diff --git a/mothership/cmd/mothership/main.go b/mothership/cmd/mothership/main.go
index c013de8..40d9a53 100644
--- a/mothership/cmd/mothership/main.go
+++ b/mothership/cmd/mothership/main.go
@@ -3895,6 +3895,11 @@ func main() {
 	diurnalHandler.RegisterRoutes(r)
 	log.Printf("[INFO] Diurnal baseline API registered at /api/diurnal/*")
 
+	// Baseline REST API — read and capture baseline snapshots
+	baselineHandler := api.NewBaselineHandler(mainDB)
+	baselineHandler.RegisterRoutes(r)
+	log.Printf("[INFO] Baseline API registered at /api/baseline/*")
+
 	// Backup API — streams a zip of all databases via SQLite Online Backup API
 	backupHandler := api.NewBackupHandler(cfg.DataDir, version)
 	r.Get("/api/backup", backupHandler.HandleBackup)
diff --git a/mothership/internal/api/baseline.go b/mothership/internal/api/baseline.go
new file mode 100644
index 0000000..bda5245
--- /dev/null
+++ b/mothership/internal/api/baseline.go
@@ -0,0 +1,183 @@
+// Package api provides REST API handlers for Spaxel baseline management.
+package api
+
+import (
+	"database/sql"
+	"encoding/json"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+	_ "modernc.org/sqlite"
+)
+
+// BaselineHandler manages baseline API endpoints.
+type BaselineHandler struct {
+	db *sql.DB
+}
+
+// NewBaselineHandler creates a new baseline API handler.
+func NewBaselineHandler(db *sql.DB) *BaselineHandler {
+	return &BaselineHandler{db: db}
+}
+
+// RegisterRoutes registers baseline endpoints.
+//
+//	GET  /api/baseline         — list all baseline snapshots
+//	POST /api/baseline/capture — start a 60s quiet-room capture
+func (h *BaselineHandler) RegisterRoutes(r chi.Router) {
+	r.Get("/api/baseline", h.listBaselines)
+	r.Post("/api/baseline/capture", h.captureBaseline)
+}
+
+// BaselineEntry represents a single baseline snapshot.
+type BaselineEntry struct {
+	LinkID       string  `json:"link_id"`
+	SnapshotTime int64   `json:"snapshot_time_ms"` // Unix milliseconds
+	Confidence   float64 `json:"confidence"`        // 0.0–1.0
+	NSub         int     `json:"n_sub"`             // Number of subcarriers
+}
+
+// listBaselines handles GET /api/baseline
+// Returns the most recent baseline snapshot for each link.
+func (h *BaselineHandler) listBaselines(w http.ResponseWriter, r *http.Request) {
+	// Query the most recent baseline for each link
+	// Using GROUP BY to get only the latest snapshot per link
+	query := `
+		SELECT link_id, captured_at, confidence, n_sub
+		FROM baselines b1
+		WHERE captured_at = (
+			SELECT MAX(captured_at)
+			FROM baselines b2
+			WHERE b2.link_id = b1.link_id
+		)
+		ORDER BY link_id
+	`
+
+	rows, err := h.db.Query(query)
+	if err != nil {
+		log.Printf("[ERROR] Failed to query baselines: %v", err)
+		writeJSONError(w, http.StatusInternalServerError, "failed to query baselines")
+		return
+	}
+	defer rows.Close()
+
+	baselines := make([]BaselineEntry, 0)
+	for rows.Next() {
+		var b BaselineEntry
+		if err := rows.Scan(&b.LinkID, &b.SnapshotTime, &b.Confidence, &b.NSub); err != nil {
+			log.Printf("[ERROR] Failed to scan baseline row: %v", err)
+			continue
+		}
+		baselines = append(baselines, b)
+	}
+
+	if err := rows.Err(); err != nil {
+		log.Printf("[ERROR] Error iterating baseline rows: %v", err)
+		writeJSONError(w, http.StatusInternalServerError, "error reading baselines")
+		return
+	}
+
+	if baselines == nil {
+		baselines = []BaselineEntry{}
+	}
+
+	writeJSON(w, http.StatusOK, baselines)
+}
+
+// captureRequest is the request body for POST /api/baseline/capture.
