diff --git a/graphify/__main__.py b/graphify/__main__.py
index c5151b8..b424327 100644
--- a/graphify/__main__.py
+++ b/graphify/__main__.py
@@ -597,6 +597,8 @@ def _run_cli() -> None:
         print("                            proxy, gateways): set ANTHROPIC_BASE_URL and ANTHROPIC_MODEL")
         print("    --model M               override backend default model")
         print("    --mode deep             aggressive INFERRED-edge semantic extraction")
+        print("    --force                 full re-scan and re-dispatch: skip the incremental")
+        print("                            manifest gate and semantic cache reads (env: GRAPHIFY_FORCE=1)")
         print("    --max-workers N         AST extraction subprocess count (default: cpu_count)")
         print("    --token-budget N        per-chunk token cap for semantic extraction (default: 60000)")
         print("    --max-concurrency N     parallel semantic chunks in flight (default: 4; set 1 for local LLMs)")
diff --git a/graphify/cache.py b/graphify/cache.py
index 3055db7..15795d4 100644
--- a/graphify/cache.py
+++ b/graphify/cache.py
@@ -90,7 +90,8 @@ def _body_content(content: bytes) -> bytes:
 # size+mtime_ns are unchanged — same trade-off as make(1).
 # Correctness risks: `touch` causes a harmless extra re-hash; same-size edits
 # within NFS second-resolution mtime have a 1-second window (same as make).
-# Use `graphify extract --force` to bypass when needed.
+# `graphify extract --force` / `graphify update --force` (or GRAPHIFY_FORCE=1)
+# skip the cache reads and re-dispatch everything when needed (#1894).
 _stat_index: dict[str, dict] = {}
 _stat_index_root: Path | None = None
 _stat_index_dirty: bool = False
@@ -340,13 +341,15 @@ def _absolutize_source_files_in(payload: dict, root: Path) -> None:
 def cache_dir(root: Path = Path("."), kind: str = "ast") -> Path:
     """Returns the cache directory for ``kind`` - creates it if needed.
 
-    kind is "ast" or "semantic". Separate subdirectories prevent semantic cache
+    kind is "ast", "semantic", or a mode-namespaced semantic kind such as
+    "semantic-deep" (#1894). Separate subdirectories prevent semantic cache
     entries from overwriting AST cache entries for the same source_file (#582).
 
     AST entries live in graphify-out/cache/ast/v{version}/ — namespaced by
     graphify version because they depend on extractor code, not just file
     contents. Semantic entries live unversioned in graphify-out/cache/semantic/
-    (re-extraction costs LLM calls).
+    (re-extraction costs LLM calls); deep-mode entries live beside them in
+    graphify-out/cache/semantic-deep/.
     """
     _out = Path(_GRAPHIFY_OUT)
     base = _out if _out.is_absolute() else Path(root).resolve() / _out
@@ -467,8 +470,10 @@ def cached_files(root: Path = Path(".")) -> set[str]:
     # Legacy flat entries
     if base.is_dir():
         hashes.update(p.stem for p in base.glob("*.json"))
-    # Namespaced entries (ast/ recursively, covering per-version subdirs)
-    for kind, pattern in (("ast", "**/*.json"), ("semantic", "*.json")):
+    # Namespaced entries (ast/ recursively, covering per-version subdirs;
+    # semantic-deep/ holds --mode deep entries, #1894)
+    for kind, pattern in (("ast", "**/*.json"), ("semantic", "*.json"),
+                          ("semantic-deep", "*.json")):
         d = base / kind
         if d.is_dir():
             hashes.update(p.stem for p in d.glob(pattern))
@@ -476,14 +481,17 @@ def cached_files(root: Path = Path(".")) -> set[str]:
 
 
 def clear_cache(root: Path = Path(".")) -> None:
-    """Delete all cache entries (ast/, semantic/, and legacy flat entries)."""
+    """Delete all cache entries (ast/, semantic/, semantic-deep/, and legacy
+    flat entries)."""
     base = Path(root).resolve() / _GRAPHIFY_OUT / "cache"
     # Legacy flat entries
     if base.is_dir():
         for f in base.glob("*.json"):
             f.unlink()
-    # Namespaced entries (ast/ recursively, covering per-version subdirs)
-    for kind, pattern in (("ast", "**/*.json"), ("semantic", "*.json")):
+    # Namespaced entries (ast/ recursively, covering per-version subdirs;
+    # semantic-deep/ holds --mode deep entries, #1894)
+    for kind, pattern in (("ast", "**/*.json"), ("semantic", "*.json"),
+                          ("semantic-deep", "*.json")):
         d = base / kind
         if d.is_dir():
             for f in d.glob(pattern):
@@ -500,11 +508,16 @@ def prune_semantic_cache(root: Path, live_hashes: set[str]) -> int:
     AST version-cleanup, so every content change or file deletion leaves a
     permanent orphan entry that accumulates unbounded.
 
