diff --git a/db/skill_gaps.go b/db/skill_gaps.go
new file mode 100644
index 0000000..3b6bde6
--- /dev/null
+++ b/db/skill_gaps.go
@@ -0,0 +1,51 @@
+package db
+
+import "context"
+
+// SkillGap is one skill the agent asked for but the platform did not provide,
+// aggregated by skill, agent, and task category. A miss row is written when the
+// model names a skill that does not exist (skill_usage.found=false), so this
+// report is the evidence-backed capability backlog rather than a guess.
+type SkillGap struct {
+	Skill      string `json:"skill"`
+	AgentKey   string `json:"agent_key"`
+	CategoryID int64  `json:"category_id"`
+	Misses     int    `json:"misses"`
+	Hits       int    `json:"hits"`
+	LastSeen   int64  `json:"last_seen"`
+}
+
+// SkillGaps returns the aggregated miss report, highest miss count first.
+// Hits are the successful calls for the same key, so callers can compute a
+// miss rate without a second query.
+func (d *DB) SkillGaps(ctx context.Context, limit int) ([]SkillGap, error) {
+	if limit <= 0 {
+		limit = 50
+	}
+	rows, err := d.QueryContext(ctx, `
+		SELECT su.skill,
+		       COALESCE(su.agent_key,''),
+		       COALESCE(t.category_id,0),
+		       COUNT(*) FILTER (WHERE NOT su.found) AS misses,
+		       COUNT(*) FILTER (WHERE su.found)     AS hits,
+		       EXTRACT(EPOCH FROM MAX(su.ts))::bigint
+		FROM skill_usage su
+		LEFT JOIN tasks t ON t.id=su.task_id
+		GROUP BY 1,2,3
+		HAVING COUNT(*) FILTER (WHERE NOT su.found) > 0
+		ORDER BY misses DESC, 6 DESC, 1
+		LIMIT $1`, limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	out := []SkillGap{}
+	for rows.Next() {
+		var g SkillGap
+		if err := rows.Scan(&g.Skill, &g.AgentKey, &g.CategoryID, &g.Misses, &g.Hits, &g.LastSeen); err != nil {
+			return nil, err
+		}
+		out = append(out, g)
+	}
+	return out, rows.Err()
+}
diff --git a/server/server.go b/server/server.go
index 85f837e..ca4407f 100644
--- a/server/server.go
+++ b/server/server.go
@@ -673,6 +673,7 @@ func (s *Server) Handler() http.Handler {
 
 	mux.HandleFunc("GET /api/tasks", s.listTasks)
 	mux.HandleFunc("POST /api/tasks", s.createTask)
+	mux.HandleFunc("GET /api/skill-gaps", s.skillGaps)
 	mux.HandleFunc("GET /api/task-categories", s.pgListTaskCategories)
 	mux.HandleFunc("POST /api/task-categories", s.pgCreateTaskCategory)
 	mux.HandleFunc("PATCH /api/task-categories/{id}", s.pgRenameTaskCategory)
diff --git a/server/skill_gaps.go b/server/skill_gaps.go
new file mode 100644
index 0000000..0a0b64a
--- /dev/null
+++ b/server/skill_gaps.go
@@ -0,0 +1,30 @@
+package server
+
+import (
+	"log"
+	"net/http"
+	"strconv"
+)
+
+// skillGaps reports skills the agent asked for but the platform did not
+// provide, aggregated by skill, agent, and task category. The source is the
+// existing skill_usage miss rows, so the backlog is evidence-backed rather than
+// inferred. Read-only: it creates no skill and changes no prompt.
