fix: task 10 + review fix #1 — thread safety and sleep bug

Fix #1: Don't sleep after the final exhausted retry attempt in
_graph_request(). The sleep on the last iteration was pure overhead —
the loop exits immediately after, so the caller just waited an extra
backoff period for no reason. Guard with attempt < _MAX_RETRIES - 1.

Task 10: Add threading.Lock (_edits_lock) for all compound operations
on active_edits, which is accessed from both the UI thread and
background edit threads:
- __init__: declare self._edits_lock = threading.Lock()
- open_file: snapshot already_editing and at_limit under the lock,
  then release before showing blocking UI dialogs
- process_file: wrap initial dict assignment, waiting=True, the
  in-check+waiting=False, and in-check+del under the lock
- on_done_editing_clicked: lock the items() snapshot used to build
  waiting_files, preventing iteration over a dict being mutated

Add 8 new unit tests (1 for Fix #1 sleep count, 7 for Task 10 lock).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -41,6 +41,11 @@ coverage.xml
 
 # Local settings (keep your secrets safe)
 settings.json
+searchindex.json
 
 # Temporary files
 C:\Temp_SP\
+
+# Project tooling / AI assistant files
+tasks/
+.claude/

README.md

@@ -1,50 +1,89 @@
-# SharePoint Explorer
+# SharePoint Browser
 
-En moderne Python-baseret fil-browser til Microsoft SharePoint, designet til at omgå Windows' `MAX_PATH` (260 karakterer) begrænsning.
+En moderne Python-baseret fil-browser til Microsoft SharePoint, specielt designet til at omgå Windows' `MAX_PATH` (260 karakterer) begrænsning. Det opnås ved at integrere direkte med Microsoft Graph API ved hjælp af unikke ID'er og downloade/udtjekke filer til redigering via korte, midlertidige stier lokalt.
 
-## Funktioner
-- **Søg og Browse:** Naviger dynamisk gennem SharePoint sites, dokumentbiblioteker og mapper.
-- **Sikker Redigering:** Automatisk Check-out/Check-in håndtering via Microsoft Graph API.
-- **Explorer Vibes:** Moderne brugerflade med sortering (mapper øverst) og brødkrummesti (breadcrumb).
-- **Ingen Sti-begrænsning:** Arbejder med unikke ID'er og korte midlertidige stier for at undgå MAX_PATH fejl.
+## 🚀 Funktioner
 
-## Installation & Udvikling
+- **Ingen Sti-begrænsning (MAX_PATH):** Problemfri og pålidelig redigering uanset mappedybde i SharePoint.
+- **Sikker Redigering & Kollision-beskyttelse:** Automatisk Check-out/Check-in og intelligent overvågning af fil-låse lokalt.
+- **Professionel Brugerflade:** Bygget med `wxPython` (Native Windows UI) inklusiv indfødte OS-ikoner, data-drevet brødkrummesti (breadcrumbs) og lazy-loading af hierarkisk træstruktur for markant hurtigere navigation.
+- **Paginering & Stor-tenant understøttelse:** Alle Graph API-kald følger `@odata.nextLink` automatisk, så mapper og sites med hundredvis af elementer indlæses korrekt uden tab.
+- **Statuslinje med fremgangsmåler:** En integreret statusmåler (gauge) i statuslinjen giver visuelt feedback under alle netværksoperationer.
+- **First-Run Setup Wizard:** Automatisk konfigurationsguide ved første opstart, der opsamler Client ID og Tenant ID (kræver ingen forudgående manuel `settings.json`).
+- **Avanceret Søgning:** Hurtig global søgefunktion der bygger på et lokalt, trinvist opdateret indeks, samt understøttelse af "OG"-logik (AND logic).
+- **Fuld Fil- og Mappestyring:** Understøtter upload, sletning og omdøbning, samt visning af udvidet fil-metadata (filstørrelse, redigeringsdato).
+- **Multisprog:** Indbygget og brugerstyret understøttelse af både Dansk og Engelsk-grænseflade.
+- **Multi-File Editing:** Robust understøttelse for lokalt at redigere flere forskellige filer uafhængigt af hinanden i baggrunden uden at interface fryser.
+
+## ⚙️ Indstillinger
+
+Indstillingsdialogen er organiseret i faner:
+
+| Fane | Indhold |
+|------|---------|
+| **Konto** | Azure Client ID og Tenant ID |
+| **Stier** | Midlertidig downloadmappe og app-placering |
+| **Licens** | Licensnøgle og aktiveringsstatus |
+| **System** | Sprog og log-output til fejlfinding |
+| **Om** | Versionsinformation og kontaktoplysninger |
+
+## 🛠️ Teknologier
+
+- **Sprog:** Python 3.x
+- **GUI Framework:** wxPython
+- **Godkendelse:** MSAL (Microsoft Authentication Library)
+- **API Integration:** Microsoft Graph API via `requests`
+- **Fil-overvågning:** Polling via låse på lokalt filsystem
+
+## 📦 Installation & Opstart
 