-    This sweeps ``cache/semantic/*.json`` and deletes any entry whose stem (the
-    content hash) is not in ``live_hashes`` — the hashes of the current live
-    document set. ``*.tmp`` atomic-write temporaries are skipped, and only this
-    directory is touched (never ``cache/ast/**`` or anything else). The
-    unversioned design is preserved: we prune by liveness, not by version.
+    This sweeps ``cache/semantic/*.json`` AND ``cache/semantic-deep/*.json``
+    (the ``--mode deep`` namespace, #1894) and deletes any entry whose stem
+    (the content hash) is not in ``live_hashes`` — the hashes of the current
+    live document set. Both namespaces are pruned against the SAME live set:
+    liveness is content-based and mode-independent, so a hash that is live for
+    one namespace is live for both. Skipping the deep namespace would re-grow
+    the unbounded-orphan problem this function fixed (#1527). ``*.tmp``
+    atomic-write temporaries are skipped, and only these directories are
+    touched (never ``cache/ast/**`` or anything else). The unversioned design
+    is preserved: we prune by liveness, not by version.
 
     Best-effort, mirroring :func:`_cleanup_stale_ast_entries`: each unlink is
     wrapped in ``try/except OSError`` and a failure is ignored. The worst-case
@@ -513,30 +526,40 @@ def prune_semantic_cache(root: Path, live_hashes: set[str]) -> int:
     """
     _out = Path(_GRAPHIFY_OUT)
     base = _out if _out.is_absolute() else Path(root).resolve() / _out
-    semantic_dir = base / "cache" / "semantic"
-    if not semantic_dir.is_dir():
-        return 0
     pruned = 0
-    for entry in semantic_dir.glob("*.json"):
-        if entry.stem in live_hashes:
+    for kind in ("semantic", "semantic-deep"):
+        semantic_dir = base / "cache" / kind
+        if not semantic_dir.is_dir():
             continue
-        try:
-            entry.unlink()
-            pruned += 1
-        except OSError:
-            pass
+        for entry in semantic_dir.glob("*.json"):
+            if entry.stem in live_hashes:
+                continue
+            try:
+                entry.unlink()
+                pruned += 1
+            except OSError:
+                pass
     return pruned
 
 
 def check_semantic_cache(
     files: list[str],
     root: Path = Path("."),
+    mode: str | None = None,
 ) -> tuple[list[dict], list[dict], list[dict], list[str]]:
     """Check semantic extraction cache for a list of absolute file paths.
 
     Returns (cached_nodes, cached_edges, cached_hyperedges, uncached_files).
     Uncached files need Claude extraction; cached files are merged directly.
+
+    ``mode`` selects the cache namespace: ``None`` (the default) reads
+    ``cache/semantic/`` — byte-identical to the historical behavior, so
+    existing callers that omit it (including older installed skill flows)
+    are unaffected. A non-None mode (e.g. ``"deep"``) reads
+    ``cache/semantic-{mode}/`` instead, so deep-mode results never shadow
+    (or get shadowed by) standard-mode entries for the same content (#1894).
     """
+    kind = "semantic" if mode is None else f"semantic-{mode}"
     cached_nodes: list[dict] = []
     cached_edges: list[dict] = []
     cached_hyperedges: list[dict] = []
@@ -546,7 +569,7 @@ def check_semantic_cache(
         p = Path(fpath)
         if not p.is_absolute():
             p = Path(root) / p
-        result = load_cached(p, root, kind="semantic")
+        result = load_cached(p, root, kind=kind)
         if result is not None:
             cached_nodes.extend(result.get("nodes", []))
             cached_edges.extend(result.get("edges", []))
@@ -564,6 +587,7 @@ def save_semantic_cache(
     root: Path = Path("."),
     merge_existing: bool = False,
     allowed_source_files: Iterable[str | Path] | None = None,
+    mode: str | None = None,
 ) -> int:
     """Save semantic extraction results to cache, keyed by source_file.
 
@@ -571,6 +595,13 @@ def save_semantic_cache(
     under cache/semantic/ (separate from AST entries in cache/ast/) to prevent
     hash-key collisions (#582).
 
