diff --git a/studio/backend/core/inference/llama_cpp.py b/studio/backend/core/inference/llama_cpp.py
index bf8a3c04df..f58bd7750c 100644
--- a/studio/backend/core/inference/llama_cpp.py
+++ b/studio/backend/core/inference/llama_cpp.py
@@ -487,6 +487,8 @@ def _build_ngram_mod_flags(
     n_match: int = 24,
     n_min: int = 48,
     n_max: int = 64,
+    *,
+    chain_with_mtp: bool = False,
 ) -> list[str]:
     """Emit the right ngram-mod knob flags for the running llama-server.
 
@@ -496,9 +498,19 @@ def _build_ngram_mod_flags(
     ``probe_server_capabilities``; ``ngram_mod_flavor`` tells us which
     set is real (vs a removal-stub entry). Returns ``[]`` when neither
     set is available so the caller can drop ngram-mod entirely.
+
+    ``chain_with_mtp`` is set by the chained MTP+ngram emit path on
+    legacy builds, where ``--draft-max`` is shared between MTP (number
+    of draft tokens per pass; small, e.g. 2) and ngram-mod (max ngram
+    size N; large, e.g. 64). Emitting both produces a duplicate flag
+    and last-wins clobbers the MTP draft-length the user picked. When
+    set, skip the ngram-mod ``--draft-max`` so MTP's emission wins.
     """
     flavor = caps.get("ngram_mod_flavor") if caps else None
     if flavor == "new":
+        # New-flavor knobs are distinct flag names (``--spec-ngram-mod-*``),
+        # so they never collide with MTP's ``--spec-draft-n-max``; emit all
+        # three regardless of chain_with_mtp.
         return [
             "--spec-ngram-mod-n-match",
             str(n_match),
@@ -511,14 +523,18 @@ def _build_ngram_mod_flags(
         # Legacy llama.cpp before the spec arg rename: same knobs lived
         # under --spec-ngram-size-n (lookup length) and the generic
         # --draft-min / --draft-max (ngram size N range).
-        return [
+        out = [
             "--spec-ngram-size-n",
             str(n_match),
             "--draft-min",
             str(n_min),
-            "--draft-max",
-            str(n_max),
         ]
+        if not chain_with_mtp:
+            # Only safe to set --draft-max here when MTP is NOT in the
+            # same emission; otherwise this duplicates MTP's --draft-max
+            # and last-wins clobbers the MTP draft length.
+            out.extend(["--draft-max", str(n_max)])
+        return out
     return []
 
 
@@ -531,6 +547,15 @@ _LEGACY_SPEC_MODE_MAP = {
     "default": "auto",
     "draft-mtp": "mtp",
     "ngram-mod": "ngram",
+    # llama.cpp's own ``--spec-type none`` spelling, plus the common
+    # English ``disable`` / ``disabled`` aliases external API callers
+    # use, all mean "do not engage speculative decoding". Without an
+    # explicit mapping these strings fall through the comma-parser
+    # below to ``auto``, which silently enables MTP -- the opposite of
+    # the user's intent. Map them to canonical ``off``.
+    "none": "off",
+    "disable": "off",
+    "disabled": "off",
 }
 
 
@@ -3504,7 +3529,10 @@ class LlamaCppBackend:
             draft_n_max = _resolved_draft_n_max()
             n_max_flag = caps.get("spec_draft_n_max_flag") or "--spec-draft-n-max"
             if chain_ngram:
-                ngram_knobs = _build_ngram_mod_flags(caps)
+                # chain_with_mtp suppresses ngram-mod's --draft-max on
+                # legacy builds so it does not collide with MTP's draft
+                # length set just above.
+                ngram_knobs = _build_ngram_mod_flags(caps, chain_with_mtp = True)
                 if ngram_knobs:
                     spec_value = f"ngram-mod,{mtp_token}"
                 else:
@@ -3539,9 +3567,27 @@ class LlamaCppBackend:
         def _emit_ngram_mod() -> bool:
             """Append --spec-type ngram-mod + flag-set knobs."""
             ngram_caps = self.probe_server_capabilities(binary)
+            # Skip emission when the binary advertises no ngram-mod
+            # support at all (no knobs probed under either flavor).
+            # llama-server rejects ``--spec-type ngram-mod`` on those
+            # builds, so emitting it would refuse to start the server
+            # instead of silently disabling spec. Mirror the auto-path
+            # fallback at the elif _mtp_too_small branch below: log and
+            # return False, leaving the caller to load without spec.
