2 files changed, 43 insertions, 31 deletions

diff --git a/assemble-pro-review-package/SKILL.md b/assemble-pro-review-package/SKILL.md
index b571fde..d73ffbb 100644
--- a/assemble-pro-review-package/SKILL.md
+++ b/assemble-pro-review-package/SKILL.md
@@ -19,7 +19,7 @@ artifacts, or companion files. If a textual artifact cannot be inlined under the
 cut it.
 
 Use `scripts/inline_section.py` to append labeled sections into the document and enforce
-the skill's fixed hard ceiling of 100k tokens, counted with `o200k_base`. It is not an
+the skill's fixed hard ceiling of 75k tokens, counted with `o200k_base`. It is not an
 objective to reduce the token count, and there is no harm in going all the way up to the
 limit if the material being included is genuinely relevant and the problem is complex.
 Spend the ceiling on material that sharpens the review question. Cut material whose
diff --git a/assemble-pro-review-package/scripts/inline_section.py b/assemble-pro-review-package/scripts/inline_section.py
index 23daaf0..3356646 100755
--- a/assemble-pro-review-package/scripts/inline_section.py
+++ b/assemble-pro-review-package/scripts/inline_section.py
@@ -7,7 +7,11 @@
 from __future__ import annotations
 
 import argparse
+import contextlib
+import fcntl
 import sys
+import tempfile
+from collections.abc import Iterator
 from pathlib import Path
 
 import tiktoken
@@ -48,14 +52,15 @@ LANGUAGE_BY_SUFFIX = {
     ".yml": "yaml",
 }
 
-HARD_MAX_TOKENS = 100_000
+HARD_MAX_TOKENS = 75_000
+GLOBAL_APPEND_LOCK = Path(tempfile.gettempdir()) / "assemble-pro-review-package-inline-section.lock"
 
 
 def parse_args() -> argparse.Namespace:
     parser = argparse.ArgumentParser(
         description=(
             "Append a labeled markdown section containing a file or excerpt to a "
-            "target document, while enforcing the skill's fixed 100k-token hard budget."
+            "target document, while enforcing the skill's fixed 75k-token hard budget."
         )
     )
     parser.add_argument("source", type=Path, help="Source file to inline.")
@@ -104,19 +109,14 @@ def fail(message: str) -> "NoReturn":
 def normalize_span(start: int, end: int | None, total_lines: int) -> tuple[int, int]:
     if start < 1:
         fail("--start must be at least 1")
-    resolved_end = total_lines if end is None else end
-    if resolved_end < start:
-        fail("--end must be greater than or equal to --start")
     if start > total_lines:
         fail(
             f"--start {start} exceeds the source length of {total_lines} line"
             f"{'' if total_lines == 1 else 's'}"
         )
-    if resolved_end > total_lines:
-        fail(
-            f"--end {resolved_end} exceeds the source length of {total_lines} line"
-            f"{'' if total_lines == 1 else 's'}"
-        )
+    resolved_end = total_lines if end is None else min(end, total_lines)
+    if resolved_end < start:
+        fail("--end must be greater than or equal to --start")
     return start, resolved_end
 
 
@@ -146,6 +146,17 @@ def choose_fence(body: str) -> str:
     return "`" * max(3, longest_run + 1)
 
 
+@contextlib.contextmanager
+def hold_global_append_lock() -> Iterator[None]:
+    GLOBAL_APPEND_LOCK.parent.mkdir(parents=True, exist_ok=True)
+    with GLOBAL_APPEND_LOCK.open("a+", encoding="utf-8") as lock_file:
+        fcntl.flock(lock_file.fileno(), fcntl.LOCK_EX)
+        try:
+            yield
+        finally:
+            fcntl.flock(lock_file.fileno(), fcntl.LOCK_UN)
+
+
 def render_section(
     *,
     label: str,
@@ -199,29 +210,30 @@ def main() -> None:
         heading_level=args.heading_level,
     )
 
-    existing = ""
-    if target.exists():
-        if target.is_dir():
-            fail(f"target is a directory: {target}")
-        existing = target.read_text(encoding="utf-8", errors="replace")
-
-    separator = "\n\n" if existing else ""
-    rendered = f"{existing}{separator}{section}"
-
     encoding, encoding_label = load_encoding(args.model, args.encoding)
-    total_tokens = len(encoding.encode(rendered))
     section_tokens = len(encoding.encode(section))
-    existing_tokens = len(encoding.encode(existing))
-
-    if total_tokens > HARD_MAX_TOKENS:
-        fail(
-            "refusing append because the projected document would exceed the hard budget: "
-            f"{total_tokens} > {HARD_MAX_TOKENS} ({encoding_label}; existing={existing_tokens}; "
-            f"section={section_tokens})"
-        )
 
-    target.parent.mkdir(parents=True, exist_ok=True)
-    target.write_text(rendered, encoding="utf-8")
+    with hold_global_append_lock():
+        existing = ""
+        if target.exists():
+            if target.is_dir():
+                fail(f"target is a directory: {target}")
+            existing = target.read_text(encoding="utf-8", errors="replace")
+
+        separator = "\n\n" if existing else ""
+        rendered = f"{existing}{separator}{section}"
+        total_tokens = len(encoding.encode(rendered))
+        existing_tokens = len(encoding.encode(existing))
+
+        if total_tokens > HARD_MAX_TOKENS:
+            fail(
+                "refusing append because the projected document would exceed the hard budget: "
+                f"{total_tokens} > {HARD_MAX_TOKENS} ({encoding_label}; existing={existing_tokens}; "
+                f"section={section_tokens})"
+            )
+
+        target.parent.mkdir(parents=True, exist_ok=True)
+        target.write_text(rendered, encoding="utf-8")
 
     print(f"appended: {label}")
     print(f"source: {source}")