+    ``mode`` selects the cache namespace, mirroring
+    :func:`check_semantic_cache`: ``None`` (the default) writes
+    ``cache/semantic/`` — byte-identical to the historical behavior for
+    existing callers that omit it — while a non-None mode (e.g. ``"deep"``)
+    writes ``cache/semantic-{mode}/`` so richer deep-mode results never
+    overwrite standard-mode entries and vice versa (#1894).
+
     When ``merge_existing`` is True, any already-cached entry for a file is
     unioned with the new results before saving instead of being overwritten.
     This lets callers checkpoint incrementally (e.g. once per chunk) without
@@ -584,6 +615,7 @@ def save_semantic_cache(
     """
     from collections import defaultdict
 
+    kind = "semantic" if mode is None else f"semantic-{mode}"
     by_file: dict[str, dict] = defaultdict(lambda: {"nodes": [], "edges": [], "hyperedges": []})
     for n in nodes:
         src = n.get("source_file", "")
@@ -684,13 +716,13 @@ def save_semantic_cache(
                 )
                 continue
             if merge_existing:
-                prev = load_cached(p, root, kind="semantic")
+                prev = load_cached(p, root, kind=kind)
                 if prev:
                     result = {
                         "nodes": (prev.get("nodes", []) or []) + result["nodes"],
                         "edges": (prev.get("edges", []) or []) + result["edges"],
                         "hyperedges": (prev.get("hyperedges", []) or []) + result["hyperedges"],
                     }
-            save_cached(p, result, root, kind="semantic")
+            save_cached(p, result, root, kind=kind)
             saved += 1
     return saved
diff --git a/graphify/cli.py b/graphify/cli.py
index 5061d85..f2ae1da 100644
--- a/graphify/cli.py
+++ b/graphify/cli.py
@@ -2138,6 +2138,9 @@ def dispatch_command(cmd: str) -> None:
         cli_exclude_hubs: float | None = None
         cli_excludes: list[str] = []
         cli_timing: bool = False
+        # --force parity with `graphify update`: the flag or GRAPHIFY_FORCE=1
+        # disables the incremental gate and skips semantic-cache reads (#1894).
+        force = os.environ.get("GRAPHIFY_FORCE", "").lower() in ("1", "true", "yes")
 
         def _parse_int(name: str, raw: str) -> int:
             try:
@@ -2228,6 +2231,8 @@ def dispatch_command(cmd: str) -> None:
             elif a == "--cargo":
                 cli_cargo = True
                 i += 1
+            elif a == "--force":
+                force = True; i += 1
             elif a == "--timing":
                 cli_timing = True; i += 1
             else:
@@ -2277,6 +2282,11 @@ def dispatch_command(cmd: str) -> None:
         manifest_path = graphify_out / "manifest.json"
         existing_graph_path = graphify_out / "graph.json"
         incremental_mode = manifest_path.exists() and existing_graph_path.exists() if has_path else False
+        # --force: full scan, not the manifest-gated incremental diff — a warm
+        # unchanged tree would otherwise dispatch zero files (#1894).
+        incremental_mode = incremental_mode and not force
+        if force:
+            print("[graphify extract] --force: full re-scan, semantic cache reads skipped")
 
