diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..5045453
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,19 @@
+# Changelog
+
+## Unreleased
+
+- Fix PT-P710BT/PT-P900W print completion flow and protocol bytes.
+  - Correct `G` raster transfer header length (`n1/n2`) from per-model payload size.
+  - Fix `ESC i z` page index (`n9`) and adjust print-information flags/media kind handling.
+  - Keep `ESC i A` disabled on 128-dot family and split `ESC i K` by head width.
+  - Use `0x0C -> 0x1A` end sequence on 560-dot family to complete feed/cut reliably.
+- Improve status handling around print completion.
+  - Retry status reads with backoff and safer command ordering.
+  - Add verbose post-print short polling until print-end status is observed.
+  - Add small wait before `--status` command retrieval.
+- Add protocol regression safeguards.
+  - Introduce `libptouch_protocol` helpers for shared command-byte generation.
+  - Add `protocol_regression_test` and wire it into CTest.
+- Update documentation.
+  - Add `ctest` step to build instructions.
+  - Link to changelog from README.
diff --git a/README.md b/README.md
index 2fc2188..1886f1b 100644
--- a/README.md
+++ b/README.md
@@ -120,4 +120,8 @@ sudo usermod -aG plugdev "$USER"
 
 ## ライセンス
 
-[MIT License](LICENSE)（`LICENSE` ファイルを参照）。
\ No newline at end of file
+[MIT License](LICENSE)（`LICENSE` ファイルを参照）。
+
+## 変更履歴
+
+リリース間の変更点は `CHANGELOG.md` を参照してください。
\ No newline at end of file
diff --git a/src/cli/main.c b/src/cli/main.c
index 4ed60e1..1cf1ea1 100644
--- a/src/cli/main.c
+++ b/src/cli/main.c
@@ -13,6 +13,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <strings.h>
+#include <unistd.h>
 
 static void usage(const char *argv0)
 {
@@ -141,12 +142,28 @@ static void verbose_print_post_print_status(libptouch_ctx *ctx, const char *labe
 	if (!ctx)
 		return;
 	printf("=== verbose: post-print status (%s) ===\n", label);
-	uint8_t st[LIBPTOUCH_STATUS_LENGTH];
-	if (libptouch_get_status(ctx, st) == LIBPTOUCH_OK) {
-		libptouch_status_fprint(stdout, st);
-	} else {
-		printf("status: unavailable (%s)\n", libptouch_strerror(ctx));
+	/*
+	 * 印刷直後は phase change (status[18] != 0x00) が続くことがあるため、
+	 * 短時間ポーリングで最終状態まで追跡する。
+	 */
+	const int max_polls = 12; /* ~2.4s */
+	const useconds_t poll_interval_us = 200000;
+	for (int i = 0; i < max_polls; i++) {
+		uint8_t st[LIBPTOUCH_STATUS_LENGTH];
+		if (libptouch_get_status(ctx, st) != LIBPTOUCH_OK) {
+			printf("status poll %d/%d: unavailable (%s)\n", i + 1,
+			       max_polls, libptouch_strerror(ctx));
+		} else {
+			printf("status poll %d/%d:\n", i + 1, max_polls);
+			libptouch_status_fprint(stdout, st);
+			if (st[18] == 0x00u) {
+				printf("post-print polling settled: print end.\n");
+				return;
+			}
+		}
+		usleep(poll_interval_us);
 	}
+	printf("post-print polling timeout: phase did not settle.\n");
 }
 
 int main(int argc, char **argv)
@@ -261,6 +278,10 @@ int main(int argc, char **argv)
 			libptouch_destroy(sctx);
 			return 1;
 		}
+		/* 印刷直後などは内部処理中で最初のステータス応答が不安定なことがあるため、
+		 * 少し待ってからステータスを取りに行く。 */
+		usleep(300000); /* 300ms */
+
 		uint8_t st[LIBPTOUCH_STATUS_LENGTH];
 		se = libptouch_get_status(sctx, st);
 		if (se != LIBPTOUCH_OK) {
diff --git a/src/lib/libptouch_print.c b/src/lib/libptouch_print.c
index c9bcbc1..dcc22ed 100644
--- a/src/lib/libptouch_print.c
+++ b/src/lib/libptouch_print.c
@@ -171,8 +171,7 @@ libptouch_err_t libptouch_print_raster(libptouch_ctx *ctx,
 		pos += sizeof(esc_ia);
 	}
 
