@@ -97,32 +97,17 @@
    @Override
    public void onPlace(BlockState state, Level level, BlockPos pos, BlockState oldState, boolean movedByPiston) {
        super.onPlace(state, level, pos, oldState, movedByPiston);
        System.out.println("[AlacrittyMC] onPlace at " + pos + " side=" + (level.isClientSide() ? "CLIENT" : "SERVER"));
        BlockEntity be = level.getBlockEntity(pos);
        if (be instanceof TerminalBlockEntity terminalBE) {
            terminalBE.rescanGroup();
            System.out.println("[AlacrittyMC]   self rescan: group=" + (terminalBE.getScreenGroup() != null
                    ? terminalBE.getScreenGroup().getGridCols() + "x" + terminalBE.getScreenGroup().getGridRows()
                    : "none") + " ext=" + terminalBE.isExtension() + " cols=" + terminalBE.getCols());
        } else {
            System.out.println("[AlacrittyMC]   NO block entity at " + pos);
        // Rescan this block only — neighbors will pick up changes via lazy client tick.
        // Don't cascade rescans here: it causes O(n²) work and can interact badly
        // with world modification during block placement.
        try {
            BlockEntity be = level.getBlockEntity(pos);
            if (be instanceof TerminalBlockEntity terminalBE) {
                terminalBE.rescanGroup();
        }
        int neighborCount = 0;
        for (Direction dir : new Direction[]{Direction.NORTH, Direction.SOUTH, Direction.EAST, Direction.WEST, Direction.UP, Direction.DOWN}) {
            BlockPos neighbor = pos.relative(dir);
            BlockEntity neighborBE = level.getBlockEntity(neighbor);
            if (neighborBE instanceof TerminalBlockEntity neighborTBE) {
                neighborTBE.rescanGroup();
                neighborCount++;
                System.out.println("[AlacrittyMC]   neighbor " + dir + " at " + neighbor
                        + ": group=" + (neighborTBE.getScreenGroup() != null
                        ? neighborTBE.getScreenGroup().getGridCols() + "x" + neighborTBE.getScreenGroup().getGridRows()
                        : "none") + " ext=" + neighborTBE.isExtension() + " cols=" + neighborTBE.getCols());
            }
        } catch (Exception e) {
            System.err.println("[AlacrittyMC] Error in onPlace rescan: " + e);
        }
        System.out.println("[AlacrittyMC]   " + neighborCount + " terminal neighbors found");
    }
    @Override

@@ -237,27 +237,41 @@
    /**
     * Called when this block is broken. Stops terminal, notifies neighbors.
     * All operations are wrapped in try-catch to prevent crashes from
     * cascading group updates during world modification.
     */
    public void onBlockRemoved() {
        try {
            stopTerminal();
        } catch (Exception e) {
        stopTerminal();
            System.err.println("[AlacrittyMC] Error stopping terminal: " + e);
        }
        // Capture and clear group state BEFORE notifying neighbors
        ScreenGroup group = this.screenGroup;
        this.screenGroup = null;
        this.controllerPos = null;
        // Notify remaining group members — clear their stale refs and let
        // Notify remaining group members to reform without this block
        // the lazy client tick rescan later (don't do cascading rescans now,
        // as the world state may be inconsistent during block breaking)
        if (level != null && group != null) {
            for (BlockPos memberPos : group.getMembers()) {
                if (memberPos.equals(getBlockPos())) continue;
                BlockEntity be = level.getBlockEntity(memberPos);
                if (be instanceof TerminalBlockEntity member) {
                    // Clear stale group references first
                    member.screenGroup = null;
                    member.controllerPos = null;
                    member.clientGroupScanned = false;
                    // Then rescan to form new group(s) without the broken block
                    member.rescanGroup();
                try {
                    BlockEntity be = level.getBlockEntity(memberPos);
                    if (be instanceof TerminalBlockEntity member) {
                        // Clear stale refs — lazy tick will rescan
                        member.screenGroup = null;
                        member.controllerPos = null;
                        member.clientGroupScanned = false;
                        member.clientTickCount = 0;
                        // If this member was running a terminal (it was
                        // the controller), the terminal is now orphaned.
                        // Don't stop it here — let the rescan handle it.
                    }
                } catch (Exception e) {
                    System.err.println("[AlacrittyMC] Error notifying neighbor at " + memberPos + ": " + e);
                }
            }
        }