 ### Forudsætninger
-- Python 3.x
-- Microsoft 365 licens (Business Standard eller højere anbefales)
+Sørg for, at du har Python installeret sammen med afhængighederne. Det anbefales at have en Microsoft 365-licens klar.
 
-### Setup
-1. Installer afhængigheder:
 ```bash
-   pip install customtkinter msal requests
+pip install wxPython msal requests
 ```
-2. Konfigurer `settings.json` med din `client_id` og `tenant_id`.
 
-### Kørsel
+### Kør applikationen
+Start op med:
 ```bash
 python sharepoint_browser.py
 ```
 
-## Kompilering til EXE
-For at pakke programmet til en enkelt selvstændig `.exe` fil:
+Ved første kørsel uden en konfiguration vil applikationen præsentere en Setup Wizard, hvor man nemt kan indtaste Microsoft-loginoplysningerne. Indtastningerne gemmes i en lokal `settings.json` fil.
+
+## 🏗️ Byg til EXE (Valgfrit)
+For at pakke programmet til en uafhængig, kørbar `.exe` fil til Windows bruges den medfølgende PyInstaller spec-fil:
+
 ```bash
 pip install pyinstaller
-python -m PyInstaller --noconsole --onefile --collect-all customtkinter --name "SharePoint Explorer" sharepoint_browser.py
+python -m PyInstaller "SharePoint Explorer.spec" --noconfirm
 ```
-Den færdige fil findes i mappen `dist/`. Husk at placere `settings.json` i samme mappe som `.exe` filen.
 
-## Konfiguration (`settings.json`)
-```json
-{
-    "client_id": "DIN_CLIENT_ID",
-    "tenant_id": "DIN_TENANT_ID",
-    "temp_dir": "C:\\Temp_SP"
-}
+Den færdige fil placeres i `dist/SharePoint Explorer.exe` med ikon indlejret.
 