-	/* Chain printing off; safer default for 128-dot family as well. */
-	static const uint8_t esc_ik[] = { 0x1B, 0x69, 0x4B, 0x08 };
+	uint8_t esc_ik[] = { 0x1B, 0x69, 0x4B, ptouch_esc_ik_value(head_dots) };
 	memcpy(head + pos, esc_ik, sizeof(esc_ik));
 	pos += sizeof(esc_ik);
 
@@ -218,6 +217,21 @@ libptouch_err_t libptouch_print_raster(libptouch_ctx *ctx,
 	}
 	free(gbuf);
 
+	/*
+	 * Some 560-dot family devices are sensitive to end-of-page sequencing.
+	 * Send FF (0x0C) then Control-Z (0x1A) on that family to explicitly
+	 * terminate page and final feed/cut.
+	 */
+	if (head_dots > 128u) {
+		static const uint8_t page_end[] = { 0x0C };
+		v = ptouch_bulk_send_job(ctx, page_end, sizeof(page_end),
+					 "print page end");
+		if (v != LIBPTOUCH_OK) {
+			free(transposed);
+			return v;
+		}
+	}
+
 	static const uint8_t print_end[] = { 0x1A };
 	v = ptouch_bulk_send_job(ctx, print_end, sizeof(print_end), "print end");
 	if (v != LIBPTOUCH_OK) {
diff --git a/src/lib/libptouch_protocol.c b/src/lib/libptouch_protocol.c
index 15b767e..4c762f2 100644
--- a/src/lib/libptouch_protocol.c
+++ b/src/lib/libptouch_protocol.c
@@ -15,21 +15,13 @@ void ptouch_fill_gf_header(uint8_t out[3], size_t line_payload_bytes)
 void ptouch_fill_esc_iz(uint8_t out[13], uint8_t media_kind, uint8_t media_width,
 			uint32_t raster_lines)
 {
-	uint8_t n2_paper = 0x09u;
-	if (media_kind == 0x03u)
-		n2_paper = 0x00u;
-	else if (media_kind == 0x11u)
-		n2_paper = 0x11u;
-	else if (media_kind == 0x17u)
-		n2_paper = 0x17u;
-	else if (media_kind == 0x13u)
-		n2_paper = 0x13u;
-
 	out[0] = 0x1Bu;
 	out[1] = 0x69u;
 	out[2] = 0x7Au;
-	out[3] = 0x0Eu;
-	out[4] = n2_paper;
+	/* PI flags: enable media/width/length with quality bit for broad compatibility. */
+	out[3] = 0x8Eu;
+	/* Use status media-kind byte directly (e.g., 0x01 laminated, 0x03 non-laminate). */
+	out[4] = media_kind;
 	out[5] = media_width;
 	out[6] = 0x00u;
 	out[7] = (uint8_t)(raster_lines & 0xFFu);
@@ -39,3 +31,9 @@ void ptouch_fill_esc_iz(uint8_t out[13], uint8_t media_kind, uint8_t media_width
 	out[11] = 0x00u; /* first page */
 	out[12] = 0x00u; /* fixed */
 }
+
+uint8_t ptouch_esc_ik_value(unsigned head_dots)
+{
+	/* Preserve legacy 560-dot behaviour (0x0C), 128-dot uses 0x08. */
+	return head_dots > 128u ? 0x0Cu : 0x08u;
+}
diff --git a/src/lib/libptouch_protocol.h b/src/lib/libptouch_protocol.h
index 702e6be..054a86e 100644
--- a/src/lib/libptouch_protocol.h
+++ b/src/lib/libptouch_protocol.h
@@ -8,5 +8,6 @@ size_t ptouch_line_payload_bytes(unsigned head_dots);
 void ptouch_fill_gf_header(uint8_t out[3], size_t line_payload_bytes);
 void ptouch_fill_esc_iz(uint8_t out[13], uint8_t media_kind, uint8_t media_width,
 			uint32_t raster_lines);
+uint8_t ptouch_esc_ik_value(unsigned head_dots);
 