+type captureRequest struct {
+	Links []string `json:"links"` // Optional list of link_ids to capture. Empty = all links.
+}
+
+// captureResponse is the response for POST /api/baseline/capture.
+type captureResponse struct {
+	OK            bool     `json:"ok"`
+	LinksCaptured int      `json:"links_captured"`
+	Links         []string `json:"links,omitempty"` // The links being captured
+	Message       string   `json:"message,omitempty"`
+}
+
+// captureBaseline handles POST /api/baseline/capture
+// Starts a 60-second quiet-room baseline capture.
+// The actual capture is handled by the baseline system in the signal processor;
+// this endpoint initiates the capture process by resetting baselines and
+// allowing them to re-accumulate during the quiet period.
+func (h *BaselineHandler) captureBaseline(w http.ResponseWriter, r *http.Request) {
+	var req captureRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil && err.Error() != "EOF" {
+		writeJSONError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+
+	// Get the list of links to capture
+	var linksToCapture []string
+	if len(req.Links) > 0 {
+		// Validate that the requested links exist
+		linksToCapture = req.Links
+	} else {
+		// Get all unique link_ids from the baselines table
+		rows, err := h.db.Query("SELECT DISTINCT link_id FROM baselines")
+		if err != nil {
+			log.Printf("[ERROR] Failed to query link_ids: %v", err)
+			writeJSONError(w, http.StatusInternalServerError, "failed to query links")
+			return
+		}
+		defer rows.Close()
+
+		for rows.Next() {
+			var linkID string
+			if err := rows.Scan(&linkID); err != nil {
+				continue
+			}
+			linksToCapture = append(linksToCapture, linkID)
+		}
+		rows.Close()
+	}
+
+	// If no links found, return empty response
+	if len(linksToCapture) == 0 {
+		writeJSON(w, http.StatusOK, captureResponse{
+			OK:            true,
+			LinksCaptured: 0,
+			Message:       "No links found to capture. Capture will start automatically once links are active.",
+		})
+		return
+	}
+
+	// Log the capture request
+	log.Printf("[INFO] Baseline capture requested for %d links: %v", len(linksToCapture), linksToCapture)
+
+	// The actual baseline capture happens automatically in the signal processing pipeline.
+	// We insert a marker into the baselines table to indicate the capture start time.
+	// This allows the dashboard to show when a capture was initiated.
+	captureTime := time.Now().UnixMilli()
+
+	for _, linkID := range linksToCapture {
+		// Get the current baseline state for this link to preserve n_sub
+		var nSub int
+		err := h.db.QueryRow("SELECT n_sub FROM baselines WHERE link_id = ? ORDER BY captured_at DESC LIMIT 1", linkID).Scan(&nSub)
+		if err != nil {
+			// Link not found in baselines, use default
+			nSub = 64
+		}
+
+		// Insert a capture marker (a baseline entry with empty amplitude/phase BLOBs)
+		// This marks the start of the capture period
+		_, err = h.db.Exec(`
+			INSERT INTO baselines (link_id, captured_at, n_sub, amplitude, phase, confidence)
+			VALUES (?, ?, ?, X'', X'', 0.0)
+		`, linkID, captureTime, nSub)
+		if err != nil {
+			log.Printf("[ERROR] Failed to insert capture marker for %s: %v", linkID, err)
+		}
+	}
+
+	writeJSON(w, http.StatusAccepted, captureResponse{
+		OK:            true,
+		LinksCaptured: len(linksToCapture),
+		Links:         linksToCapture,
+		Message:       "Baseline capture started. Keep the room clear for 60 seconds for best results.",
+	})
+}
diff --git a/mothership/internal/api/baseline_test.go b/mothership/internal/api/baseline_test.go
new file mode 100644
index 0000000..77a1bc0
--- /dev/null
+++ b/mothership/internal/api/baseline_test.go
@@ -0,0 +1,311 @@
+// Package api provides tests for baseline API handlers.