-## Feature Request
- 1. Tilføj funktion til at gemme og administrere, flere tenants.
- 2. Debug log til at se hvad der sker i baggrunden.
- 3. Exteded log for 14 dage, som logger alle handlinger brugeren forateager sig i appen.
- 4. Licens styring, så man kan licencere programmet til kunder. Der skal være mulighed for 1 år, 3 år og unlimited. 
+## 🧩 Arkitektur & Workflow
+1. **Godkendelse:** Autentificerer brugeren via MSAL & MS Graph API.
+2. **Navigation:** Data hentes asynkront (lazy-loading) og chunked — de første resultater vises straks mens resten streames ind. Alt håndteres med ID'er i stedet for filstier, hvilket sikrer MAX_PATH-modstandsdygtighed.
+3. **Navigationskontekst:** Brødkrummestien er data-drevet; hvert segment gemmer det fulde navigationsobjekt, så klik på en forælder altid navigerer korrekt uden at gennemsøge træet.
+4. **Stale-result beskyttelse:** En navigations-tæller (`_nav_gen`) sikrer, at svar fra afbrudte netværkskald aldrig overskriver den aktive mappevisning.
+5. **Baggrundshåndtering af redigering:**
+    - Filer tjekkes ud (`Checkout`) direkte i SharePoint.
+    - Hentes ned til det lokale drev under korte stier, eks. `C:\Temp_SP\[MD5-Hash].[ext]`.
+    - Et baggrunds-thread overvåger det lokale program (fx Word) kontinuerligt via `os.rename()` tricket.
+    - Når filen lukkes, uploades ændringerne til SharePoint og modtager et `Checkin`.
+
+## 🧪 Tests
+En unit-test suite dækker de kritiske logik-komponenter:
+
+```bash
+python -m unittest tests.test_review_fixes -v
 ```
+
+Testene kører uden skærm/display og dækker: navigations-tæller, oversættelses-nøgler, URL-initialisering og signaturer.
+
+## 💡 Backlog / Kommende muligheder
+1. Integration for håndtering af flere tenants (lejemål)
+2. Et yderligere detaljeret log-system specielt til debugging af baggrundstråden.
+3. Udvidet aktivitetslog til sporing af handlinger for de seneste 14 dage.
+4. Styring af licenser til specifikke kunders varigheder (fx 1 år, 3 år, Lifetime).

requirements.txt

@@ -0,0 +1,4 @@
+wxPython>=4.2.1
+msal>=1.28.0
+requests>=2.31.0
+pyinstaller>=6.5.0

tests/test_review_fixes.py

@@ -0,0 +1,501 @@
+"""
+Unit tests for the code-review bug fixes applied to sharepoint_browser.py.
+
+Covers:
+  C1  - url=None prevents UnboundLocalError in _fetch_tree_children_bg
+  I1  - nav_gen guard in _finalize_list_loading discards stale results
+  I2  - System tab label derivation from STRINGS key
+  I3  - status_loading_items translation key present and formattable
+  C-1 - Refresh calls (nav_gen=None default) always apply their results
+  S-2 - nav_gen=None sentinel is safer than 0
+  S-1 - is_breadcrumb parameter removed from _navigate_to_item_data
+  S2  - Dead SITE branch removed from _append_list_items
+
+All tests run without a live display; wx is imported but no widgets are
+instantiated.
+"""
+
+import sys
+import os
+import inspect
+import unittest
+from unittest.mock import MagicMock, patch
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+import sharepoint_browser as sb
+
+
+# ---------------------------------------------------------------------------
+# I2 + I3: STRINGS dictionary
+# ---------------------------------------------------------------------------
+
+class TestStrings(unittest.TestCase):
+
+    def test_system_tab_label_da(self):
+        """I2: Danish settings_logging_group yields 'System' after split/strip."""
+        group = sb.STRINGS["da"]["settings_logging_group"]
+        self.assertEqual(group.split("/")[0].strip(), "System")
+
+    def test_system_tab_label_en(self):
+        """I2: English settings_logging_group yields 'System' after split/strip."""
+        group = sb.STRINGS["en"]["settings_logging_group"]
+        self.assertEqual(group.split("/")[0].strip(), "System")
+
+    def test_status_loading_items_present_da(self):
+        """I3: status_loading_items key exists in Danish STRINGS."""
+        self.assertIn("status_loading_items", sb.STRINGS["da"])
+
+    def test_status_loading_items_present_en(self):
+        """I3: status_loading_items key exists in English STRINGS."""
+        self.assertIn("status_loading_items", sb.STRINGS["en"])
+
+    def test_status_loading_items_format_da(self):
+        """I3: Danish template formats with named {count} argument."""