 #endif /* LIBPTOUCH_PROTOCOL_H */
diff --git a/src/lib/libptouch_status.c b/src/lib/libptouch_status.c
index 07d37b8..bddf738 100644
--- a/src/lib/libptouch_status.c
+++ b/src/lib/libptouch_status.c
@@ -36,13 +36,21 @@ libptouch_err_t libptouch_get_status(libptouch_ctx *ctx, uint8_t *status)
 		if (attempt > 0) {
 			usleep(120000); /* 120ms backoff */
 		}
-		r = ptouch_bulk_out(h, ctx->bulk_out_ep, init, 2, 5000u);
-		if (r != 0) {
-			if (r == LIBUSB_ERROR_IO || r == LIBUSB_ERROR_PIPE ||
-			    r == LIBUSB_ERROR_TIMEOUT)
-				continue;
-			ptouch_set_error_usb(ctx, r, "bulk OUT ESC @");
-			return LIBPTOUCH_ERR_USB;
+		/*
+		 * Avoid unconditional ESC @ here:
+		 * some models can be in phase-change right after print end, and
+		 * re-initializing there may disturb cutter/feed completion.
+		 * Try plain ESC i S first, use ESC @ only on retry paths.
+		 */
+		if (attempt > 0) {
+			r = ptouch_bulk_out(h, ctx->bulk_out_ep, init, 2, 5000u);
+			if (r != 0) {
+				if (r == LIBUSB_ERROR_IO || r == LIBUSB_ERROR_PIPE ||
+				    r == LIBUSB_ERROR_TIMEOUT)
+					continue;
+				ptouch_set_error_usb(ctx, r, "bulk OUT ESC @");
+				return LIBPTOUCH_ERR_USB;
+			}
 		}
 		r = ptouch_bulk_out(h, ctx->bulk_out_ep, req, 3, 5000u);
 		if (r != 0) {
diff --git a/tests/protocol_regression_test.c b/tests/protocol_regression_test.c
index 1ac0ba2..d495287 100644
--- a/tests/protocol_regression_test.c
+++ b/tests/protocol_regression_test.c
@@ -34,11 +34,16 @@ int main(void)
 	fail |= expect_int("iz_cmd_0", iz[0], 0x1B);
 	fail |= expect_int("iz_cmd_1", iz[1], 0x69);
 	fail |= expect_int("iz_cmd_2", iz[2], 0x7A);
-	fail |= expect_int("iz_media_kind_map", iz[4], 0x09);
+	fail |= expect_int("iz_n1_flags", iz[3], 0x8E);
+	fail |= expect_int("iz_media_kind_passthrough", iz[4], 0x01);
 	fail |= expect_int("iz_media_width", iz[5], 0x0C);
 	fail |= expect_int("iz_lines_lsb", iz[7], 70);
 	fail |= expect_int("iz_page_index", iz[11], 0x00);
 	fail |= expect_int("iz_last_fixed", iz[12], 0x00);
 
+	/* ESC i K mode byte: 128-dot vs 560-dot families */
+	fail |= expect_int("esc_ik_128", ptouch_esc_ik_value(128u), 0x08);
+	fail |= expect_int("esc_ik_560", ptouch_esc_ik_value(560u), 0x0C);
+
 	return fail ? EXIT_FAILURE : EXIT_SUCCESS;
 }