         if not has_path:
             code_files = []
@@ -2343,6 +2353,30 @@ def dispatch_command(cmd: str) -> None:
             doc_files = []
             paper_files = []
             image_files = []
+        if deep_mode and incremental_mode and not code_only:
+            # Deep mode reads/writes its own cache namespace
+            # (cache/semantic-deep/), so the manifest's changed-file gate is
+            # not a valid proxy for deep coverage: over a warm unchanged tree
+            # it dispatches zero files and `--mode deep` silently no-ops
+            # (#1894). Widen the semantic pass to the FULL live
+            # doc/paper/image set (``files_by_type`` from detect_incremental,
+            # which already excludes excluded files) and let the
+            # mode-namespaced cache decide hits/misses — the first deep run
+            # re-dispatches everything (deep namespace cold), later deep runs
+            # hit the deep cache.
+            _deep_all = [
+                Path(p)
+                for _ftype in ("document", "paper", "image")
+                for p in files_by_type.get(_ftype, [])
+            ]
+            if len(_deep_all) != len(semantic_files):
+                print(
+                    f"[graphify extract] deep mode: widening semantic pass from "
+                    f"{len(semantic_files)} changed to {len(_deep_all)} live "
+                    f"doc/paper/image file(s); the deep semantic cache decides "
+                    f"what is re-extracted"
+                )
+            semantic_files = _deep_all
         if incremental_mode:
             # Excluded-but-alive files are reported separately from deletions
             # (#1908): they still exist on disk, the scan just stopped
@@ -2495,11 +2529,21 @@ def dispatch_command(cmd: str) -> None:
         }
         sem_cache_hits = 0
         sem_cache_misses = 0
+        # Deep mode uses its own namespace (cache/semantic-deep/) so deep and
+        # standard results for the same content never shadow each other (#1894).
+        sem_cache_mode = "deep" if deep_mode else None
         if semantic_files:
             sem_paths_str = [str(p) for p in semantic_files]
-            cached_nodes, cached_edges, cached_hyperedges, uncached_paths = (
-                _check_semantic_cache(sem_paths_str, root=out_root)
-            )
+            if force:
+                # --force: skip the cache READ so every semantic file is
+                # re-dispatched; the save below still runs so the fresh
+                # results replace the stale entries.
+                cached_nodes, cached_edges, cached_hyperedges = [], [], []
+                uncached_paths = list(sem_paths_str)
+            else:
+                cached_nodes, cached_edges, cached_hyperedges, uncached_paths = (
+                    _check_semantic_cache(sem_paths_str, root=out_root, mode=sem_cache_mode)
+                )
             sem_cache_hits = len(semantic_files) - len(uncached_paths)
             sem_cache_misses = len(uncached_paths)
             sem_result["nodes"].extend(cached_nodes)
@@ -2570,6 +2614,7 @@ def dispatch_command(cmd: str) -> None:
                         fresh.get("hyperedges", []),
                         root=out_root,
                         allowed_source_files=uncached_paths,
+                        mode=sem_cache_mode,
                     )
                 except Exception as exc:
                     print(f"[graphify extract] warning: could not write semantic cache: {exc}", file=sys.stderr)
@@ -2880,27 +2925,41 @@ def dispatch_command(cmd: str) -> None:
         stages.total()
 
     elif cmd == "cache-check":
-        # graphify cache-check <files_from> [--root <dir>]
+        # graphify cache-check <files_from> [--root <dir>] [--mode <m> | --deep]
         # Reads file paths (one per line) from <files_from>, checks semantic cache.
+        # --mode deep (or --deep) checks the cache/semantic-deep/ namespace
+        # written by `extract --mode deep` instead of cache/semantic/ (#1894).
         # Writes:
         #   graphify-out/.graphify_cached.json   — already-cached nodes/edges/hyperedges
         #   graphify-out/.graphify_uncached.txt  — paths that need extraction
         # Stdout: "Cache: N hit, M miss"
         from graphify.cache import check_semantic_cache
         if len(sys.argv) < 3:
-            print("Usage: graphify cache-check <files_from> [--root <dir>]", file=sys.stderr)
+            print("Usage: graphify cache-check <files_from> [--root <dir>] [--mode <m> | --deep]", file=sys.stderr)
             sys.exit(1)
         files_from = Path(sys.argv[2])
         root = Path(".")
+        cache_mode: str | None = None
         i = 3
         while i < len(sys.argv):
             if sys.argv[i] == "--root" and i + 1 < len(sys.argv):
                 root = Path(sys.argv[i + 1])
                 i += 2
+            elif sys.argv[i] == "--mode" and i + 1 < len(sys.argv):
+                cache_mode = sys.argv[i + 1]
+                i += 2
+            elif sys.argv[i].startswith("--mode="):
+                cache_mode = sys.argv[i].split("=", 1)[1]
+                i += 1
+            elif sys.argv[i] == "--deep":
+                cache_mode = "deep"
+                i += 1
             else:
                 i += 1
         files = [f for f in files_from.read_text(encoding="utf-8").splitlines() if f.strip()]
-        cached_nodes, cached_edges, cached_hyperedges, uncached = check_semantic_cache(files, root)
+        cached_nodes, cached_edges, cached_hyperedges, uncached = check_semantic_cache(
+            files, root, mode=cache_mode
+        )
         out = root / _GRAPHIFY_OUT
         out.mkdir(parents=True, exist_ok=True)
         if cached_nodes or cached_edges or cached_hyperedges:
diff --git a/graphify/llm.py b/graphify/llm.py
index 52e2b48..e3dbf68 100644
--- a/graphify/llm.py
+++ b/graphify/llm.py
@@ -1924,6 +1924,9 @@ def extract_corpus_parallel(
             # chunk leaked the FileSlice object into the allowlist and the write
             # raised TypeError, silently defeating the checkpoint.)
             allowed = [unit_path(item) for item in chunk]
+            # Deep-mode results checkpoint into their own namespace
+            # (cache/semantic-deep/) so a deep run never overwrites standard
+            # entries — and a later standard run never serves deep ones (#1894).
             _scs(
                 result.get("nodes", []),
                 result.get("edges", []),
@@ -1931,6 +1934,7 @@ def extract_corpus_parallel(
                 root=root,
                 merge_existing=True,
                 allowed_source_files=allowed,
+                mode="deep" if deep_mode else None,
             )
         except Exception as _exc:  # noqa: BLE001 — checkpoint is best-effort
             print(f"[graphify] incremental cache checkpoint failed: {_exc}", file=sys.stderr)
diff --git a/tests/test_cache.py b/tests/test_cache.py
index 8588df9..ff89a32 100644
--- a/tests/test_cache.py
+++ b/tests/test_cache.py
@@ -570,6 +570,149 @@ def test_save_semantic_cache_rejects_out_of_scope_source_file(tmp_path):
     assert protected_cache["hyperedges"] == []
 