+        result = sb.STRINGS["da"]["status_loading_items"].format(count=42)
+        self.assertIn("42", result)
+
+    def test_status_loading_items_format_en(self):
+        """I3: English template formats with named {count} argument."""
+        result = sb.STRINGS["en"]["status_loading_items"].format(count=99)
+        self.assertIn("99", result)
+
+    def test_status_loading_items_da_uses_count_kwarg(self):
+        """I3: Danish template uses {count} placeholder (not positional)."""
+        template = sb.STRINGS["da"]["status_loading_items"]
+        self.assertIn("{count}", template)
+
+    def test_status_loading_items_en_uses_count_kwarg(self):
+        """I3: English template uses {count} placeholder (not positional)."""
+        template = sb.STRINGS["en"]["status_loading_items"]
+        self.assertIn("{count}", template)
+
+
+# ---------------------------------------------------------------------------
+# I1 + C-1 + S-2: nav_gen guard in _finalize_list_loading
+# ---------------------------------------------------------------------------
+
+class TestNavGenGuard(unittest.TestCase):
+    """
+    _finalize_list_loading(self, items_data, nav_gen=None)
+
+    Guard logic:
+      nav_gen is None  → always apply (refresh / unconstrained calls)
+      nav_gen == self._nav_gen → apply (matches current navigation)
+      nav_gen != self._nav_gen → discard (stale; user navigated away)
+    """
+
+    def _make_app(self, current_gen: int):
+        """Minimal mock that satisfies _finalize_list_loading's needs."""
+        app = MagicMock()
+        app._nav_gen = current_gen
+        # MagicMock is truthy by default so `if not self` passes
+        return app
+
+    # --- nav_gen=None cases (C-1 / S-2) ---
+
+    def test_none_gen_applies_when_nav_gen_is_1(self):
+        """C-1/S-2: nav_gen=None applies results regardless of _nav_gen."""
+        app = self._make_app(1)
+        items = [{"name": "a"}]
+        sb.SharePointApp._finalize_list_loading(app, items, nav_gen=None)
+        self.assertEqual(app.current_items, items)
+        app.apply_sorting.assert_called_once()
+
+    def test_none_gen_applies_when_nav_gen_is_high(self):
+        """C-1: nav_gen=None still applies when _nav_gen is large."""
+        app = self._make_app(99)
+        items = [{"name": "b"}]
+        sb.SharePointApp._finalize_list_loading(app, items, nav_gen=None)
+        self.assertEqual(app.current_items, items)
+
+    def test_default_gen_arg_applies(self):
+        """C-1: Omitting nav_gen entirely (default=None) always applies."""
+        app = self._make_app(5)
+        items = [{"name": "refresh"}]
+        sb.SharePointApp._finalize_list_loading(app, items)  # no nav_gen kwarg
+        self.assertEqual(app.current_items, items)
+        app.apply_sorting.assert_called_once()
+
+    # --- matching gen (I1, happy path) ---
+
+    def test_matching_gen_applies(self):
+        """I1: Results applied when nav_gen matches _nav_gen."""
+        app = self._make_app(3)
+        items = [{"name": "c"}]
+        sb.SharePointApp._finalize_list_loading(app, items, nav_gen=3)
+        self.assertEqual(app.current_items, items)
+        app.apply_sorting.assert_called_once()
+
+    # --- stale gen cases (I1) ---
+
+    def test_stale_gen_discards_results(self):
+        """I1: Results discarded when nav_gen < _nav_gen (user navigated away)."""
+        app = self._make_app(5)
+        sentinel = object()
+        app.current_items = sentinel
+        sb.SharePointApp._finalize_list_loading(app, [{"name": "old"}], nav_gen=2)
+        self.assertIs(app.current_items, sentinel,
+                      "current_items was overwritten by stale result")
+        app.apply_sorting.assert_not_called()
+
+    def test_future_gen_discards_results(self):
+        """I1: Results discarded when nav_gen > _nav_gen (shouldn't happen, but safe)."""
+        app = self._make_app(3)
+        sentinel = object()
+        app.current_items = sentinel
+        sb.SharePointApp._finalize_list_loading(app, [{"name": "future"}], nav_gen=99)
+        self.assertIs(app.current_items, sentinel)
+        app.apply_sorting.assert_not_called()
+
+    def test_gen_zero_still_discarded_when_nav_gen_nonzero(self):
+        """S-2: nav_gen=0 (old broken default) is now treated as a stale gen, not a pass."""
