diff --git a/CHANGELOG.md b/CHANGELOG.md
index d6aefde..e822945 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- Prevent global coverage reports from timing out on large archives by aggregating messages in one sequential scan and allowing a longer bounded deadline.
 - Preserve guild and member history with source-attributed tombstones, explicit restore semantics, omission-safe member refreshes, and revision-aware Git-share merges.
 - Keep attachment fetches compatible with three allowed Discord CDN redirects and injected HTTP transports while preserving final-response host validation.
 - Reject malformed tombstone timestamps before routine incremental snapshot imports mutate the archive.
diff --git a/internal/store/coverage.go b/internal/store/coverage.go
index 62b0431..e23171a 100644
--- a/internal/store/coverage.go
+++ b/internal/store/coverage.go
@@ -11,7 +11,50 @@ import (
 
 const wiretapStatsScope = "wiretap:last_stats:v1"
 
-const coverageQueryTimeout = 2 * time.Minute
+const (
+	coverageQueryTimeout       = 2 * time.Minute
+	globalCoverageQueryTimeout = 8 * time.Minute
+)
+
+const filteredCoverageChannelQuery = `
+	select
+		c.id, c.guild_id, c.name, c.kind,
+		case when exists (
+			select 1 from sync_state s
+			where s.scope = 'channel:' || c.id || ':history_complete'
+		) then 1 else 0 end,
+		count(m.id), coalesce(min(m.created_at), ''), coalesce(max(m.created_at), '')
+	from channels c
+	left join messages m on m.channel_id = c.id and m.deleted_at is null
+	where c.guild_id = ?
+	group by c.id, c.guild_id, c.name, c.kind
+	order by c.guild_id, count(m.id) desc, lower(c.name), c.id
+`
+
+const globalCoverageChannelQuery = `
+	with message_coverage as materialized (
+		select
+			channel_id,
+			count(*) as message_count,
+			coalesce(min(created_at), '') as earliest_message_at,
+			coalesce(max(created_at), '') as latest_message_at
+		from messages not indexed
+		where deleted_at is null
+		group by channel_id
+	)
+	select
+		c.id, c.guild_id, c.name, c.kind,
+		case when exists (
+			select 1 from sync_state s
+			where s.scope = 'channel:' || c.id || ':history_complete'
+		) then 1 else 0 end,
+		coalesce(m.message_count, 0),
+		coalesce(m.earliest_message_at, ''),
+		coalesce(m.latest_message_at, '')
+	from channels c
+	left join message_coverage m on m.channel_id = c.id
+	order by c.guild_id, coalesce(m.message_count, 0) desc, lower(c.name), c.id
+`
 
 var messageChannelKinds = map[string]struct{}{
 	"text": {}, "news": {}, "announcement": {}, "dm": {}, "group_dm": {},
@@ -102,7 +145,7 @@ func (s *Store) SetWiretapImportStats(ctx context.Context, stats WiretapImportSt
 
 func (s *Store) Coverage(ctx context.Context, guildID string, generatedAt time.Time) (CoverageReport, error) {
 	report := CoverageReport{GeneratedAt: generatedAt.UTC(), Guilds: []CoverageGuild{}}
-	queryCtx, cancel := context.WithTimeout(ctx, coverageQueryTimeout)
+	queryCtx, cancel := withCoverageQueryTimeout(ctx, guildID)
 	defer cancel()
 
 	rows, err := s.db.QueryContext(queryCtx, `
@@ -137,20 +180,13 @@ func (s *Store) Coverage(ctx context.Context, guildID string, generatedAt time.T
 	for i := range report.Guilds {
 		guilds[report.Guilds[i].ID] = &report.Guilds[i]
 	}
-	channelRows, err := s.db.QueryContext(queryCtx, `
-		select
-			c.id, c.guild_id, c.name, c.kind,
-			case when exists (
-				select 1 from sync_state s
-				where s.scope = 'channel:' || c.id || ':history_complete'
-			) then 1 else 0 end,
-			count(m.id), coalesce(min(m.created_at), ''), coalesce(max(m.created_at), '')
-		from channels c
-		left join messages m on m.channel_id = c.id and m.deleted_at is null
-		where ? = '' or c.guild_id = ?
-		group by c.id, c.guild_id, c.name, c.kind
-		order by c.guild_id, count(m.id) desc, lower(c.name), c.id
-	`, guildID, guildID)
+	channelQuery := filteredCoverageChannelQuery
+	channelArgs := []any{guildID}
+	if guildID == "" {
+		channelQuery = globalCoverageChannelQuery
+		channelArgs = nil
+	}
+	channelRows, err := s.db.QueryContext(queryCtx, channelQuery, channelArgs...)
 	if err != nil {
 		return CoverageReport{}, fmt.Errorf("query channel coverage: %w", err)
 	}
@@ -226,6 +262,14 @@ func (s *Store) Coverage(ctx context.Context, guildID string, generatedAt time.T
 	return report, nil
 }
 