+            if not (ngram_caps and ngram_caps.get("supports_ngram_mod")):
+                logger.warning(
+                    "Requested ngram-mod speculative decoding but "
+                    "llama-server does not advertise ngram-mod support; "
+                    "run `unsloth studio update`. Loading without "
+                    "speculative decoding."
+                )
+                return False
             ngram_knobs = _build_ngram_mod_flags(ngram_caps)
             flags.extend(["--spec-type", "ngram-mod"])
             if not ngram_knobs:
+                # supports_ngram_mod is True but knobs returned empty
+                # (shouldn't happen given the flavor check, but kept
+                # for defensive logging).
                 logger.warning(
                     "llama-server lacks ngram-mod tuning "
                     "flags; loading without --spec-ngram-mod-* knobs"
@@ -3688,12 +3734,22 @@ class LlamaCppBackend:
         # engaged. Compare on the resolved spec rather than the requested
         # mode so an Auto request that auto-promoted to draft-mtp under
         # the hood still bounces a reload when the user changes n_max.
-        if (
-            self._speculative_type == "draft-mtp"
-            and spec_draft_n_max is not None
-            and int(spec_draft_n_max) != (self._spec_draft_n_max or 0)
-        ):
-            return False
+        #
+        # ``_spec_draft_n_max`` is None when the backend was loaded with
+        # the platform default (no explicit override); ``None`` on either
+        # side means "platform default". Reload when:
+        #   * both sides explicit and differ, OR
+        #   * request is None but backend has an explicit value (user is
+        #     clearing the override back to default), OR
+        #   * request is explicit but backend is on default (user is
+        #     setting a fresh override).
+        if self._speculative_type == "draft-mtp":
+            req_n = spec_draft_n_max
+            backend_n = self._spec_draft_n_max
+            if (req_n is None) != (backend_n is None):
+                return False
+            if req_n is not None and int(req_n) != int(backend_n):
+                return False
 
         if (self._chat_template_override or None) != (chat_template_override or None):
             return False
diff --git a/studio/backend/routes/inference.py b/studio/backend/routes/inference.py
index 02270ab405..1d397cdc94 100644
--- a/studio/backend/routes/inference.py
+++ b/studio/backend/routes/inference.py
@@ -504,10 +504,21 @@ def _request_matches_loaded_settings(
     backend_mode = llama_backend.requested_spec_mode or "auto"
     if req_mode != backend_mode:
         return False
-    # spec_draft_n_max only matters when an MTP variant is engaged; None
-    # means "platform default" and matches whatever the backend chose.
-    if backend_mode in ("mtp", "mtp+ngram") and request.spec_draft_n_max is not None:
-        if int(request.spec_draft_n_max) != (llama_backend.spec_draft_n_max or 0):
+    # spec_draft_n_max only matters when an MTP variant is ACTUALLY
+    # engaged. Mirror the backend-side guard's check against the
+    # RESOLVED spec mode (``llama_backend.speculative_type``) rather
+    # than the requested UI mode -- an Auto request that auto-promoted
+    # to ``draft-mtp`` has ``requested_spec_mode = "auto"`` but still
+    # honours user n_max changes. ``None`` on either side means
+    # "platform default"; reload when the explicit/default state flips
+    # (clear-to-default or set-from-default) or when both explicit
+    # values differ.
+    if llama_backend.speculative_type == "draft-mtp":
+        req_n = request.spec_draft_n_max
+        backend_n = llama_backend.spec_draft_n_max
+        if (req_n is None) != (backend_n is None):
+            return False
+        if req_n is not None and int(req_n) != int(backend_n):
             return False
     if (request.chat_template_override or None) != (
         llama_backend.chat_template_override or None
diff --git a/studio/backend/tests/test_llama_cpp_mtp_detection.py b/studio/backend/tests/test_llama_cpp_mtp_detection.py
index 4a8276adc0..70289c2771 100644
--- a/studio/backend/tests/test_llama_cpp_mtp_detection.py
+++ b/studio/backend/tests/test_llama_cpp_mtp_detection.py
@@ -34,6 +34,9 @@ for _exc in (
     "ReadError",
     "RemoteProtocolError",
     "CloseError",
+    "HTTPError",
+    "HTTPStatusError",
+    "RequestError",
 ):
     setattr(_httpx_stub, _exc, type(_exc, (Exception,), {}))
 _httpx_stub.Timeout = type("T", (), {"__init__": lambda s, *a, **k: None})
@@ -46,6 +49,19 @@ _httpx_stub.Client = type(
         "__exit__": lambda s, *a: None,
     },
 )
+# AsyncClient instantiated at module load time in
+# core/inference/external_provider.py; tests that import routes.inference
+# need this stub. The methods do not have to work -- nothing in the
+# route reload guard exercises them.