+        app = self._make_app(1)
+        sentinel = object()
+        app.current_items = sentinel
+        sb.SharePointApp._finalize_list_loading(app, [{"name": "zero"}], nav_gen=0)
+        self.assertIs(app.current_items, sentinel,
+                      "nav_gen=0 should be treated as stale, not as 'no constraint'")
+        app.apply_sorting.assert_not_called()
+
+
+# ---------------------------------------------------------------------------
+# C1: url=None initialization in _fetch_tree_children_bg
+# ---------------------------------------------------------------------------
+
+class TestUrlInitialization(unittest.TestCase):
+
+    def test_url_initialized_to_none_before_conditional(self):
+        """C1: _fetch_tree_children_bg initializes url=None before the if block."""
+        source = inspect.getsource(sb.SharePointApp._fetch_tree_children_bg)
+        # Find the line that sets url = None before the if data['type'] conditional
+        lines = source.splitlines()
+        url_none_idx = next(
+            (i for i, l in enumerate(lines) if "url = None" in l), None
+        )
+        site_if_idx = next(
+            (i for i, l in enumerate(lines)
+             if 'data[\'type\'] == "SITE"' in l or 'data["type"] == "SITE"' in l),
+            None
+        )
+        self.assertIsNotNone(url_none_idx,
+            "_fetch_tree_children_bg has no 'url = None' initializer")
+        self.assertIsNotNone(site_if_idx,
+            "_fetch_tree_children_bg has no SITE type conditional")
+        self.assertLess(url_none_idx, site_if_idx,
+            "'url = None' must appear before the if data['type'] block")
+
+
+# ---------------------------------------------------------------------------
+# S2: Dead SITE branch removed from _append_list_items
+# ---------------------------------------------------------------------------
+
+class TestDeadSiteBranch(unittest.TestCase):
+
+    def test_append_list_items_has_no_site_img_branch(self):
+        """S2: _append_list_items no longer contains the dead SITE image branch."""
+        source = inspect.getsource(sb.SharePointApp._append_list_items)
+        self.assertNotIn(
+            'item[\'type\'] == "SITE"',
+            source,
+            "_append_list_items still contains dead SITE branch"
+        )
+
+
+# ---------------------------------------------------------------------------
+# S-1: is_breadcrumb parameter removed from _navigate_to_item_data
+# ---------------------------------------------------------------------------
+
+class TestIsBreakcrumbRemoved(unittest.TestCase):
+
+    def test_no_is_breadcrumb_param(self):
+        """S-1: _navigate_to_item_data no longer has an is_breadcrumb parameter."""
+        sig = inspect.signature(sb.SharePointApp._navigate_to_item_data)
+        self.assertNotIn(
+            "is_breadcrumb", sig.parameters,
+            "_navigate_to_item_data still declares is_breadcrumb"
+        )
+
+    def test_tree_item_param_still_present(self):
+        """Regression: tree_item parameter was not accidentally removed."""
+        sig = inspect.signature(sb.SharePointApp._navigate_to_item_data)
+        self.assertIn("tree_item", sig.parameters)
+
+
+# ---------------------------------------------------------------------------
+# Task 7: bare except → except Exception, print → logger, basename sanitization
+# ---------------------------------------------------------------------------
+
+class TestTask7BareExcept(unittest.TestCase):
+    """Verify that bare except: clauses have been replaced with except Exception:."""
+
+    def _get_source_lines(self):
+        return inspect.getsource(sb).splitlines()
+
+    def test_no_bare_except_in_load_settings(self):
+        """7a: load_settings() uses except Exception, not bare except."""
+        source = inspect.getsource(sb.load_settings)
+        self.assertNotIn("except:", source,
+            "load_settings still has a bare except:")
+
+    def test_no_bare_except_in_get_txt(self):
+        """7a: get_txt() uses except Exception, not bare except."""
+        source = inspect.getsource(sb.SharePointApp.get_txt)
+        self.assertNotIn("except:", source,
+            "get_txt still has a bare except:")
+
+    def test_no_bare_except_in_get_icon_idx(self):
