diff --git a/sound_algo/data_only/matrix.scd b/sound_algo/data_only/matrix.scd
index 36bd5de..b9750aa 100644
--- a/sound_algo/data_only/matrix.scd
+++ b/sound_algo/data_only/matrix.scd
@@ -39,12 +39,12 @@
 // -- default color defs reproduce the historical global variation table --
 ~matDefaultColorDefs = {
     [ nil,
-        (stretch: 1.0, octave:  0, amp: 1.0,  inst: nil, cutoff: nil, pan: nil),
-        (stretch: 0.5, octave:  0, amp: 1.0,  inst: nil, cutoff: nil, pan: nil),
-        (stretch: 1.0, octave:  1, amp: 1.0,  inst: nil, cutoff: nil, pan: nil),
-        (stretch: 2.0, octave:  0, amp: 1.0,  inst: nil, cutoff: nil, pan: nil),
-        (stretch: 1.0, octave: -1, amp: 1.05, inst: nil, cutoff: nil, pan: nil),
-        (stretch: 0.5, octave:  0, amp: 1.2,  inst: nil, cutoff: nil, pan: nil) ]
+        (stretch: 1.0, octave:  0, amp: 1.0,  inst: nil, cutoff: nil, pan: nil, steps: Array.fill(16, nil)),
+        (stretch: 0.5, octave:  0, amp: 1.0,  inst: nil, cutoff: nil, pan: nil, steps: Array.fill(16, nil)),
+        (stretch: 1.0, octave:  1, amp: 1.0,  inst: nil, cutoff: nil, pan: nil, steps: Array.fill(16, nil)),
+        (stretch: 2.0, octave:  0, amp: 1.0,  inst: nil, cutoff: nil, pan: nil, steps: Array.fill(16, nil)),
+        (stretch: 1.0, octave: -1, amp: 1.05, inst: nil, cutoff: nil, pan: nil, steps: Array.fill(16, nil)),
+        (stretch: 0.5, octave:  0, amp: 1.2,  inst: nil, cutoff: nil, pan: nil, steps: Array.fill(16, nil)) ]
 };
 ~matColorDefs = ~matColorDefs ? Array.fill(~matVoices.size, { ~matDefaultColorDefs.value });
 
@@ -435,6 +435,48 @@ File.exists(~matDir).not.if({ ("mkdir -p " ++ ~matDir.quote).systemCmd });
     }
 };
 
+// -- ~matStepsEmpty : true when no step has a note (all rests) --
+~matStepsEmpty = { |steps| steps.isNil or: { steps.every({ |s| s.isNil }) } };
+
+// -- ~matSetStep : write one step (degree \rest/nil clears), re-source, echo --
+~matSetStep = { |vi, color, stepIdx, degree, vel|
+    ((vi >= 0 and: { vi < ~matVoices.size }) and: { color >= 1 and: { color <= 6 } }
+        and: { stepIdx >= 0 and: { stepIdx < 16 } }).if({
+        var steps = ~matColorDefs[vi][color][\steps];
+        ((degree == \rest) or: { degree.isNil }).if({
+            steps[stepIdx] = nil
+        }, {
+            steps[stepIdx] = (degree: degree.asInteger, vel: vel.asFloat.clip(0, 1))
+        });
+        ~matLastColor[vi] = -1;
+        (~lp[\matPlaying] and: { ~matApplyBar.notNil }).if({ ~matApplyBar.(~lp[\matBar]) });
+        ~matStepsPush.(vi, color)
+    })
+};
+
+// -- ~matStepsPush : send one color's 16 steps (degree, vel); rest -> (-99, 0) --
+~matStepsPush = { |vi, color|
+    ~toscSend !? {
+        var flat = ~matColorDefs[vi][color][\steps].collect({ |s|
+            s.isNil.if({ [-99, 0] }, { [s[\degree], s[\vel]] })
+        }).flatten;
+        ~toscSend.valueArray(["/matrix/steps", vi, color] ++ flat)
+    }
+};
+
+OSCdef(\mat_step, { |msg, time, addr|
+    var deg;
+    ~toscTouch !? { ~toscTouch.(addr) };
+    deg = ((msg[4] ? -99) == -99).if({ \rest }, { msg[4] });
+    ~matSetStep.((msg[1] ? 0).asInteger, (msg[2] ? 1).asInteger, (msg[3] ? 0).asInteger,
+        deg, (msg[5] ? 0))
+}, '/matrix/step');
+
+OSCdef(\mat_steps_get, { |msg, time, addr|
+    ~toscTouch !? { ~toscTouch.(addr) };
+    (1..6).do { |c| ~matStepsPush.((msg[1] ? 0).asInteger, c) }
+}, '/matrix/steps/get');
+
 // -- ~matModPush : send 16 mod triples (source,target,depth) flattened --
 ~matModPush = {
     ~toscSend !? {
diff --git a/sound_algo/data_only/test/test_matrix.scd b/sound_algo/data_only/test/test_matrix.scd
index 3524a83..602e3c1 100644
--- a/sound_algo/data_only/test/test_matrix.scd
+++ b/sound_algo/data_only/test/test_matrix.scd
@@ -365,6 +365,25 @@ pass = pass and: { ~matColorDefs[6][2][\inst] == \do_strike };
 
 pass = pass and: { ~matVariation.(\acid, 1, 5).asStream.next(()).notNil };
 
+// --- Step sequencer state (Task 1) ---
+pass = pass and: { ~matStepsEmpty.notNil and: { ~matSetStep.notNil and: { ~matStepsPush.notNil } } };
+// default: every color's steps is a 16-slot all-nil array -> empty
+pass = pass and: { ~matColorDefs[5][2][\steps].size == 16 };
+pass = pass and: { ~matStepsEmpty.(~matColorDefs[5][2][\steps]) };
+// set a step, then not empty; step holds degree+vel
+~trigLog = nil;
+~toscSend = { |path ...args| ~trigLog = ([path] ++ args) };
+~matSetStep.(5, 2, 3, 7, 0.8);
+pass = pass and: { ~matColorDefs[5][2][\steps][3][\degree] == 7 };
+pass = pass and: { ~matColorDefs[5][2][\steps][3][\vel] == 0.8 };
+pass = pass and: { ~matStepsEmpty.(~matColorDefs[5][2][\steps]).not };
+pass = pass and: { ~trigLog[0] == "/matrix/steps" and: { ~trigLog[1] == 5 } };
+pass = pass and: { ~trigLog.size == 35 };   // path + vi + color + 32 vals
+// rest clears the step
+~matSetStep.(5, 2, 3, \rest, 0);
+pass = pass and: { ~matColorDefs[5][2][\steps][3].isNil };
+pass = pass and: { ~matStepsEmpty.(~matColorDefs[5][2][\steps]) };
+
 pass.if(
     { "TEST PASS".postln },
     { "TEST FAIL".postln }