+_httpx_stub.AsyncClient = type(
+    "AC",
+    (),
+    {
+        "__init__": lambda s, **kw: None,
+        "__aenter__": lambda s: s,
+        "__aexit__": lambda s, *a: None,
+    },
+)
 sys.modules.setdefault("httpx", _httpx_stub)
 
 import pytest
@@ -1198,3 +1214,305 @@ def test_build_speculative_flags_mtp_token_missing_logs_and_skips(monkeypatch):
     # _requested_spec_mode still reflects the user's choice.
     assert backend.requested_spec_mode == "mtp"
     assert backend.speculative_type is None
+
+
+# ---------------------------------------------------------------------------
+# Followup regression tests for #5582.
+#
+#   Bug A: route guard at routes/inference.py:509 compared `request.spec_draft_
+#          n_max` against the requested UI mode (which is "auto" for an
+#          auto-promoted draft-mtp load), so a slider change while running
+#          under Auto-promoted MTP returned `already_loaded` and kept the
+#          stale value.
+#   Bug B: both reload guards short-circuited the n_max comparison when the
+#          request cleared back to None ("platform default"), so an explicit
+#          override could never be cleared without a model swap.
+#   Bug C: legacy chained MTP+ngram emitted --draft-max twice (MTP's draft
+#          length, then ngram's size-N max); last-wins clobbered the MTP
+#          value.
+#   Bug D: forced ngram standalone emitted --spec-type ngram-mod even on
+#          binaries that did not advertise ngram-mod support, causing
+#          llama-server to refuse to start.
+#   Bug E: speculative_type="none" (the spelling llama.cpp itself uses for
+#          the disable case, as well as "disable" / "disabled" from
+#          external API callers) fell through the canonicaliser to "auto",
+#          silently enabling MTP when the user said disable.
+# ---------------------------------------------------------------------------
+
+
+# ---- Bug E: "none"/"disable" canonicalise to "off" ----
+
+import pytest as _pytest
+
+
+@_pytest.mark.parametrize(
+    "value",
+    ["none", "None", "NONE", "  none  ", "disable", "Disabled", "DISABLED"],
+)
+def test_canonicalize_spec_mode_none_aliases_map_to_off(value):
+    """Without the followup these all fell through to "auto" and silently
+    re-enabled MTP. They must canonicalise to "off"."""
+    assert _canonicalize_spec_mode(value) == "off"
+
+
+# ---- Bug C: legacy chained MTP+ngram does not duplicate --draft-max ----
+
+
+def test_build_ngram_mod_flags_legacy_chained_omits_draft_max():
+    """When chaining ngram-mod alongside MTP on a legacy llama-server,
+    --draft-max collides with MTP's --draft-max (same flag, different
+    semantic in old builds). The chain_with_mtp flag must suppress the
+    ngram-mod --draft-max so MTP's draft length wins."""
+    caps = {"ngram_mod_flavor": "legacy"}
+    chained = _build_ngram_mod_flags(caps, chain_with_mtp = True)
+    assert "--draft-max" not in chained, (
+        f"chain_with_mtp=True must drop --draft-max on legacy; got {chained}"
+    )
+    # The other two knobs must still be present so ngram-mod actually
+    # tunes the chain.
+    assert "--spec-ngram-size-n" in chained
+    assert "--draft-min" in chained
+
+
+def test_build_ngram_mod_flags_legacy_standalone_keeps_draft_max():
+    """When NOT chaining, --draft-max is the ngram-mod size-N max and must
+    still be emitted on legacy."""
+    caps = {"ngram_mod_flavor": "legacy"}
+    standalone = _build_ngram_mod_flags(caps, chain_with_mtp = False)
+    assert "--draft-max" in standalone
+
+
+def test_build_ngram_mod_flags_new_flavor_always_emits_distinct_names():
+    """The post-rename flavor uses --spec-ngram-mod-* names that never
+    collide with MTP's --spec-draft-n-max, so chain_with_mtp does not
+    matter -- the full knob set is always emitted."""
+    caps = {"ngram_mod_flavor": "new"}
+    chained = _build_ngram_mod_flags(caps, chain_with_mtp = True)
+    standalone = _build_ngram_mod_flags(caps, chain_with_mtp = False)
+    assert chained == standalone
+    assert "--spec-ngram-mod-n-max" in chained
+
+
+def test_build_speculative_flags_chained_mtp_ngram_legacy_no_duplicate_draft_max(
+    monkeypatch,
+):
+    """End-to-end: forced mtp+ngram on a legacy llama-server must emit
+    --draft-max exactly once (the MTP draft length), not twice with a
+    last-wins overwrite from ngram-mod."""