+        """7a: get_icon_idx_for_file() uses except Exception, not bare except."""
+        source = inspect.getsource(sb.SharePointApp.get_icon_idx_for_file)
+        self.assertNotIn("except:", source,
+            "get_icon_idx_for_file still has a bare except:")
+
+    def test_no_bare_except_in_process_file(self):
+        """7a: process_file() cleanup block uses except Exception, not bare except."""
+        source = inspect.getsource(sb.SharePointApp.process_file)
+        self.assertNotIn("except:", source,
+            "process_file still has a bare except: in cleanup block")
+
+    def test_no_print_in_msal_init(self):
+        """7b: MSAL init error uses logger, not print()."""
+        source = inspect.getsource(sb.SharePointApp.__init__)
+        self.assertNotIn('print(f"MSAL Init Error', source,
+            "__init__ still uses print() for MSAL Init Error")
+
+    def test_no_print_in_ensure_valid_token(self):
+        """7b: ensure_valid_token() uses logger, not print()."""
+        source = inspect.getsource(sb.SharePointApp.ensure_valid_token)
+        self.assertNotIn('print(f"Token refresh error', source,
+            "ensure_valid_token still uses print() for token error")
+
+    def test_basename_in_download_folder_recursive(self):
+        """7c: _download_folder_recursive_sync uses os.path.basename on item name."""
+        source = inspect.getsource(sb.SharePointApp._download_folder_recursive_sync)
+        self.assertIn("os.path.basename", source,
+            "_download_folder_recursive_sync does not sanitize item['name'] with basename")
+
+    def test_basename_in_on_download_clicked(self):
+        """7c: on_download_clicked uses os.path.basename when building dest_path for folders."""
+        source = inspect.getsource(sb.SharePointApp.on_download_clicked)
+        self.assertIn("os.path.basename", source,
+            "on_download_clicked does not sanitize item['name'] with basename for folder downloads")
+
+
+# ---------------------------------------------------------------------------
+# Task 8: all requests.* calls must carry a timeout= parameter
+# ---------------------------------------------------------------------------
+
+class TestNetworkTimeouts(unittest.TestCase):
+    """
+    Every requests.get/post/put/patch/delete call must include timeout=
+    so that background threads cannot hang indefinitely on a stalled network.
+    """
+
+    def _calls_missing_timeout(self):
+        """
+        Return a list of (line_number, line_text) for every requests.*()
+        call in the source file that is missing a timeout= argument.
+
+        Strategy: single-line calls are the norm in this codebase.  We look
+        for lines that contain 'requests.METHOD(' and do NOT also contain
+        'timeout='.  Lines that contain 'timeout=' anywhere on the same line
+        are considered compliant.
+        """
+        import re
+        src_path = os.path.join(
+            os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
+            "sharepoint_browser.py"
+        )
+        # Matches real call sites: assignment or standalone call (not docstrings)
+        pattern = re.compile(
+            r'(=\s*|^\s*)requests\.(get|post|put|patch|delete)\('
+        )
+        missing = []
+        with open(src_path, encoding='utf-8') as fh:
+            for lineno, line in enumerate(fh, 1):
+                stripped = line.lstrip()
+                # Skip comment lines and docstring prose (lines that are plain text)
+                if stripped.startswith('#'):
+                    continue
+                if pattern.search(line) and 'timeout=' not in line:
+                    missing.append((lineno, line.rstrip()))
+        return missing
+
+    def test_all_requests_calls_have_timeout(self):
+        """Task 8: No requests.* call is missing a timeout= parameter."""
+        missing = self._calls_missing_timeout()
+        if missing:
+            details = "\n".join(f"  line {n}: {txt}" for n, txt in missing)
+            self.fail(
+                f"{len(missing)} requests call(s) are missing timeout=:\n{details}"
+            )
+
+
+# ---------------------------------------------------------------------------
+# Task 9: _graph_request helper — retry on 429/503 with Retry-After support
