
 }
 
+// TestRun_AuthPreflightFailure verifies that Run returns a clear
+// authentication error when GetMyself fails (e.g. 401/403), and that no
+// JQL discovery is attempted — preventing the silent-zero-candidates
+// failure mode described in #6831.
+func TestRun_AuthPreflightFailure(t *testing.T) {
+	mc := newMockClient()
+	mc.myselfErr = fmt.Errorf("jira api: 401 unauthorized")
+
+	dir := t.TempDir()
+	outputPath := filepath.Join(dir, "dispatches.json")
+
+	p := newTestPoller(mc, nil, Options{
+		TargetRepo:  "acme/platform",
+		JiraBaseURL: "https://acme.atlassian.net",
+		JiraProject: "PROJ",
+		OutputPath:  outputPath,
+	})
+
+	err := p.Run(context.Background())
+	if err == nil {
+		t.Fatal("expected Run() to return an error when authentication preflight fails")
+	}
+	if got := err.Error(); !strings.Contains(got, "authentication preflight") {
+		t.Errorf("error = %q, want it to mention authentication preflight", got)
+	}
+	// SearchIssues must not have been called — the preflight short-circuits.
+	if mc.lastQuery != "" {
+		t.Errorf("SearchIssues was called with JQL %q; expected no JQL discovery after auth failure", mc.lastQuery)
+	}
+	// The error must not expose credential material (the mock error is a
+	// status-code string, so this validates the wrapping does not inject
+	// secrets).
+	if strings.Contains(err.Error(), "token") || strings.Contains(err.Error(), "password") {
+		t.Errorf("error exposes credential material: %q", err.Error())
+	}
+}
+
+// TestRun_AuthPreflightInactiveAccount verifies that an inactive Jira
+// account is treated as an authentication failure.
+func TestRun_AuthPreflightInactiveAccount(t *testing.T) {
+	mc := newMockClient()
+	mc.myselfUser = &jira.User{
+		AccountID:   "deactivated-service-account",
+		AccountType: "atlassian",
+		Active:      false,
+	}
+
+	p := newTestPoller(mc, nil, Options{
+		TargetRepo:  "acme/platform",
+		JiraBaseURL: "https://acme.atlassian.net",
+		JiraProject: "PROJ",
+	})
+
+	err := p.Run(context.Background())
+	if err == nil {
+		t.Fatal("expected Run() to return an error for an inactive account")
+	}
+	if got := err.Error(); !strings.Contains(got, "inactive") {
+		t.Errorf("error = %q, want it to mention 'inactive'", got)
+	}
+	if mc.lastQuery != "" {
+		t.Errorf("SearchIssues was called; expected no JQL discovery after inactive-account check")
+	}
+}
+
+// TestRun_AuthPreflightSuccess verifies that a valid, active account
+// proceeds to JQL discovery as normal.
+func TestRun_AuthPreflightSuccess(t *testing.T) {
+	mc := newMockClient()
+	// myselfUser is already set to an active user by newMockClient.
+
+	dir := t.TempDir()
+	outputPath := filepath.Join(dir, "dispatches.json")
+
+	p := newTestPoller(mc, nil, Options{
+		TargetRepo:  "acme/platform",
+		JiraBaseURL: "https://acme.atlassian.net",
+		JiraProject: "PROJ",
+		OutputPath:  outputPath,
+	})
+
+	err := p.Run(context.Background())
+	if err != nil {
+		t.Fatalf("Run() error: %v", err)
+	}
+	// Verify SearchIssues was called — preflight passed and discovery ran.
+	if mc.lastQuery == "" {
+		t.Error("SearchIssues was not called; expected JQL discovery after successful auth preflight")
+	}
+}
+
 func TestRunHappyPath_CommentWithSlashCommand(t *testing.T) {
 	now := time.Now().Truncate(time.Second)
 	mc := newMockClient()