fix: list per-file global hunk indices in chunk prompt summaries

pr_split/diff_ops/parser.py

@@ -192,6 +192,7 @@ def stats(self) -> DiffStats:
                     is_deleted=pf.is_removed_file,
                     is_renamed=pf.is_rename,
                     hunk_count=len(pf),
+                    hunk_indices=list(range(len(pf))),
                 )
             )
         return DiffStats(

pr_split/planner/chunker.py

@@ -184,6 +184,7 @@ def build_chunk_stats_from_hunks(parsed_diff: ParsedDiff, hunk_refs: list[HunkRe
                 is_deleted=pf.is_removed_file,
                 is_renamed=pf.is_rename,
                 hunk_count=len(indices),
+                hunk_indices=sorted(indices),
             )
         )
     return DiffStats(

pr_split/planner/prompts.py

@@ -209,7 +209,17 @@ def _format_file_summary(diff_stats: DiffStats) -> str:
         ]
         flag_str = f" [{', '.join(flags)}]" if flags else ""
         hunk_count = fs["hunk_count"]
-        idx_range = f"indices 0..{hunk_count - 1}" if hunk_count > 0 else "no hunks"
+        indices = fs["hunk_indices"]
+        # In chunked mode a file's hunks in this chunk keep their per-file
+        # global indices, which need not start at 0 or be contiguous; list
+        # them explicitly so the model does not re-use indices from earlier
+        # chunks.
+        if not indices:
+            idx_range = "no hunks"
+        elif indices == list(range(len(indices))):
+            idx_range = f"indices 0..{indices[-1]}"
+        else:
+            idx_range = f"indices {', '.join(str(i) for i in indices)} (this chunk only)"
         lines.append(
             f"  {fs['path']}: +{fs['added']}/-{fs['removed']}"
             f" ({hunk_count} hunks, {idx_range}){flag_str}"

pr_split/types_defs.py

@@ -23,6 +23,7 @@ class FileSummary(TypedDict):
     is_deleted: bool
     is_renamed: bool
     hunk_count: int
+    hunk_indices: list[int]
 
 
 class ForkPRInfo(TypedDict):

tests/test_chunker.py

@@ -362,3 +362,22 @@ def test_oversized_hunk_is_pr_split_error_for_both_strategies(self) -> None:
         for strategy in (ChunkStrategy.GREEDY, ChunkStrategy.DYNAMIC_PROGRAMMING):
             with pytest.raises(PRSplitError, match=r"a\.py\[0\].*exceeds budget 100"):
                 chunk_hunks(refs, 100, strategy)
+
+
+class TestChunkStatsKeepGlobalIndices:
+    def test_second_chunk_summary_uses_per_file_global_indices(self) -> None:
+        from pr_split.diff_ops.parser import parse_diff
+        from pr_split.planner.chunker import build_chunk_stats_from_hunks, build_hunk_sequence
+        from pr_split.planner.prompts import build_chunk_continuation_prompt
+
+        diff = "diff --git a/f.py b/f.py\n--- a/f.py\n+++ b/f.py\n" + "".join(
+            f"@@ -{10 * i + 1},1 +{10 * i + 1},2 @@\n x\n+y{i}\n" for i in range(4)
+        )
+        parsed = parse_diff(diff)
+        refs = build_hunk_sequence(parsed, 0.25)
+        second_chunk = refs[2:]
+        stats = build_chunk_stats_from_hunks(parsed, second_chunk)
+        assert stats["file_summaries"][0]["hunk_indices"] == [2, 3]
+        prompt = build_chunk_continuation_prompt(stats, "diff", 2, 2, "catalog")
+        assert "indices 2, 3 (this chunk only)" in prompt
+        assert "indices 0..1" not in prompt

tests/test_prompts.py

@@ -27,6 +27,7 @@ def _make_diff_stats() -> DiffStats:
                 is_deleted=False,
                 is_renamed=False,
                 hunk_count=2,
+                hunk_indices=[0, 1],
             ),
             FileSummary(
                 path="bar.py",
@@ -36,6 +37,7 @@ def _make_diff_stats() -> DiffStats:
                 is_deleted=False,
                 is_renamed=False,
                 hunk_count=1,
+                hunk_indices=[0],
             ),
         ],
     )
@@ -101,6 +103,7 @@ def test_zero_hunk_file(self) -> None:
                     is_deleted=False,
                     is_renamed=False,
                     hunk_count=0,
+                    hunk_indices=[],
                 ),
             ],
         )
@@ -130,3 +133,28 @@ class TestBuildSystemPromptExtended:
     def test_returns_nonempty_string(self) -> None:
         result = build_system_prompt(Priority.ORTHOGONAL, 400)
         assert len(result) > 100
+
+
+class TestChunkSummaryIndices:
+    def test_later_chunk_lists_global_indices(self) -> None:
+        stats = DiffStats(
+            total_files=1,
+            total_added=1,
+            total_removed=0,
+            total_loc=1,
+            file_summaries=[
+                FileSummary(
+                    path="f.py",
+                    added=1,
+                    removed=0,
+                    is_new=False,
+                    is_deleted=False,
+                    is_renamed=False,
+                    hunk_count=2,
+                    hunk_indices=[1, 3],
+                )
+            ],
+        )
+        result = build_user_prompt(stats, "diff")
+        assert "indices 1, 3 (this chunk only)" in result
+        assert "indices 0..1" not in result

tests/test_types_defs.py

@@ -55,6 +55,7 @@ def test_dict_access(self) -> None:
             "is_deleted": False,
             "is_renamed": False,
             "hunk_count": 2,
+            "hunk_indices": [0, 1],
         }
         assert fs["path"] == "test.py"
         assert fs["added"] == 10