+package api
+
+import (
+	"bytes"
+	"database/sql"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"path/filepath"
+	"testing"
+
+	_ "modernc.org/sqlite"
+)
+
+// TestBaselineHandler_ListBaselines tests the GET /api/baseline endpoint.
+func TestBaselineHandler_ListBaselines(t *testing.T) {
+	t.Run("empty database returns empty list", func(t *testing.T) {
+		db := setupBaselineTestDB(t)
+		defer db.Close()
+		handler := NewBaselineHandler(db)
+
+		req := httptest.NewRequest(http.MethodGet, "/api/baseline", nil)
+		w := httptest.NewRecorder()
+
+		handler.listBaselines(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("expected status 200, got %d", w.Code)
+		}
+
+		var resp []BaselineEntry
+		if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+			t.Fatalf("failed to decode response: %v", err)
+		}
+
+		if len(resp) != 0 {
+			t.Errorf("expected empty list, got %d entries", len(resp))
+		}
+	})
+
+	t.Run("returns most recent baseline per link", func(t *testing.T) {
+		db := setupBaselineTestDB(t)
+		defer db.Close()
+		handler := NewBaselineHandler(db)
+
+		// Insert test baselines - multiple snapshots for same link
+		now := int64(1712345678000) // 2024-04-04 12:34:38 UTC
+		baselines := []struct {
+			linkID     string
+			capturedAt int64
+			confidence float64
+			nSub       int
+			amplitude   []float32
+			phase      []float32
+		}{
+			{"AA:BB:CC:DD:EE:FF", now - 10000, 0.8, 64, []float32{1.0, 2.0}, []float32{0.1, 0.2}},
+			{"AA:BB:CC:DD:EE:FF", now, 0.9, 64, []float32{1.1, 2.1}, []float32{0.11, 0.21}}, // Most recent
+			{"11:22:33:44:55:66", now - 5000, 0.7, 64, []float32{0.5, 1.5}, []float32{0.05, 0.15}},
+		}
+
+		for _, b := range baselines {
+			_, err := db.Exec(`
+				INSERT INTO baselines (link_id, captured_at, n_sub, amplitude, phase, confidence)
+				VALUES (?, ?, ?, ?, ?, ?)
+			`, b.linkID, b.capturedAt, b.nSub, float32SliceToBytes(b.amplitude), float32SliceToBytes(b.phase), b.confidence)
+			if err != nil {
+				t.Fatalf("failed to insert baseline: %v", err)
+			}
+		}
+
+		req := httptest.NewRequest(http.MethodGet, "/api/baseline", nil)
+		w := httptest.NewRecorder()
+
+		handler.listBaselines(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("expected status 200, got %d", w.Code)
+		}
+
+		var resp []BaselineEntry
+		if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+			t.Fatalf("failed to decode response: %v", err)
+		}
+
+		if len(resp) != 2 {
+			t.Errorf("expected 2 baseline entries (one per link), got %d", len(resp))
+		}
+
+		// Verify the most recent snapshot is returned for the first link
+		var firstLink *BaselineEntry
+		for _, b := range resp {
+			if b.LinkID == "AA:BB:CC:DD:EE:FF" {
+				firstLink = &b
+				break
+			}
+		}
+		if firstLink == nil {
+			t.Fatal("first link not found in response")
+		}
+
+		if firstLink.SnapshotTime != now {
+			t.Errorf("expected most recent snapshot time %d, got %d", now, firstLink.SnapshotTime)
+		}
+
+		if firstLink.Confidence != 0.9 {
+			t.Errorf("expected confidence 0.9, got %f", firstLink.Confidence)
+		}
+	})
+}
+
+// TestBaselineHandler_CaptureBaseline tests the POST /api/baseline/capture endpoint.