+func withCoverageQueryTimeout(ctx context.Context, guildID string) (context.Context, context.CancelFunc) {
+	timeout := coverageQueryTimeout
+	if guildID == "" {
+		timeout = globalCoverageQueryTimeout
+	}
+	return context.WithTimeout(ctx, timeout)
+}
+
 func (s *Store) loadKnownFailureCoverage(ctx context.Context, guildID string, report *CoverageReport) error {
 	rows, err := s.db.QueryContext(ctx, `
 		select guild_id, channel_id, count(*)
diff --git a/internal/store/coverage_test.go b/internal/store/coverage_test.go
index 8af199c..0835225 100644
--- a/internal/store/coverage_test.go
+++ b/internal/store/coverage_test.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
@@ -21,14 +22,19 @@ func TestCoverageReportsGuildChannelAndWiretapState(t *testing.T) {
 	require.NoError(t, s.UpsertGuild(ctx, GuildRecord{ID: "g2", Name: "Guild Two", RawJSON: `{}`}))
 	require.NoError(t, s.UpsertChannel(ctx, ChannelRecord{ID: "c1", GuildID: "g1", Kind: "text", Name: "general", RawJSON: `{}`}))
 	require.NoError(t, s.UpsertChannel(ctx, ChannelRecord{ID: "c2", GuildID: "g1", Kind: "text", Name: "channel-c2", RawJSON: `{"source":"discord_desktop"}`}))
+	require.NoError(t, s.UpsertChannel(ctx, ChannelRecord{ID: "c3", GuildID: "g2", Kind: "text", Name: "empty", RawJSON: `{}`}))
 	require.NoError(t, s.UpsertChannel(ctx, ChannelRecord{ID: "v1", GuildID: "g1", Kind: "voice", Name: "Voice", RawJSON: `{}`}))
 	for _, message := range []MessageRecord{
+		{ID: "deleted-early", GuildID: "g1", ChannelID: "c1", CreatedAt: "2026-05-01T10:00:00Z", Content: "deleted early", NormalizedContent: "deleted early", RawJSON: `{}`},
 		{ID: "m1", GuildID: "g1", ChannelID: "c1", CreatedAt: "2026-06-01T10:00:00Z", Content: "one", NormalizedContent: "one", RawJSON: `{}`},
 		{ID: "m2", GuildID: "g1", ChannelID: "c1", CreatedAt: "2026-06-02T10:00:00Z", Content: "two", NormalizedContent: "two", RawJSON: `{}`},
 		{ID: "m3", GuildID: "g1", ChannelID: "c2", CreatedAt: "2026-06-03T10:00:00Z", Content: "three", NormalizedContent: "three", RawJSON: `{}`},
+		{ID: "deleted-late", GuildID: "g1", ChannelID: "c1", CreatedAt: "2026-07-01T10:00:00Z", Content: "deleted late", NormalizedContent: "deleted late", RawJSON: `{}`},
 	} {
 		require.NoError(t, s.UpsertMessage(ctx, message))
 	}
+	require.NoError(t, s.MarkMessageDeleted(ctx, "g1", "c1", "deleted-early", nil))
+	require.NoError(t, s.MarkMessageDeleted(ctx, "g1", "c1", "deleted-late", nil))
 	require.NoError(t, s.SetSyncState(ctx, "channel:c1:history_complete", "1"))
 	require.NoError(t, s.SetSyncState(ctx, "sync:last_success", "2026-06-04T10:00:00Z"))
 	require.NoError(t, s.SetSyncState(ctx, "wiretap:last_import", "2026-06-04T11:00:00Z"))
@@ -44,8 +50,8 @@ func TestCoverageReportsGuildChannelAndWiretapState(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, generatedAt, report.GeneratedAt)
 	require.Equal(t, CoverageTotals{
-		GuildCount: 2, MessageCount: 3, ChannelCount: 3, MessageChannelCount: 2,
-		NamedChannelCount: 2, SyntheticChannelCount: 1, HistoryCompleteChannelCount: 1,
+		GuildCount: 2, MessageCount: 3, ChannelCount: 4, MessageChannelCount: 3,
+		NamedChannelCount: 3, SyntheticChannelCount: 1, HistoryCompleteChannelCount: 1,
 		KnownFailureCount: 2, UnscopedKnownFailureCount: 1,
 	}, report.Totals)
 	require.Equal(t, time.Date(2026, 6, 4, 10, 0, 0, 0, time.UTC), report.LastBotSyncAt)
@@ -63,15 +69,92 @@ func TestCoverageReportsGuildChannelAndWiretapState(t *testing.T) {
 	require.Equal(t, 1, report.Guilds[0].KnownFailureCount)
 	require.Equal(t, 1, report.Guilds[0].Channels[0].KnownFailureCount)
 	require.True(t, report.Guilds[0].Channels[1].Synthetic)
+	require.Equal(t, "v1", report.Guilds[0].Channels[2].ID)
+	require.Equal(t, 0, report.Guilds[0].Channels[2].MessageCount)
 