+# ---------------------------------------------------------------------------
+
+class TestGraphRequest(unittest.TestCase):
+    """Unit tests for the _graph_request() module-level helper."""
+
+    def test_helper_exists(self):
+        """Task 9: _graph_request function is defined at module level."""
+        self.assertTrue(
+            callable(getattr(sb, "_graph_request", None)),
+            "_graph_request is not defined in sharepoint_browser"
+        )
+
+    def test_success_on_first_attempt(self):
+        """Task 9: Returns immediately when first response is 200."""
+        mock_resp = MagicMock()
+        mock_resp.status_code = 200
+        with patch("sharepoint_browser.requests.request", return_value=mock_resp) as mock_req:
+            result = sb._graph_request("GET", "https://example.com/", headers={})
+        self.assertEqual(result.status_code, 200)
+        self.assertEqual(mock_req.call_count, 1)
+
+    def test_retries_on_429(self):
+        """Task 9: Retries when response is 429 (rate limited)."""
+        responses = [
+            MagicMock(status_code=429, headers={"Retry-After": "0"}),
+            MagicMock(status_code=429, headers={"Retry-After": "0"}),
+            MagicMock(status_code=200, headers={}),
+        ]
+        with patch("sharepoint_browser.requests.request", side_effect=responses) as mock_req:
+            with patch("sharepoint_browser.time.sleep"):
+                result = sb._graph_request("GET", "https://example.com/", headers={})
+        self.assertEqual(result.status_code, 200)
+        self.assertEqual(mock_req.call_count, 3)
+
+    def test_retries_on_503(self):
+        """Task 9: Retries when response is 503 (service unavailable)."""
+        responses = [
+            MagicMock(status_code=503, headers={}),
+            MagicMock(status_code=200, headers={}),
+        ]
+        with patch("sharepoint_browser.requests.request", side_effect=responses) as mock_req:
+            with patch("sharepoint_browser.time.sleep"):
+                result = sb._graph_request("POST", "https://example.com/", headers={})
+        self.assertEqual(result.status_code, 200)
+        self.assertEqual(mock_req.call_count, 2)
+
+    def test_returns_last_response_after_max_retries(self):
+        """Task 9: Returns last 429 response when all retries are exhausted."""
+        resp_429 = MagicMock(status_code=429, headers={"Retry-After": "0"})
+        responses = [resp_429] * sb._MAX_RETRIES
+        with patch("sharepoint_browser.requests.request", side_effect=responses):
+            with patch("sharepoint_browser.time.sleep"):
+                result = sb._graph_request("GET", "https://example.com/", headers={})
+        self.assertEqual(result.status_code, 429)
+
+    def test_respects_retry_after_header(self):
+        """Task 9: sleep() is called with the Retry-After value from the response."""
+        responses = [
+            MagicMock(status_code=429, headers={"Retry-After": "5"}),
+            MagicMock(status_code=200, headers={}),
+        ]
+        with patch("sharepoint_browser.requests.request", side_effect=responses):
+            with patch("sharepoint_browser.time.sleep") as mock_sleep:
+                sb._graph_request("GET", "https://example.com/", headers={})
+        mock_sleep.assert_called_once_with(5)
+
+    def test_default_timeout_injected(self):
+        """Task 9: timeout=30 is injected when caller does not provide one."""
+        mock_resp = MagicMock(status_code=200, headers={})
+        with patch("sharepoint_browser.requests.request", return_value=mock_resp) as mock_req:
+            sb._graph_request("GET", "https://example.com/", headers={})
+        _, kwargs = mock_req.call_args
+        self.assertEqual(kwargs.get("timeout"), 30)
+
+    def test_caller_timeout_not_overridden(self):
+        """Task 9: Explicit timeout from caller is not overwritten by the helper."""
+        mock_resp = MagicMock(status_code=200, headers={})
+        with patch("sharepoint_browser.requests.request", return_value=mock_resp) as mock_req:
+            sb._graph_request("GET", "https://example.com/", headers={}, timeout=60)
+        _, kwargs = mock_req.call_args
+        self.assertEqual(kwargs.get("timeout"), 60)
+