+func (s *Server) skillGaps(w http.ResponseWriter, r *http.Request) {
+	limit := 50
+	if raw := r.URL.Query().Get("limit"); raw != "" {
+		n, err := strconv.Atoi(raw)
+		if err != nil || n < 1 || n > 500 {
+			writeErr(w, 400, "limit must be an integer between 1 and 500")
+			return
+		}
+		limit = n
+	}
+	gaps, err := s.m.PG().SkillGaps(r.Context(), limit)
+	if err != nil {
+		log.Printf("[skills] gap query failed: %v", err)
+		writeErr(w, 500, "skill gap query failed")
+		return
+	}
+	writeJSON(w, 200, map[string]any{"gaps": gaps, "count": len(gaps)})
+}
diff --git a/server/skill_gaps_test.go b/server/skill_gaps_test.go
new file mode 100644
index 0000000..bd84efe
--- /dev/null
+++ b/server/skill_gaps_test.go
@@ -0,0 +1,107 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+)
+
+func TestSkillGapsReport(t *testing.T) {
+	m, err := NewManager(t.TempDir(), "")
+	if err != nil {
+		t.Skipf("postgres unavailable (%v) — skipping", err)
+	}
+	defer m.Close()
+	task, err := m.CreateTask("skill gaps", "goal", nil, 0, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	taskID, _ := strconv.ParseInt(task.ID, 10, 64)
+	defer func() { _ = m.pg.DeleteTask(taskID) }()
+	defer func() { _, _ = m.pg.Exec(`DELETE FROM skill_usage WHERE task_id=$1`, taskID) }()
+
+	if _, err := m.pg.Exec(`
+INSERT INTO skill_usage(skill,agent_key,task_id,found) VALUES
+ ('rsi-test-graphql','worker',$1,false),
+ ('rsi-test-graphql','worker',$1,false),
+ ('rsi-test-graphql','worker',$1,true),
+ ('rsi-test-cloud','worker',$1,false),
+ ('rsi-test-known','worker',$1,true)`, taskID); err != nil {
+		t.Fatal(err)
+	}
+
+	s := New(context.Background(), m, t.TempDir(), t.TempDir(), t.TempDir())
+	token, err := signJWT(s.jwtKey)
+	if err != nil {
+		t.Fatal(err)
+	}
+	get := func(path string) *httptest.ResponseRecorder {
+		req := httptest.NewRequest(http.MethodGet, path, nil)
+		req.Header.Set("Authorization", "Bearer "+token)
+		rec := httptest.NewRecorder()
+		s.Handler().ServeHTTP(rec, req)
+		return rec
+	}
+
+	rec := get("/api/skill-gaps")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status=%d body=%s", rec.Code, rec.Body.String())
+	}
+	var out struct {
+		Gaps []struct {
+			Skill    string `json:"skill"`
+			AgentKey string `json:"agent_key"`
+			Misses   int    `json:"misses"`
+			Hits     int    `json:"hits"`
+		} `json:"gaps"`
+		Count int `json:"count"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &out); err != nil {
+		t.Fatal(err)
+	}
+	bySkill := map[string]struct {
+		misses, hits int
+		agent        string
+	}{}
+	for _, g := range out.Gaps {
+		bySkill[g.Skill] = struct {
+			misses, hits int
+			agent        string
+		}{g.Misses, g.Hits, g.AgentKey}
+	}
+	if got := bySkill["rsi-test-graphql"]; got.misses != 2 || got.hits != 1 || got.agent != "worker" {
+		t.Fatalf("graphql gap=%+v want misses=2 hits=1 agent=worker", got)
+	}
+	if got := bySkill["rsi-test-cloud"]; got.misses != 1 {
+		t.Fatalf("cloud gap=%+v want misses=1", got)
+	}
+	if _, ok := bySkill["rsi-test-known"]; ok {
+		t.Fatal("a hit-only skill must not appear in the miss report")
+	}
+	first := out.Gaps[0].Skill
+	if first != "rsi-test-graphql" {
+		t.Fatalf("ordering: first=%q want rsi-test-graphql (highest misses)", first)
+	}
+
+	rec = get("/api/skill-gaps?limit=1")
+	if rec.Code != http.StatusOK {
+		t.Fatalf("limit status=%d body=%s", rec.Code, rec.Body.String())
+	}
+	var limited struct {
+		Gaps []struct {
+			Skill string `json:"skill"`
+		} `json:"gaps"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &limited); err != nil {
+		t.Fatal(err)
+	}
+	if len(limited.Gaps) != 1 || limited.Gaps[0].Skill != "rsi-test-graphql" {
+		t.Fatalf("limit=1 returned %+v", limited.Gaps)
+	}
+	if rec := get("/api/skill-gaps?limit=abc"); rec.Code != http.StatusBadRequest {
+		t.Fatalf("bad limit status=%d want 400", rec.Code)
+	}
+}