@@ -126,12 +126,25 @@
    /**
     * Destroy the native terminal and free resources.
     * The actual PTY cleanup runs on a background thread to avoid
     * blocking the game thread (child process may take time to die).
     */
    @Override
    public void close() {
        if (!closed && handle != 0) {
            nativeDestroy(handle);
            final long h = handle;
            handle = 0;
            closed = true;
            // Destroy on background thread — nativeDestroy drops the Rust TerminalState
            // which kills the PTY child. This can block if the child ignores SIGHUP.
            Thread destroyThread = new Thread(() -> {
                try {
                    nativeDestroy(h);
                } catch (Exception e) {
                    System.err.println("[AlacrittyMC] Error destroying terminal: " + e);
                }
            }, "alacrittymc-destroy");
            destroyThread.setDaemon(true);
            destroyThread.start();
        }
    }

@@ -632,11 +632,12 @@
                // Break middle
                h.destroyBlock(b);
                h.runAfterDelay(5, () -> {
                    // Remaining blocks should be standalone with default dims
                    // Remaining blocks need to rescan (lazy tick hasn't fired in test)
                    TerminalBlockEntity beA = assertTerminalEntity(h, a);
                    TerminalBlockEntity beC = assertTerminalEntity(h, c);
                    beA.rescanGroup();
                    beC.rescanGroup();
                    // After neighbor notification, they should have rescanned
                    if (beA.isExtension()) throw new AssertionError("A should not be extension after break");
                    if (beC.isExtension()) throw new AssertionError("C should not be extension after break");
                    if (beA.getCols() != 80) throw new AssertionError("A cols=" + beA.getCols() + " expected 80");
@@ -758,6 +759,7 @@
            h.runAfterDelay(5, () -> {
                // Extension should become standalone
                TerminalBlockEntity survivor = assertTerminalEntity(h, extPos);
                survivor.rescanGroup(); // Trigger rescan (lazy tick hasn't fired)
                if (survivor.isExtension()) throw new AssertionError("Survivor should be standalone, not extension");
                if (survivor.getScreenGroup() != null && survivor.getScreenGroup().getMembers().size() > 1)
                    throw new AssertionError("Survivor should not be in a group");
@@ -781,8 +783,9 @@
            h.destroyBlock(extPos);
            h.runAfterDelay(5, () -> {
                TerminalBlockEntity ctrl = assertTerminalEntity(h, ctrlPos);
                // Trigger rescan (lazy tick hasn't fired in test)
                ctrl.rescanGroup();
                if (ctrl.isExtension()) throw new AssertionError("Controller should remain standalone");
                // Should revert to default single-block dims
                assertDims(ctrl, 80, 24);
                h.succeed();
            });
@@ -802,6 +805,8 @@
            h.runAfterDelay(5, () -> {
                TerminalBlockEntity beA = assertTerminalEntity(h, a);
                TerminalBlockEntity beC = assertTerminalEntity(h, c);
                beA.rescanGroup();
                beC.rescanGroup();
                if (beA.isExtension()) throw new AssertionError("A should be standalone");
                if (beC.isExtension()) throw new AssertionError("C should be standalone");
                h.succeed();

@@ -200,13 +200,32 @@
        System.out.println("[VisualTest] === SCREENSHOT & ANALYSIS ===");
        try {
            // Log terminal states
            // Log terminal states — detailed per-block renderer diagnosis
            logTerminalState(mc, "Single", singlePos);
            if (multiOrigin != null) {
                for (int x = 0; x < MULTI_W; x++) {
                    for (int y = 0; y < MULTI_H; y++) {
                        BlockPos p = new BlockPos(multiOrigin.getX() + x, multiOrigin.getY() + y, multiOrigin.getZ());
                        logTerminalState(mc, "Multi[" + x + "," + y + "]", p);
                        // Simulate what the renderer would do
                        var gbe = mc.level.getBlockEntity(p);
                        if (gbe instanceof io.fangorn.alacrittymc.block.TerminalBlockEntity tbe) {
                            var ctrl = tbe.getController();
                            boolean wouldRenderTerminal = ctrl != null && ctrl.isTerminalRunning()
                                    && ctrl.getPixelWidth() > 0 && ctrl.getPixelHeight() > 0;
                            var group = tbe.getScreenGroup();
                            String uvInfo = "none";
                            if (group != null) {
                                float[] uv = group.getSubRegion(tbe.getBlockPos());
                                uvInfo = String.format("u=[%.2f,%.2f] v=[%.2f,%.2f]", uv[0], uv[1], uv[2], uv[3]);
                            }
                            System.out.println("[VisualTest]   renderer: wouldRenderTerminal=" + wouldRenderTerminal
                                    + " ctrlAt=" + (ctrl != null ? ctrl.getBlockPos() : "null")
                                    + " ctrlRunning=" + (ctrl != null && ctrl.isTerminalRunning())
                                    + " ctrlPx=" + (ctrl != null ? ctrl.getPixelWidth() + "x" + ctrl.getPixelHeight() : "0x0")
                                    + " uv=" + uvInfo);
                        }
                    }
                }
            }