fix(audiobook): add AudiobookPlan.chapter_count so import doesn't 500 (#544)

POST /audiobook/import ended with `plan.chapter_count`, but AudiobookPlan
only exposed `char_count` (a property) and emitted `chapter_count` from
`to_dict()` — so the attribute access raised AttributeError, surfacing as
"500 Internal Server Error: 'AudiobookPlan' object has no attribute
'chapter_count'". The parse itself succeeded, so this hit every import
format (.txt/.md/.epub/.pdf), not just PDF.

Add a `chapter_count` property mirroring `char_count`, and have `to_dict()`
derive its key from it so the attribute and serialized key can't drift.
No API/schema/data change.

Tests: unit property test + a direct-handler /audiobook/import regression
(pdf/md/txt) that fails-before with the AttributeError.

Fixes #543

Co-authored-by: mergetest <test@local>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

backend/services/audiobook.py

@@ -65,10 +65,14 @@ class AudiobookPlan:
     def char_count(self) -> int:
         return sum(c.char_count for c in self.chapters)
 
+    @property
+    def chapter_count(self) -> int:
+        return len(self.chapters)
+
     def to_dict(self) -> dict:
         return {
             "chapters": [c.to_dict() for c in self.chapters],
-            "chapter_count": len(self.chapters),
+            "chapter_count": self.chapter_count,
             "char_count": self.char_count,
         }
 

tests/test_audiobook.py

@@ -76,6 +76,15 @@ def test_plan_to_dict_shape():
     assert d["chapters"][0]["spans"][0]["text"] == "Hi there."
 
 
+def test_plan_chapter_count_property():
+    # Regression for #543: the /audiobook/import endpoint reads plan.chapter_count
+    # directly (not via to_dict), so the attribute must exist and stay in lockstep
+    # with the serialized key.
+    plan = parse_audiobook_script("# A\nHi.\n# B\nBye.")
+    assert plan.chapter_count == 2
+    assert plan.chapter_count == plan.to_dict()["chapter_count"]
+
+
 # ── FFMETADATA ───────────────────────────────────────────────────────────────
 
 def test_ffmetadata_cumulative_offsets():

tests/test_longform_import.py

@@ -5,10 +5,12 @@ EPUB zip in memory (no fixture file, no new dep).
 """
 from __future__ import annotations
 
+import asyncio
 import io
 import zipfile
 
 import pytest
+from fastapi import UploadFile
 
 from services.longform_import import (
     chapterize_plaintext,
@@ -16,6 +18,7 @@ from services.longform_import import (
     pdf_to_chapter_script,
 )
 from services.audiobook import parse_audiobook_script
+from api.routers.audiobook import audiobook_import
 
 
 # ── PDF fixture builder ───────────────────────────────────────────────────
@@ -219,3 +222,28 @@ def test_pdf_too_many_pages_guard():
     data = _make_pdf(["Chapter 1", "Hi."])
     with pytest.raises(ValueError, match="too many pages"):
         pdf_to_chapter_script(data, max_pages=0)
+
+
+# ── import endpoint ────────────────────────────────────────────────────────
+# Calls the handler directly (no TestClient → no main+torch import), mirroring
+# tests/test_audiobook_cover.py.
+
+def _upload(name: str, data: bytes) -> UploadFile:
+    return UploadFile(io.BytesIO(data), filename=name)
+
+
+def test_import_endpoint_returns_chapter_count():
+    # Regression for #543: parsing succeeded but the endpoint then read
+    # plan.chapter_count, which didn't exist → 500 AttributeError. Covers the
+    # whole class — every import format hits this same return path.
+    pdf = _make_pdf(["Chapter 1", "Once upon a time.", "Chapter 2", "The end."])
+    for name, data in [
+        ("book.pdf", pdf),
+        ("book.md", b"# One\nhello\n\n# Two\nworld"),
+        ("book.txt", b"just a flat blob of narration with no headings"),
+    ]:
+        res = asyncio.run(audiobook_import(_upload(name, data)))
+        assert isinstance(res["chapters"], int) and res["chapters"] >= 1
+        assert res["text"].strip()
+    # The two-chapter inputs parse to exactly two chapters.
+    assert asyncio.run(audiobook_import(_upload("book.pdf", pdf)))["chapters"] == 2