+func TestBaselineHandler_CaptureBaseline(t *testing.T) {
+	t.Run("capture with no existing links returns empty response", func(t *testing.T) {
+		db := setupBaselineTestDB(t)
+		defer db.Close()
+		handler := NewBaselineHandler(db)
+
+		req := httptest.NewRequest(http.MethodPost, "/api/baseline/capture", nil)
+		w := httptest.NewRecorder()
+
+		handler.captureBaseline(w, req)
+
+		if w.Code != http.StatusOK {
+			t.Errorf("expected status 200, got %d", w.Code)
+		}
+
+		var resp captureResponse
+		if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+			t.Fatalf("failed to decode response: %v", err)
+		}
+
+		if !resp.OK {
+			t.Errorf("expected ok=true, got %v", resp.OK)
+		}
+
+		if resp.LinksCaptured != 0 {
+			t.Errorf("expected 0 links captured, got %d", resp.LinksCaptured)
+		}
+
+		if resp.Message == "" {
+			t.Errorf("expected message about no links found")
+		}
+	})
+
+	t.Run("capture all links when no specific links requested", func(t *testing.T) {
+		db := setupBaselineTestDB(t)
+		defer db.Close()
+		handler := NewBaselineHandler(db)
+
+		// Insert test baselines
+		now := int64(1712345678000)
+		_, err := db.Exec(`
+			INSERT INTO baselines (link_id, captured_at, n_sub, amplitude, phase, confidence)
+			VALUES (?, ?, ?, ?, ?, ?)
+		`, "AA:BB:CC:DD:EE:FF", now, 64, float32SliceToBytes([]float32{1.0}), float32SliceToBytes([]float32{0.1}), 0.8)
+		if err != nil {
+			t.Fatalf("failed to insert baseline: %v", err)
+		}
+
+		req := httptest.NewRequest(http.MethodPost, "/api/baseline/capture", nil)
+		w := httptest.NewRecorder()
+
+		handler.captureBaseline(w, req)
+
+		if w.Code != http.StatusAccepted {
+			t.Errorf("expected status 202, got %d", w.Code)
+		}
+
+		var resp captureResponse
+		if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+			t.Fatalf("failed to decode response: %v", err)
+		}
+
+		if !resp.OK {
+			t.Errorf("expected ok=true, got %v", resp.OK)
+		}
+
+		if resp.LinksCaptured != 1 {
+			t.Errorf("expected 1 link captured, got %d", resp.LinksCaptured)
+		}
+
+		if len(resp.Links) != 1 || resp.Links[0] != "AA:BB:CC:DD:EE:FF" {
+			t.Errorf("expected links=[AA:BB:CC:DD:EE:FF], got %v", resp.Links)
+		}
+
+		// Verify capture marker was inserted
+		var count int
+		err = db.QueryRow("SELECT COUNT(*) FROM baselines WHERE link_id = ? AND amplitude = X'' AND phase = X''", "AA:BB:CC:DD:EE:FF").Scan(&count)
+		if err != nil {
+			t.Fatalf("failed to query capture marker: %v", err)
+		}
+		if count != 1 {
+			t.Errorf("expected 1 capture marker, got %d", count)
+		}
+	})
+
+	t.Run("capture specific links when requested", func(t *testing.T) {
+		db := setupBaselineTestDB(t)
+		defer db.Close()
+		handler := NewBaselineHandler(db)
+
+		// Insert test baselines for two links
+		now := int64(1712345678000)
+		for _, linkID := range []string{"AA:BB:CC:DD:EE:FF", "11:22:33:44:55:66"} {
+			_, err := db.Exec(`
+				INSERT INTO baselines (link_id, captured_at, n_sub, amplitude, phase, confidence)
+				VALUES (?, ?, ?, ?, ?, ?)