-	filtered, err := s.Coverage(ctx, "g2", generatedAt)
+	filtered, err := s.Coverage(ctx, "g1", generatedAt)
 	require.NoError(t, err)
-	require.Equal(t, CoverageTotals{GuildCount: 1}, filtered.Totals)
-	require.Equal(t, "g2", filtered.Guilds[0].ID)
+	require.Equal(t, 3, filtered.Totals.MessageCount)
+	require.Equal(t, 3, filtered.Totals.ChannelCount)
+	require.Equal(t, "g1", filtered.Guilds[0].ID)
+	require.Equal(t, report.Guilds[0].Channels, filtered.Guilds[0].Channels)
+
+	empty, err := s.Coverage(ctx, "g2", generatedAt)
+	require.NoError(t, err)
+	require.Equal(t, CoverageTotals{
+		GuildCount: 1, ChannelCount: 1, MessageChannelCount: 1, NamedChannelCount: 1,
+	}, empty.Totals)
+	require.Equal(t, "c3", empty.Guilds[0].Channels[0].ID)
+	require.Equal(t, 0, empty.Guilds[0].Channels[0].MessageCount)
 	_, err = s.Coverage(ctx, "missing", generatedAt)
 	require.ErrorContains(t, err, `guild "missing" not found`)
 }
 
+func TestCoverageQueryTimeoutsAndCancellation(t *testing.T) {
+	t.Parallel()
+
+	started := time.Now()
+	globalCtx, globalCancel := withCoverageQueryTimeout(context.Background(), "")
+	globalDeadline, ok := globalCtx.Deadline()
+	require.True(t, ok)
+	require.WithinDuration(t, started.Add(8*time.Minute), globalDeadline, time.Second)
+	globalCancel()
+
+	started = time.Now()
+	filteredCtx, filteredCancel := withCoverageQueryTimeout(context.Background(), "g1")
+	filteredDeadline, ok := filteredCtx.Deadline()
+	require.True(t, ok)
+	require.WithinDuration(t, started.Add(2*time.Minute), filteredDeadline, time.Second)
+	filteredCancel()
+
+	parentDeadline := time.Now().Add(time.Minute)
+	parentCtx, parentCancel := context.WithDeadline(context.Background(), parentDeadline)
+	defer parentCancel()
+	childCtx, childCancel := withCoverageQueryTimeout(parentCtx, "")
+	defer childCancel()
+	childDeadline, ok := childCtx.Deadline()
+	require.True(t, ok)
+	require.Equal(t, parentDeadline, childDeadline)
+
+	ctx := context.Background()
+	s, err := Open(ctx, filepath.Join(t.TempDir(), "discrawl.db"))
+	require.NoError(t, err)
+	defer func() { _ = s.Close() }()
+
+	for _, guildID := range []string{"", "g1"} {
+		canceledCtx, cancel := context.WithCancel(ctx)
+		cancel()
+		_, err := s.Coverage(canceledCtx, guildID, time.Now())
+		require.ErrorIs(t, err, context.Canceled)
+	}
+}
+
+func TestCoverageGlobalQueryPlanMaterializesSequentialMessageScan(t *testing.T) {
+	ctx := context.Background()
+	s, err := Open(ctx, filepath.Join(t.TempDir(), "discrawl.db"))
+	require.NoError(t, err)
+	defer func() { require.NoError(t, s.Close()) }()
+
+	rows, err := s.DB().QueryContext(ctx, "explain query plan "+globalCoverageChannelQuery)
+	require.NoError(t, err)
+	defer func() { require.NoError(t, rows.Close()) }()
+
+	var details []string
+	for rows.Next() {
+		var selectID, parentID, unused int
+		var detail string
+		require.NoError(t, rows.Scan(&selectID, &parentID, &unused, &detail))
+		details = append(details, detail)
+	}
+	require.NoError(t, rows.Err())
+
+	plan := strings.ToLower(strings.Join(details, "\n"))
+	require.Contains(t, plan, "materialize message_coverage")
+	require.Contains(t, plan, "scan messages")
+	require.NotContains(t, plan, "idx_messages_channel_id")
+	require.NotContains(t, plan, "idx_messages_channel_created_id")
+}
+
 func TestCoverageDeltaSince(t *testing.T) {
 	previous := CoverageReport{Totals: CoverageTotals{MessageCount: 4, ChannelCount: 3, NamedChannelCount: 2, SyntheticChannelCount: 1}}
 	current := CoverageReport{Totals: CoverageTotals{MessageCount: 7, ChannelCount: 4, NamedChannelCount: 4, SyntheticChannelCount: 0}}