 
+# --- #1894: mode-namespaced semantic cache -----------------------------------
+# `extract --mode deep` produces richer results than standard extraction, so
+# deep entries live in their own namespace (cache/semantic-deep/). mode=None
+# must stay byte-identical to the historical behavior: older installed skill
+# flows call check/save without the parameter and must be unaffected.
+
+def test_semantic_cache_deep_mode_roundtrip_under_deep_namespace(tmp_path):
+    """mode='deep' saves under cache/semantic-deep/ and reads back from it."""
+    from graphify.cache import check_semantic_cache, save_semantic_cache
+
+    f = tmp_path / "doc.md"
+    f.write_text("# Doc\n\nBody.\n")
+    saved = save_semantic_cache(
+        [{"id": "deep_n", "source_file": "doc.md"}], [], root=tmp_path, mode="deep"
+    )
+    assert saved == 1
+
+    deep_dir = tmp_path / "graphify-out" / "cache" / "semantic-deep"
+    h = file_hash(f, tmp_path)
+    assert (deep_dir / f"{h}.json").exists(), (
+        "deep entry must land under cache/semantic-deep/"
+    )
+    # And NOT in the plain namespace.
+    plain_dir = tmp_path / "graphify-out" / "cache" / "semantic"
+    assert not (plain_dir / f"{h}.json").exists()
+
+    nodes, edges, hyper, uncached = check_semantic_cache(
+        [str(f)], root=tmp_path, mode="deep"
+    )
+    assert [n["id"] for n in nodes] == ["deep_n"]
+    assert uncached == []
+
+
+def test_semantic_cache_deep_invisible_to_plain_reads_and_vice_versa(tmp_path):
+    """Deep entries must not satisfy mode=None reads (and plain entries must
+    not satisfy deep reads) — the namespaces are fully isolated."""
+    from graphify.cache import check_semantic_cache, save_semantic_cache
+
+    deep_doc = tmp_path / "deep.md"
+    deep_doc.write_text("# Deep\n")
+    plain_doc = tmp_path / "plain.md"
+    plain_doc.write_text("# Plain\n")
+
+    save_semantic_cache([{"id": "d", "source_file": "deep.md"}], [],
+                        root=tmp_path, mode="deep")
+    save_semantic_cache([{"id": "p", "source_file": "plain.md"}], [],
+                        root=tmp_path)  # mode omitted: historical call shape
+
+    # Plain read: deep entry is a miss, plain entry is a hit.
+    nodes, _, _, uncached = check_semantic_cache(
+        [str(deep_doc), str(plain_doc)], root=tmp_path
+    )
+    assert [n["id"] for n in nodes] == ["p"]
+    assert uncached == [str(deep_doc)]
+
+    # Deep read: mirror image.
+    nodes, _, _, uncached = check_semantic_cache(
+        [str(deep_doc), str(plain_doc)], root=tmp_path, mode="deep"
+    )
+    assert [n["id"] for n in nodes] == ["d"]
+    assert uncached == [str(plain_doc)]
+
+
+def test_semantic_cache_mode_none_layout_unchanged(tmp_path):
+    """Omitting mode writes exactly the historical cache/semantic/ layout —
+    forward-compat for older installed callers that never pass mode."""
+    from graphify.cache import check_semantic_cache, save_semantic_cache
+
+    f = tmp_path / "doc.md"
+    f.write_text("# Doc\n")
+    save_semantic_cache([{"id": "n", "source_file": "doc.md"}], [], root=tmp_path)
+    h = file_hash(f, tmp_path)
+    assert (tmp_path / "graphify-out" / "cache" / "semantic" / f"{h}.json").exists()
+    assert not (tmp_path / "graphify-out" / "cache" / "semantic-deep").exists(), (
+        "mode=None must never create the deep namespace"
+    )
+    nodes, _, _, uncached = check_semantic_cache([str(f)], root=tmp_path)
+    assert [n["id"] for n in nodes] == ["n"] and uncached == []
+
+
+def test_clear_cache_removes_deep_namespace(tmp_path):
+    """clear_cache sweeps cache/semantic-deep/ alongside semantic/ and ast/."""
+    from graphify.cache import save_semantic_cache
+
+    f = tmp_path / "doc.md"
+    f.write_text("# Doc\n")
+    save_semantic_cache([{"id": "p", "source_file": "doc.md"}], [], root=tmp_path)
+    save_semantic_cache([{"id": "d", "source_file": "doc.md"}], [],
+                        root=tmp_path, mode="deep")
+    base = tmp_path / "graphify-out" / "cache"
+    assert list((base / "semantic").glob("*.json"))
+    assert list((base / "semantic-deep").glob("*.json"))
+
+    clear_cache(tmp_path)
+    assert not list(base.rglob("*.json")), (
+        "clear_cache must remove entries in BOTH semantic namespaces"
+    )
+
+
+def test_cached_files_includes_deep_namespace(tmp_path):
+    """cached_files reports deep-namespace entries too."""
+    from graphify.cache import save_semantic_cache
+
+    f = tmp_path / "doc.md"
+    f.write_text("# Doc\n")
+    save_semantic_cache([{"id": "d", "source_file": "doc.md"}], [],
+                        root=tmp_path, mode="deep")
+    assert file_hash(f, tmp_path) in cached_files(tmp_path)
+
+
+def test_semantic_prune_sweeps_both_namespaces_against_same_live_set(tmp_path):
+    """#1894 follow-up to #1527: prune must sweep cache/semantic/ AND
+    cache/semantic-deep/ against the SAME live-hash set (liveness is
+    content-based, mode-independent). Orphans go in both namespaces; live
+    entries survive in both."""
+    from graphify.cache import prune_semantic_cache, save_semantic_cache
+
+    f = tmp_path / "doc.md"
+    f.write_text("# A\n\nContent A.\n")
+    h_old = file_hash(f, tmp_path)
+    save_semantic_cache([{"id": "pa", "source_file": "doc.md"}], [], root=tmp_path)
+    save_semantic_cache([{"id": "da", "source_file": "doc.md"}], [],
+                        root=tmp_path, mode="deep")
+
+    f.write_text("# B\n\nContent B.\n")
+    h_live = file_hash(f, tmp_path)
+    save_semantic_cache([{"id": "pb", "source_file": "doc.md"}], [], root=tmp_path)
+    save_semantic_cache([{"id": "db", "source_file": "doc.md"}], [],
+                        root=tmp_path, mode="deep")
+
+    plain_dir = tmp_path / "graphify-out" / "cache" / "semantic"
+    deep_dir = tmp_path / "graphify-out" / "cache" / "semantic-deep"
+    for d in (plain_dir, deep_dir):
+        assert (d / f"{h_old}.json").exists()
+        assert (d / f"{h_live}.json").exists()
+
+    pruned = prune_semantic_cache(tmp_path, {h_live})
+    assert pruned == 2, "one orphan in EACH namespace must be pruned"
+    for d in (plain_dir, deep_dir):
+        assert not (d / f"{h_old}.json").exists(), f"orphan survived in {d.name}"
+        assert (d / f"{h_live}.json").exists(), f"live entry pruned from {d.name}"
+
+
 def test_save_semantic_cache_merge_existing_unions(tmp_path):
     """#1715: merge_existing=True unions with the prior entry so a file split
     across chunks (checkpointed per chunk) keeps every slice."""
diff --git a/tests/test_chunking.py b/tests/test_chunking.py
index 546503a..a978a5d 100644
--- a/tests/test_chunking.py
+++ b/tests/test_chunking.py
@@ -326,6 +326,38 @@ def test_checkpoint_scopes_cache_writes_to_chunk_files(tmp_path):
     assert a_cache and any(n["id"] == "a_ok" for n in a_cache["nodes"])
 