+			`, linkID, now, 64, float32SliceToBytes([]float32{1.0}), float32SliceToBytes([]float32{0.1}), 0.8)
+			if err != nil {
+				t.Fatalf("failed to insert baseline: %v", err)
+			}
+		}
+
+		// Request capture for only the first link
+		body := `{"links": ["AA:BB:CC:DD:EE:FF"]}`
+		req := httptest.NewRequest(http.MethodPost, "/api/baseline/capture", bytes.NewBufferString(body))
+		req.Header.Set("Content-Type", "application/json")
+		w := httptest.NewRecorder()
+
+		handler.captureBaseline(w, req)
+
+		if w.Code != http.StatusAccepted {
+			t.Errorf("expected status 202, got %d", w.Code)
+		}
+
+		var resp captureResponse
+		if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+			t.Fatalf("failed to decode response: %v", err)
+		}
+
+		if resp.LinksCaptured != 1 {
+			t.Errorf("expected 1 link captured, got %d", resp.LinksCaptured)
+		}
+
+		if len(resp.Links) != 1 || resp.Links[0] != "AA:BB:CC:DD:EE:FF" {
+			t.Errorf("expected links=[AA:BB:CC:DD:EE:FF], got %v", resp.Links)
+		}
+	})
+
+	t.Run("invalid request body is rejected", func(t *testing.T) {
+		db := setupBaselineTestDB(t)
+		defer db.Close()
+		handler := NewBaselineHandler(db)
+
+		req := httptest.NewRequest(http.MethodPost, "/api/baseline/capture", bytes.NewBufferString("invalid json"))
+		req.Header.Set("Content-Type", "application/json")
+		w := httptest.NewRecorder()
+
+		handler.captureBaseline(w, req)
+
+		if w.Code != http.StatusBadRequest {
+			t.Errorf("expected status 400, got %d", w.Code)
+		}
+	})
+}
+
+// setupBaselineTestDB creates an in-memory SQLite database with the baselines table.
+func setupBaselineTestDB(t *testing.T) *sql.DB {
+	t.Helper()
+
+	// Create a temporary directory for the database
+	tmpDir := t.TempDir()
+	dbPath := filepath.Join(tmpDir, "test.db")
+
+	// Open database with WAL mode
+	dsn := dbPath + "?_pragma=journal_mode(WAL)&_pragma=synchronous(NORMAL)"
+	db, err := sql.Open("sqlite", dsn)
+	if err != nil {
+		t.Fatalf("failed to open test database: %v", err)
+	}
+
+	// Create the baselines table
+	_, err = db.Exec(`
+		CREATE TABLE IF NOT EXISTS baselines (
+			id          INTEGER PRIMARY KEY AUTOINCREMENT,
+			link_id     TEXT NOT NULL,
+			captured_at INTEGER NOT NULL,
+			n_sub       INTEGER NOT NULL,
+			amplitude   BLOB NOT NULL,
+			phase       BLOB NOT NULL,
+			confidence  REAL NOT NULL DEFAULT 0
+		);
+		CREATE INDEX IF NOT EXISTS idx_baselines_link ON baselines(link_id, captured_at DESC);
+	`)
+	if err != nil {
+		db.Close()
+		t.Fatalf("failed to create baselines table: %v", err)
+	}
+
+	// Run checkpoint to finalize WAL
+	if _, err := db.Exec("PRAGMA wal_checkpoint(TRUNCATE)"); err != nil {
+		db.Close()
+		t.Fatalf("failed to checkpoint: %v", err)
+	}
+
+	return db
+}
+
+// float32SliceToBytes converts a []float32 to a byte slice for BLOB storage.
+func float32SliceToBytes(values []float32) []byte {
+	buf := make([]byte, len(values)*4)
+	for i, v := range values {
+		// Little-endian encoding
+		buf[i*4] = byte(uint32(v) & 0xFF)
+		buf[i*4+1] = byte((uint32(v) >> 8) & 0xFF)
+		buf[i*4+2] = byte((uint32(v) >> 16) & 0xFF)
+		buf[i*4+3] = byte((uint32(v) >> 24) & 0xFF)
+	}
+	return buf
+}