diff --git a/tests/test_ali_trace_pipeline.py b/tests/test_ali_trace_pipeline.py
index a484af4..588d8de 100644
--- a/tests/test_ali_trace_pipeline.py
+++ b/tests/test_ali_trace_pipeline.py
@@ -817,6 +817,74 @@ class AliTracePipelineTest(unittest.TestCase):
 
             self.assertEqual(Path(captured["dir"]), release_output_dir)
 
+    def test_export_release_ready_trace_aligns_hash_blocks_to_provider_input_length(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            root = Path(temp_dir)
+            raw_input_path = root / "trace-raw.jsonl"
+            release_output_path = root / "trace.jsonl"
+            rows = [
+                {
+                    "schema_version": "2026.04.21",
+                    "sort_time_ms": utc_ms("2026-04-17 15:00:01.000"),
+                    "meta": {
+                        "request_id": "req-pad",
+                        "model_family": "glm5",
+                        "request_ready_time_ms": utc_ms("2026-04-17 15:00:01.000"),
+                        "chat_id": 0,
+                        "parent_chat_id": -1,
+                        "turn": 1,
+                    },
+                    "canonical_prompt": "hello",
+                    "usage": {"input_tokens": 17, "output_tokens": 1},
+                },
+                {
+                    "schema_version": "2026.04.21",
+                    "sort_time_ms": utc_ms("2026-04-17 15:00:02.000"),
+                    "meta": {
+                        "request_id": "req-trim",
+                        "model_family": "glm5",
+                        "request_ready_time_ms": utc_ms("2026-04-17 15:00:02.000"),
+                        "chat_id": 1,
+                        "parent_chat_id": -1,
+                        "turn": 1,
+                    },
+                    "canonical_prompt": " ".join(str(index) for index in range(100)),
+                    "usage": {"input_tokens": 1, "output_tokens": 1},
+                },
+                {
+                    "schema_version": "2026.04.21",
+                    "sort_time_ms": utc_ms("2026-04-17 15:00:03.000"),
+                    "meta": {
+                        "request_id": "req-zero",
+                        "model_family": "glm5",
+                        "request_ready_time_ms": utc_ms("2026-04-17 15:00:03.000"),
+                        "chat_id": 2,
+                        "parent_chat_id": -1,
+                        "turn": 1,
+                    },
+                    "canonical_prompt": "hello",
+                    "usage": {"input_tokens": 0, "output_tokens": 1},
+                },
+            ]
+            raw_input_path.write_text(
+                "".join(json.dumps(row) + "\n" for row in rows),
+                encoding="utf-8",
+            )
+
+            export_release_ready_trace(
+                raw_input_path=raw_input_path,
+                release_output_path=release_output_path,
+                jobs=1,
+                block_size=8,
+            )
+
+            release_rows = [json.loads(line) for line in release_output_path.read_text(encoding="utf-8").splitlines()]
+            self.assertEqual([len(row["hash_ids"]) for row in release_rows], [3, 1, 0])
+            for row in release_rows:
+                input_length = row["input_length"]
+                expected_blocks = 0 if input_length <= 0 else (input_length + 7) // 8
+                self.assertEqual(len(row["hash_ids"]), expected_blocks)
+
     def test_format_and_sort_trace_infers_window_in_ready_time_scale_when_wall_clock_has_timezone_offset(self):
         with tempfile.TemporaryDirectory() as temp_dir:
             root = Path(temp_dir)
diff --git a/trace_formatter/formatting.py b/trace_formatter/formatting.py
index ca9e4dd..0f87993 100644
--- a/trace_formatter/formatting.py
+++ b/trace_formatter/formatting.py
@@ -539,6 +539,45 @@ def _block_digest(block: list[int]) -> bytes:
     return digest.digest()
 
 
+def _prompt_block_count_for_input_length(input_length: int, block_size: int) -> int:
+    if input_length <= 0:
+        return 0
+    return (input_length + block_size - 1) // block_size
+
+
+def _padding_block_digest_hex(*, request_identity: str, input_length: int, block_index: int) -> str:
+    digest = hashlib.blake2b(digest_size=16)
+    digest.update(b"trace_formatter.provider_input_length_padding\x00")
+    digest.update(request_identity.encode("utf-8", "ignore"))
+    digest.update(b"\x00")
+    digest.update(str(input_length).encode("ascii"))
+    digest.update(b"\x00")
+    digest.update(str(block_index).encode("ascii"))
+    return digest.hexdigest()
+
+
+def _align_digest_hexes_to_provider_input_length(
+    digest_hexes: list[str],
+    *,
+    input_length: int,
+    block_size: int,
+    request_identity: str,
+) -> list[str]:
+    target_block_count = _prompt_block_count_for_input_length(input_length, block_size)
+    if len(digest_hexes) >= target_block_count:
+        return digest_hexes[:target_block_count]
+    aligned = list(digest_hexes)
+    for block_index in range(len(aligned), target_block_count):
+        aligned.append(
+            _padding_block_digest_hex(
+                request_identity=request_identity,
+                input_length=input_length,
+                block_index=block_index,
+            )
+        )
+    return aligned
+
+
 def _load_release_tokenizer(model_family: str) -> Tokenizer:
     resolved = Path(resolve_tokenizer_path(model_family=model_family))
     tokenizer_file = resolved / "tokenizer.json" if resolved.is_dir() else resolved
@@ -637,6 +676,16 @@ def _build_release_shard(
                 digest_hexes.append(_block_digest(block).hex())
 
             core = _compute_release_row_core(row, base_ms=base_ms)
+            request_identity = str(
+                meta.get("request_id")
+                or f"{core.get('chat_id')}:{core.get('timestamp')}:{core.get('turn')}:{shard_index}:{row_count}"
+            )
+            digest_hexes = _align_digest_hexes_to_provider_input_length(
+                digest_hexes,
+                input_length=safe_int(core.get("input_length")),
+                block_size=block_size,
+                request_identity=request_identity,
+            )
             destination.write(json.dumps(core, ensure_ascii=False, separators=(",", ":")))
             destination.write("\t")
             destination.write(",".join(digest_hexes))