Add Debian BTS source for bugs filed and owned

New `bts` subcommand backed by python-debianbts (bugs.debian.org SOAP):

- Identify by email address: get_bugs(submitter=...) for bugs filed,
  get_bugs(owner=...) for bugs owned
- Filed filtered on creation date, owned on log_modified; status
  lookups capped at 500 bugs per collect
- Per-query failures degrade to warnings like other sources

src/weekly_activity/cli.py

@@ -9,6 +9,7 @@ from datetime import UTC, datetime
 
 from weekly_activity.model import last_week_window
 from weekly_activity.report import format_report
+from weekly_activity.sources.debian_bts import DebianBtsSource
 from weekly_activity.sources.github import GitHubSource
 from weekly_activity.sources.gitlab import GitLabSource
 from weekly_activity.sources.launchpad import LaunchpadSource
@@ -68,6 +69,9 @@ def parse_args(argv: Sequence[str] | None = None) -> argparse.Namespace:
         help="Env var holding the API token (see README for discovery order).",
     )
 
+    bts = subparsers.add_parser("bts", parents=[base], help="Debian Bug Tracking System activity.")
+    bts.add_argument("username", help="Email address used on Debian bugs (submitter/owner).")
+
     return parser.parse_args(argv)
 
 
@@ -106,6 +110,8 @@ def main() -> None:
         source = GitHubSource(token=args.token)
     elif args.source == "gitlab":
         source = GitLabSource(url=args.url, token=args.token, token_env=args.token_env)
+    elif args.source == "bts":
+        source = DebianBtsSource()
     else:
         raise SystemExit(f"error: unknown source {args.source!r}")
 

src/weekly_activity/sources/debian_bts.py

@@ -0,0 +1,95 @@
+"""Debian Bug Tracking System activity source — bugs filed and owned.
+
+Queries bugs.debian.org over SOAP via python-debianbts. Identification is
+by email address (the one used on Debian bugs), not a username.
+"""
+
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Any
+
+import debianbts
+
+from weekly_activity.model import ActivityReport, Section
+
+
+def _to_naive_utc(value: object) -> datetime | None:
+    """Normalize a datetime (naive or aware) to naive UTC."""
+    if not isinstance(value, datetime):
+        return None
+    if value.tzinfo is not None:
+        return value.astimezone(value.tzinfo).replace(tzinfo=None)
+    return value
+
+
+def _fmt_date(dt: datetime | None) -> str:
+    return dt.strftime("%Y-%m-%d") if dt is not None else "—"
+
+
+class DebianBtsSource:
+    """Debian BTS activity source implementing ActivitySource."""
+
+    name = "debian-bts"
+
+    MAX_BUGS = 500  # safety cap on per-collect status lookups
+
+    def __init__(self, *, server: str = "https://bugs.debian.org") -> None:
+        self._server = server.rstrip("/")
+
+    def collect(self, username: str, since: datetime, until: datetime) -> ActivityReport:
+        warnings: list[str] = []
+
+        def safe(label: str, fn: Any) -> Any:
+            try:
+                return fn()
+            except Exception as exc:  # noqa: BLE001 - degrade section, keep report
+                warnings.append(f"{label}: {type(exc).__name__}: {exc}")
+                return None
+
+        # --- Bugs filed / owned ---
+        filed_nums = safe("bugs filed", lambda: debianbts.get_bugs(submitter=username)) or []
+        owned_nums = safe("bugs owned", lambda: debianbts.get_bugs(owner=username)) or []
+        filed_set = set(filed_nums)
+        owned_set = set(owned_nums)
+
+        all_nums = sorted(filed_set | owned_set)[: self.MAX_BUGS]
+        reports: list[Any] = []
+        if all_nums:
+            result = safe("bug status", lambda: debianbts.get_status(all_nums))
+            if result is not None:
+                reports = list(result)
+
+        filed_entries: list[tuple[datetime | None, str]] = []
+        owned_entries: list[tuple[datetime | None, str]] = []
+        for report in reports:
+            num = getattr(report, "bug_num", None)
+            subject = getattr(report, "subject", None) or "(untitled)"
+            package = getattr(report, "package", None) or "(no package)"
+            severity = getattr(report, "severity", None) or "unknown"
+            pending = getattr(report, "pending", None) or "unknown"
+            created = _to_naive_utc(getattr(report, "date", None))
+            modified = _to_naive_utc(getattr(report, "log_modified", None))
+            base = f"  [#{num}] {subject}\n    {package} · {pending} · severity {severity}"
+            url = f"{self._server}/{num}"
+            if num in filed_set and created is not None and since <= created < until:
+                filed_entries.append((created, f"{base} · created {_fmt_date(created)}\n    {url}"))
+            if num in owned_set and modified is not None and since <= modified < until:
+                owned_entries.append(
+                    (modified, f"{base} · last modified {_fmt_date(modified)}\n    {url}")
+                )
+
+        filed_entries.sort(key=lambda x: x[0] or datetime.min, reverse=True)
+        owned_entries.sort(key=lambda x: x[0] or datetime.min, reverse=True)
+
+        return ActivityReport(
+            source=self.name,
+            username=username,
+            since=since,
+            until=until,
+            sections=[
+                Section("Bugs filed", [entry for _, entry in filed_entries]),
+                Section("Bugs owned, updated", [entry for _, entry in owned_entries]),
+            ],
+            warnings=warnings,
+        )