 
+def test_checkpoint_writes_deep_namespace_in_deep_mode(tmp_path):
+    """#1894: the per-chunk checkpoint must follow the run's mode — a
+    deep_mode=True run checkpoints into cache/semantic-deep/, leaving the
+    standard cache/semantic/ namespace untouched (and vice versa)."""
+    from graphify.llm import extract_corpus_parallel
+    from graphify.cache import load_cached
+
+    doc = tmp_path / "doc.md"
+    doc.write_text("# Doc\n\nsome content\n")
+
+    def ok(chunk, **kwargs):
+        return {
+            "nodes": [{"id": "d1", "source_file": "doc.md", "file_type": "document"}],
+            "edges": [], "hyperedges": [], "input_tokens": 1, "output_tokens": 1,
+        }
+
+    with patch("graphify.llm.extract_files_direct", side_effect=ok):
+        extract_corpus_parallel(
+            [doc], backend="kimi", root=tmp_path,
+            token_budget=None, chunk_size=1, max_concurrency=1,
+            deep_mode=True,
+        )
+
+    deep = load_cached(doc, tmp_path, kind="semantic-deep")
+    assert deep and [n["id"] for n in deep["nodes"]] == ["d1"], (
+        "deep-mode checkpoint must land in cache/semantic-deep/"
+    )
+    assert load_cached(doc, tmp_path, kind="semantic") is None, (
+        "deep-mode checkpoint must not write the standard semantic namespace"
+    )
+
+
 def test_omitted_documents_are_reconciled_and_warned(tmp_path, capsys):
     """#1890: a chunk can return a clean, non-empty response that omits some of the
     documents it was given. Those docs must not vanish silently — the run reports
diff --git a/tests/test_extract_cli.py b/tests/test_extract_cli.py
index 3442a48..6ef1b2c 100644
--- a/tests/test_extract_cli.py
+++ b/tests/test_extract_cli.py
@@ -222,6 +222,164 @@ def test_stamped_manifest_files_normalizes_both_sides(tmp_path):
     assert out["document"] == [str(fresh_doc), str(cached_doc)]
 