+    fake = {
+        "found": True,
+        "mtp_token": "mtp",
+        "supports_mtp": True,
+        "ngram_mod_flavor": "legacy",
+        "supports_ngram_mod": True,
+        "spec_draft_n_max_flag": "--draft-max",  # legacy n_max flag
+    }
+    monkeypatch.setattr(
+        LlamaCppBackend,
+        "probe_server_capabilities",
+        classmethod(lambda cls, binary = None: fake),
+    )
+    backend = LlamaCppBackend()
+    backend._nextn_predict_layers = 1  # is_mtp_model
+    flags = backend._build_speculative_flags(
+        speculative_type = "mtp+ngram",
+        spec_draft_n_max = 2,
+        extra_args = None,
+        model_identifier = _MTP_MODEL,
+        model_path = None,
+        gpus = True,
+        binary = "/fake/llama-server",
+    )
+    occurrences = [i for i, t in enumerate(flags) if t == "--draft-max"]
+    assert len(occurrences) == 1, (
+        f"--draft-max must appear exactly once on legacy chained MTP+ngram; "
+        f"got {len(occurrences)}: {flags}"
+    )
+    # And the value must be MTP's choice (2), not the ngram size-N max (64).
+    idx = occurrences[0]
+    assert flags[idx + 1] == "2", (
+        f"the single --draft-max must carry the MTP draft length, not "
+        f"ngram's size-N max; got {flags[idx + 1]!r} in {flags}"
+    )
+
+
+# ---- Bug D: forced ngram refuses on binaries with no ngram-mod support ----
+
+
+def test_build_speculative_flags_forced_ngram_without_support_skips_spec(monkeypatch):
+    """A forced ``speculative_type="ngram"`` request on a binary that
+    does not advertise ngram-mod support must NOT emit --spec-type
+    ngram-mod (llama-server would refuse to start); load without spec
+    instead, mirroring the auto-path sub-3B fallback."""
+    backend = _resolver_backend(monkeypatch, ngram_supported = False)
+    backend._nextn_predict_layers = None
+    flags = backend._build_speculative_flags(
+        speculative_type = "ngram",
+        spec_draft_n_max = None,
+        extra_args = None,
+        model_identifier = _NON_MTP_MODEL,
+        model_path = None,
+        gpus = True,
+        binary = "/fake/llama-server",
+    )
+    assert "--spec-type" not in flags, (
+        f"forced ngram must not emit --spec-type when binary lacks "
+        f"ngram-mod support; got {flags}"
+    )
+    assert backend.speculative_type is None
+    # User's UI choice is preserved on the requested-mode round-trip.
+    assert backend.requested_spec_mode == "ngram"
+
+
+def test_build_speculative_flags_forced_ngram_with_support_emits_spec(monkeypatch):
+    """Sanity check the positive case: forced ngram on a supporting
+    binary still emits --spec-type ngram-mod plus the knob set."""
+    backend = _resolver_backend(monkeypatch, ngram_supported = True)
+    backend._nextn_predict_layers = None
+    flags = backend._build_speculative_flags(
+        speculative_type = "ngram",
+        spec_draft_n_max = None,
+        extra_args = None,
+        model_identifier = _NON_MTP_MODEL,
+        model_path = None,
+        gpus = True,
+        binary = "/fake/llama-server",
+    )
+    parsed = _flags_dict(flags)
+    assert parsed.get("--spec-type") == "ngram-mod"
+    assert backend.speculative_type == "ngram-mod"
+
+
+# ---- Bug B: clear-to-None forces reload on the backend guard ----
+
+
+def test_already_in_target_state_clear_explicit_n_max_to_none_forces_reload():
+    """Backend loaded with explicit ``spec_draft_n_max=8``; new request
+    clears the value to None (platform default). Without the followup
+    the guard short-circuited on ``spec_draft_n_max is not None`` and
+    returned True, leaving the old 8 in effect. Must now return False."""