+    def test_max_retries_constant_exists(self):
+        """Task 9: _MAX_RETRIES constant is defined."""
+        self.assertTrue(
+            hasattr(sb, "_MAX_RETRIES"),
+            "_MAX_RETRIES constant not found in sharepoint_browser"
+        )
+
+    def test_no_sleep_after_final_retry(self):
+        """Fix #1: sleep() is NOT called after the last exhausted attempt."""
+        resp_429 = MagicMock(status_code=429, headers={"Retry-After": "0"})
+        responses = [resp_429] * sb._MAX_RETRIES
+        with patch("sharepoint_browser.requests.request", side_effect=responses):
+            with patch("sharepoint_browser.time.sleep") as mock_sleep:
+                sb._graph_request("GET", "https://example.com/", headers={})
+        # sleep should be called for the first N-1 failures, NOT the last one
+        self.assertEqual(
+            mock_sleep.call_count,
+            sb._MAX_RETRIES - 1,
+            f"sleep() called {mock_sleep.call_count} times; expected {sb._MAX_RETRIES - 1} "
+            f"(no sleep after the final failed attempt)"
+        )
+
+
+# ---------------------------------------------------------------------------
+# Task 10: threading.Lock for active_edits compound operations
+# ---------------------------------------------------------------------------
+
+class TestActiveEditsLock(unittest.TestCase):
+    """Verify that _edits_lock exists and guards all compound active_edits operations."""
+
+    def test_edits_lock_declared_in_init(self):
+        """Task 10: SharePointApp.__init__ creates self._edits_lock."""
+        source = inspect.getsource(sb.SharePointApp.__init__)
+        self.assertIn("_edits_lock", source,
+            "__init__ does not declare _edits_lock")
+
+    def test_edits_lock_is_threading_lock(self):
+        """Task 10: _edits_lock initialisation uses threading.Lock()."""
+        source = inspect.getsource(sb.SharePointApp.__init__)
+        self.assertIn("threading.Lock()", source,
+            "__init__ does not initialise _edits_lock with threading.Lock()")
+
+    def test_open_file_uses_lock(self):
+        """Task 10: open_file() acquires _edits_lock before checking active_edits."""
+        source = inspect.getsource(sb.SharePointApp.open_file)
+        self.assertIn("_edits_lock", source,
+            "open_file does not use _edits_lock")
+
+    def test_process_file_uses_lock(self):
+        """Task 10: process_file() acquires _edits_lock when writing active_edits."""
+        source = inspect.getsource(sb.SharePointApp.process_file)
+        self.assertIn("_edits_lock", source,
+            "process_file does not use _edits_lock")
+
+    def test_process_file_lock_on_initial_assign(self):
+        """Task 10: active_edits[item_id] = ... assignment is inside a lock block."""
+        source = inspect.getsource(sb.SharePointApp.process_file)
+        # Check lock wraps the initial dict assignment
+        lock_idx = source.find("_edits_lock")
+        assign_idx = source.find('self.active_edits[item_id] = ')
+        self.assertGreater(assign_idx, 0,
+            "active_edits assignment not found in process_file")
+        # The lock must appear before the assignment
+        self.assertLess(lock_idx, assign_idx,
+            "_edits_lock must appear before the active_edits assignment in process_file")
+
+    def test_process_file_lock_on_delete(self):
+        """Task 10: del active_edits[item_id] is inside a lock block in process_file."""
+        source = inspect.getsource(sb.SharePointApp.process_file)
+        self.assertIn("del self.active_edits[item_id]", source,
+            "del active_edits[item_id] not found in process_file")
+        # Count lock usages — there should be at least 2
+        lock_count = source.count("_edits_lock")
+        self.assertGreaterEqual(lock_count, 2,
+            f"Expected at least 2 uses of _edits_lock in process_file, found {lock_count}")
+
+    def test_on_done_editing_uses_lock(self):
+        """Task 10: on_done_editing_clicked acquires lock for active_edits iteration."""
+        source = inspect.getsource(sb.SharePointApp.on_done_editing_clicked)
+        self.assertIn("_edits_lock", source,
+            "on_done_editing_clicked does not use _edits_lock")
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)