 
+# --- #1894: --force and deep-mode dispatch over a warm cache -----------------
+
+def _recording_extractor(calls):
+    """extract_corpus_parallel stand-in that records each dispatch."""
+    def _extract(paths, **kwargs):
+        calls.append({"paths": [str(p) for p in paths], "kwargs": kwargs})
+        on_chunk = kwargs.get("on_chunk_done")
+        if on_chunk:
+            on_chunk(0, 1, {"nodes": [], "edges": [], "hyperedges": []})
+        return {
+            "nodes": [{"id": "readme", "source_file": "README.md",
+                       "file_type": "document"}],
+            "edges": [],
+            "hyperedges": [],
+            "input_tokens": 10,
+            "output_tokens": 5,
+        }
+    return _extract
+
+
+def _run_extract(monkeypatch, argv):
+    monkeypatch.setattr(mainmod.sys, "argv", argv)
+    try:
+        mainmod.main()
+    except SystemExit as exc:
+        assert exc.code in (None, 0), f"unexpected exit code {exc.code}"
+
+
+def test_extract_mode_deep_dispatches_over_warm_cache(monkeypatch, tmp_path):
+    """#1894 repro: over a warm manifest + warm standard semantic cache,
+    `extract --mode deep` was a silent no-op — the incremental gate dispatched
+    zero files before the cache was ever consulted, and the cache key ignored
+    mode anyway. Deep must re-dispatch on the first deep run (deep namespace
+    cold) and be served from cache/semantic-deep/ on the second."""
+    corpus = _make_corpus(tmp_path)
+    monkeypatch.setenv("ANTHROPIC_API_KEY", "sk-test-fake-key")
+    monkeypatch.delenv("GRAPHIFY_FORCE", raising=False)
+    calls: list[dict] = []
+    monkeypatch.setattr("graphify.llm.extract_corpus_parallel",
+                        _recording_extractor(calls))
+    monkeypatch.setattr(mainmod, "_check_skill_version", lambda _: None)
+
+    # No --out: the default layout (graphify-out/ beside the sources) keeps the
+    # CLI-level cache write's root anchored at the corpus, so the stub's
+    # root-relative source_file resolves (real runs also checkpoint per chunk
+    # inside llm.extract_corpus_parallel, which this stub replaces).
+    base = ["graphify", "extract", str(corpus), "--backend", "claude",
+            "--no-cluster"]
+
+    # Run 1: cold standard extraction — warms manifest + plain semantic cache.
+    _run_extract(monkeypatch, base)
+    assert len(calls) == 1
+
+    # Sanity: a warm standard re-run dispatches nothing (expected behavior).
+    _run_extract(monkeypatch, base)
+    assert len(calls) == 1
+
+    # The repro: warm tree + --mode deep MUST dispatch.
+    _run_extract(monkeypatch, base + ["--mode", "deep"])
+    assert len(calls) == 2, (
+        "--mode deep over a warm cache must re-dispatch (#1894)"
+    )
+    assert calls[1]["paths"] == [str(corpus / "README.md")]
+    assert calls[1]["kwargs"].get("deep_mode") is True
+
+    # Second deep run: served from the (now warm) deep namespace, no dispatch.
+    _run_extract(monkeypatch, base + ["--mode", "deep"])
+    assert len(calls) == 2, (
+        "second deep run must be served from cache/semantic-deep/"
+    )
+    # The deep entry landed in its own namespace, not cache/semantic/.
+    assert any((corpus / "graphify-out" / "cache" / "semantic-deep").glob("*.json"))
+
+
+def test_extract_force_flag_redispatches_and_stamps_manifest(monkeypatch, tmp_path):
+    """extract accepts --force: a warm tree re-dispatches every semantic file
+    (cache read skipped, incremental gate off) and the manifest is still