+    backend = _mtp_backend(_spec_draft_n_max = 8)
+    assert (
+        backend._already_in_target_state(
+            gguf_path = None,
+            model_identifier = "unsloth/Qwen3.6-27B-MTP-GGUF",
+            hf_variant = "Q4_K_M",
+            n_ctx = 8192,
+            cache_type_kv = None,
+            speculative_type = None,
+            spec_draft_n_max = None,
+            chat_template_override = None,
+            extra_args = None,
+            is_vision = False,
+        )
+        is False
+    )
+
+
+def test_already_in_target_state_set_n_max_from_default_forces_reload():
+    """Mirror: backend loaded on default (None); new request adds an
+    explicit 8. Must reload."""
+    backend = _mtp_backend(_spec_draft_n_max = None)
+    assert (
+        backend._already_in_target_state(
+            gguf_path = None,
+            model_identifier = "unsloth/Qwen3.6-27B-MTP-GGUF",
+            hf_variant = "Q4_K_M",
+            n_ctx = 8192,
+            cache_type_kv = None,
+            speculative_type = None,
+            spec_draft_n_max = 8,
+            chat_template_override = None,
+            extra_args = None,
+            is_vision = False,
+        )
+        is False
+    )
+
+
+# ---- Bug A + Bug B: route-level guard checks resolved mode + handles None ----
+
+
+class _FakeLoadRequest:
+    """Minimal LoadRequest stand-in for the route guard test."""
+    def __init__(self, **kw):
+        self.max_seq_length = kw.get("max_seq_length", 8192)
+        self.cache_type_kv = kw.get("cache_type_kv", None)
+        self.speculative_type = kw.get("speculative_type", "auto")
+        self.spec_draft_n_max = kw.get("spec_draft_n_max", None)
+        self.chat_template_override = kw.get("chat_template_override", None)
+        self.llama_extra_args = kw.get("llama_extra_args", None)
+
+
+def _auto_promoted_mtp_backend(**overrides):
+    """Backend that's running under draft-mtp because Auto auto-promoted
+    it (requested_spec_mode == "auto", speculative_type == "draft-mtp").
+    """
+    backend = _mtp_backend(
+        _requested_spec_mode = "auto",
+        _speculative_type = "draft-mtp",
+        _spec_draft_n_max = 8,
+        **overrides,
+    )
+    backend._extra_args = None
+    return backend
+
+
+def test_route_guard_auto_promoted_mtp_bounces_on_n_max_change():
+    """Without the followup, route guard compared n_max only when
+    ``backend_mode in ("mtp", "mtp+ngram")`` -- but an Auto-promoted
+    backend has ``requested_spec_mode == "auto"``, so a slider change
+    from 8 -> 2 returned ``already_loaded`` and kept the stale value.
+    Now must compare against the RESOLVED speculative_type."""
+    from routes.inference import _request_matches_loaded_settings
+
+    backend = _auto_promoted_mtp_backend()
+    request = _FakeLoadRequest(
+        speculative_type = "auto",
+        spec_draft_n_max = 2,  # was 8
+    )
+    assert _request_matches_loaded_settings(request, backend) is False
+
+
+def test_route_guard_auto_promoted_mtp_matches_when_n_max_unchanged():
+    """Same setup; same n_max value (8) on both sides; must still match."""
+    from routes.inference import _request_matches_loaded_settings
+
+    backend = _auto_promoted_mtp_backend()
+    request = _FakeLoadRequest(
+        speculative_type = "auto",
+        spec_draft_n_max = 8,
+    )
+    assert _request_matches_loaded_settings(request, backend) is True
+
+
+def test_route_guard_clear_explicit_n_max_to_none_forces_reload():
+    """Backend has explicit 8 (auto-promoted to draft-mtp); request
+    clears to None. Route guard must return False so the reload path
+    runs and re-resolves the default value."""
+    from routes.inference import _request_matches_loaded_settings
+
+    backend = _auto_promoted_mtp_backend()
+    request = _FakeLoadRequest(
+        speculative_type = "auto",
+        spec_draft_n_max = None,
+    )
+    assert _request_matches_loaded_settings(request, backend) is False
+
+
+def test_route_guard_ignores_n_max_when_resolved_spec_is_not_mtp():
+    """Backend resolved to ngram-mod (not draft-mtp); n_max is MTP-only
+    and must not force a reload."""
+    from routes.inference import _request_matches_loaded_settings
+
+    backend = _mtp_backend(
+        _requested_spec_mode = "ngram",
+        _speculative_type = "ngram-mod",
+        _spec_draft_n_max = None,
+    )
+    backend._extra_args = None
+    request = _FakeLoadRequest(
+        speculative_type = "ngram",
+        spec_draft_n_max = 8,  # would force reload if we checked, but shouldn't
+    )
+    assert _request_matches_loaded_settings(request, backend) is True