phase: 102_extensionless_filenames

All verification complete — every gate green, no defects found in previously completed work.

**Phase 102 final verification pass — report**

Verified (all three task files present in `complete/`; working-tree implementation matches D1–D5 design):
- `match_extension` choke point in `app/rag/importer.py` (walk + `formats` counter), `doc_format` name-token badge in `app/api/docs.py`, config/`.env.example` docs, fixture `tests/fixtures/extensionless_kb/`, integration + E2E suites — all present and correct
- Completion criteria: end-to-end sync (✓ integration + E2E), case matrix incl. `mydockerfile`/`Dockerfile.dev`/`.dockerfile` exclusions (✓ unit), `formats=dockerfile:1` not `unknown` (✓ log-line assertion), badge `dockerfile`/`containerfile` + `text` fallback + suffixed unchanged (✓ unit/integration/E2E), prune-on-token-removal (✓ `pruned==2`), suffixed-path rule byte-identical (✓ single-line swap, existing cases untouched)

Test / lint results (exact commands):
- `uv run pytest --cov=app --cov-report=term-missing` → 2084 passed, **99%** coverage (>90% gate)
- `uv run pytest tests/e2e/test_extensionless_import.py -v --no-cov` → 2 passed, isolated, DB up
- Regressions isolated: `test_import_documents` 3✓, `test_import_extensions_env` 2✓, `test_quadlet_jinja_import` 4✓, `test_document_viewer` 7✓, `test_kb_tree` 8✓
- `uv run ruff check .` → clean; `uv run pyright` → 0 errors, 0 warnings

Notable: commit intentionally not made (harness commits the phase); 102's task files already sit in `complete/`, overview stays in `todo/` for the harness.
Next pending phases: 98, 99, 103, 104, 105 (numeric next after 102: `103_suggestions_session_openers`).

app/rag/importer.py

@@ -19,7 +19,9 @@ the two-phase upsert:
 
 Scope (A9, revised 2026-08-21): any path containing a dot-prefixed
 component (hidden dirs — vendored caches like ``.esphome/.espressif/**`` —
-or hidden files) is skipped, plus the well-known exclusion list.
+or hidden files) is skipped, plus the well-known exclusion list. A token
+may also name extensionless files by their exact lowercased full filename
+(``Dockerfile`` under the ``dockerfile`` token — phase 102).
 
 ``prune=True`` deletes documents (of the imported sources only) whose files
 no longer exist **or no longer match the format filter** — this is how
@@ -158,6 +160,24 @@ def _ignore_for_root(
     return tuple(p for p in (normalize_ignore_path(e) for e in raw) if p)
 
 
+def match_extension(path: Path, extensions: frozenset[str]) -> str | None:
+    """The bare lowercased token *path* imports under, or ``None``.
+
+    1. Non-empty lowercased dotted suffix in *extensions* (the A9 rule —
+       ``kubernetes.md`` → ``md``).
+    2. No suffix: the lowercased FULL filename equals a bare token of
+       *extensions* (``Dockerfile`` → ``dockerfile``) — the phase-102
+       extensionless rule. Exact name only: ``mydockerfile`` never
+       matches the ``dockerfile`` token.
+    """
+    suffix = path.suffix.lower()
+    if suffix and suffix in extensions:
+        return suffix.lstrip(".")
+    if not suffix and path.name.lower() in {e.lstrip(".") for e in extensions}:
+        return path.name.lower()
+    return None
+
+
 def iter_importable_files(
     root: Path,
     extensions: frozenset[str],
@@ -187,7 +207,7 @@ def iter_importable_files(
             continue
         if ignore and is_ignored(rel.as_posix(), ignore):
             continue
-        if path.suffix.lower() not in extensions:
+        if match_extension(path, extensions) is None:
             continue
         files.append(path)
     return files
@@ -274,7 +294,13 @@ async def import_sources(
                 rel = path.relative_to(root).as_posix()
                 seen.add((source, rel))
                 summary.files += 1
-                ext = path.suffix.lower().lstrip(".") or "unknown"
+                # Phase 102: the matched bare token (``dockerfile`` for an
+                # extensionless ``Dockerfile``), never ``unknown`` — the
+                # file is in scope, so the walk matched it.
+                ext = (
+                    match_extension(path, llm.settings.import_extension_set)
+                    or "unknown"
+                )
                 summary.formats[ext] = summary.formats.get(ext, 0) + 1
                 if progress is not None:
                     # phase 64: report the file *before* indexing it — a