+    stamped afterward (#1897-compatible full coverage)."""
+    import json
+
+    corpus = _make_corpus(tmp_path)
+    monkeypatch.setenv("ANTHROPIC_API_KEY", "sk-test-fake-key")
+    monkeypatch.delenv("GRAPHIFY_FORCE", raising=False)
+    calls: list[dict] = []
+    monkeypatch.setattr("graphify.llm.extract_corpus_parallel",
+                        _recording_extractor(calls))
+    monkeypatch.setattr(mainmod, "_check_skill_version", lambda _: None)
+
+    base = ["graphify", "extract", str(corpus), "--backend", "claude",
+            "--no-cluster"]
+
+    _run_extract(monkeypatch, base)
+    assert len(calls) == 1
+    _run_extract(monkeypatch, base)  # warm: no dispatch
+    assert len(calls) == 1
+
+    _run_extract(monkeypatch, base + ["--force"])
+    assert len(calls) == 2, (
+        "--force over a warm tree must re-dispatch every semantic file"
+    )
+    assert calls[1]["paths"] == [str(corpus / "README.md")]
+
+    # The forced run still wrote the semantic cache and stamped the manifest.
+    assert any((corpus / "graphify-out" / "cache" / "semantic").glob("*.json"))
+    manifest = json.loads(
+        (corpus / "graphify-out" / "manifest.json").read_text()
+    )
+    assert manifest.get("README.md", {}).get("semantic_hash"), (
+        "forced re-dispatch must still stamp the manifest"
+    )
+    assert manifest.get("main.go", {}).get("semantic_hash")
+
+
+def test_extract_graphify_force_env_redispatches(monkeypatch, tmp_path):
+    """GRAPHIFY_FORCE=1 behaves like --force (env parity with `update`)."""
+    corpus = _make_corpus(tmp_path)
+    monkeypatch.setenv("ANTHROPIC_API_KEY", "sk-test-fake-key")
+    monkeypatch.delenv("GRAPHIFY_FORCE", raising=False)
+    calls: list[dict] = []
+    monkeypatch.setattr("graphify.llm.extract_corpus_parallel",
+                        _recording_extractor(calls))
+    monkeypatch.setattr(mainmod, "_check_skill_version", lambda _: None)
+
+    base = ["graphify", "extract", str(corpus), "--backend", "claude",
+            "--no-cluster"]
+
+    _run_extract(monkeypatch, base)
+    assert len(calls) == 1
+    _run_extract(monkeypatch, base)  # warm: no dispatch
+    assert len(calls) == 1
+
+    monkeypatch.setenv("GRAPHIFY_FORCE", "1")
+    _run_extract(monkeypatch, base)
+    assert len(calls) == 2, "GRAPHIFY_FORCE=1 must force a re-dispatch"
+
+
+def test_cache_check_mode_deep_reads_deep_namespace(monkeypatch, tmp_path, capsys):
+    """cache-check --mode deep consults cache/semantic-deep/; without the flag
+    it keeps reading cache/semantic/ (deep entries are invisible to it)."""
+    from graphify.cache import save_semantic_cache
+
+    doc = tmp_path / "doc.md"
+    doc.write_text("# Doc\n")
+    save_semantic_cache([{"id": "d", "source_file": "doc.md"}], [],
+                        root=tmp_path, mode="deep")
+    files_from = tmp_path / "files.txt"
+    files_from.write_text(str(doc) + "\n")
+    monkeypatch.setattr(mainmod, "_check_skill_version", lambda _: None)
+
+    _run_extract(monkeypatch, ["graphify", "cache-check", str(files_from),
+                               "--root", str(tmp_path)])
+    assert "Cache: 0 hit, 1 miss" in capsys.readouterr().out
+
+    _run_extract(monkeypatch, ["graphify", "cache-check", str(files_from),
+                               "--root", str(tmp_path), "--mode", "deep"])
+    assert "Cache: 1 hit, 0 miss" in capsys.readouterr().out
+
+
 def _code_only_corpus(tmp_path):
     """A corpus with only code — no docs/papers/images."""
     (tmp_path / "auth.py").write_text(