diff --git a/scripts/ci/sync_bundle_lfx_pin.py b/scripts/ci/sync_bundle_lfx_pin.py
index 061a0902a4..f79d2a1790 100644
--- a/scripts/ci/sync_bundle_lfx_pin.py
+++ b/scripts/ci/sync_bundle_lfx_pin.py
@@ -8,11 +8,18 @@ guaranteed to resolve an lfx new enough to carry it.  Before the LFX 0.5.x ->
 no upper bound, which silently permitted resolving against the now-dead 0.5.x
 line -- and neither pip nor uv flags the cross-line jump.
 
-Pin form: ``lfx>=X.Y.0,<(X+1).0.0`` -- floored at the current minor line,
-capped below the next lfx major.  The cap is a coarse install-time guard
-against an untested lfx major; fine-grained BUNDLE_API compatibility is still
-enforced at load time by each ``extension.json``'s ``lfx.compat`` list against
-the running lfx's ``BUNDLE_API_VERSION`` (see
+Pin form: ``lfx>=X.Y.0.dev0,<(X+1).0.0`` -- floored at the very first
+pre-release of the current minor line, capped below the next lfx major.  The
+``.dev0`` floor (not ``X.Y.0``) is load-bearing: nightlies off a release
+branch are canonical ``X.Y.0.devN`` pre-releases, and PEP 440 sorts those
+BELOW ``X.Y.0`` -- a plain ``>=X.Y.0`` floor makes the branch's own nightly
+``lfx`` unresolvable against its own bundles (langflow-base pins
+``lfx==X.Y.0.devN`` exactly, so the resolver cannot back off).  ``X.Y.0.dev0``
+is the lowest version PEP 440 admits in the line, so every devN / rcN / final
+satisfies it while older minor lines stay excluded.  The cap is a coarse
+install-time guard against an untested lfx major; fine-grained BUNDLE_API
+compatibility is still enforced at load time by each ``extension.json``'s
+``lfx.compat`` list against the running lfx's ``BUNDLE_API_VERSION`` (see
 ``src/lfx/src/lfx/extension/manifest.py``).
 
 Idempotent: re-running with the same version is a no-op (so it is safe to call
@@ -53,8 +60,10 @@ _VERSION_RE = re.compile(r"^(\d+)\.(\d+)\.\d+")
 def lfx_floor_spec(version: str) -> str:
     """Return the bundle ``lfx`` dependency spec for a Langflow/LFX version.
 
-    ``"1.10.0"`` -> ``"lfx>=1.10.0,<2.0.0"`` (floor at the minor line start,
-    cap below the next lfx major). A leading ``v`` is tolerated.
+    ``"1.11.0"`` -> ``"lfx>=1.11.0.dev0,<2.0.0"`` (floor at the minor line's
+    first pre-release so the branch's own ``X.Y.0.devN`` nightlies resolve --
+    see the module docstring; cap below the next lfx major). A leading ``v``
+    is tolerated.
 
     NOTE: this floor format is duplicated in ``scripts/migrate/port_bundle.py``
     (``_current_lfx_floor``) so each script stays standalone; keep them in step.
@@ -64,7 +73,7 @@ def lfx_floor_spec(version: str) -> str:
         msg = f"Unparseable version {version!r}; expected X.Y.Z"
         raise ValueError(msg)
     major, minor = int(match.group(1)), int(match.group(2))
-    return f"lfx>={major}.{minor}.0,<{major + 1}.0.0"
+    return f"lfx>={major}.{minor}.0.dev0,<{major + 1}.0.0"
 
 
 def rewrite_lfx_dep(content: str, floor_spec: str) -> str:
diff --git a/scripts/migrate/port_bundle.py b/scripts/migrate/port_bundle.py
index c164024dae..86f6c37f01 100755
--- a/scripts/migrate/port_bundle.py
+++ b/scripts/migrate/port_bundle.py
@@ -69,11 +69,13 @@ def _current_lfx_floor() -> str:
     """Return the ``lfx`` dependency floor for a freshly-ported bundle.
 
     Reads the workspace lfx version from ``src/lfx/pyproject.toml`` and pins
-    ``lfx>=X.Y.0,<(X+1).0.0`` -- floored at the current major.minor line,
-    capped below the next lfx major.  Mirrors ``lfx_floor_spec`` in
-    ``scripts/ci/sync_bundle_lfx_pin.py`` (each script is kept standalone, so
-    keep the two in step); that script re-syncs every existing bundle on
-    ``make patch``.
+    ``lfx>=X.Y.0.dev0,<(X+1).0.0`` -- floored at the current major.minor
+    line's first pre-release (the branch's own canonical ``X.Y.0.devN``
+    nightlies sort below a plain ``X.Y.0`` under PEP 440, so they must be
+    admitted by the floor), capped below the next lfx major.  Mirrors
+    ``lfx_floor_spec`` in ``scripts/ci/sync_bundle_lfx_pin.py`` (each script
+    is kept standalone, so keep the two in step); that script re-syncs every
+    existing bundle on ``make patch``.
     """
     lfx_pyproject = (REPO_ROOT / "src" / "lfx" / "pyproject.toml").read_text(encoding="utf-8")
     match = re.search(r'^version = "(\d+)\.(\d+)\.\d+', lfx_pyproject, re.MULTILINE)
@@ -81,7 +83,7 @@ def _current_lfx_floor() -> str:
         msg = "Could not read lfx version from src/lfx/pyproject.toml"
         raise ValueError(msg)
     major, minor = int(match.group(1)), int(match.group(2))
-    return f"lfx>={major}.{minor}.0,<{major + 1}.0.0"
+    return f"lfx>={major}.{minor}.0.dev0,<{major + 1}.0.0"
 
 
 # ---------------------------------------------------------------------------
diff --git a/src/backend/tests/unit/test_bundle_lfx_pin.py b/src/backend/tests/unit/test_bundle_lfx_pin.py
index 7225bf1cae..4d9988a250 100644
--- a/src/backend/tests/unit/test_bundle_lfx_pin.py
+++ b/src/backend/tests/unit/test_bundle_lfx_pin.py
@@ -36,15 +36,18 @@ mod = _load_module()
 
 
 class TestLfxFloorSpec:
+    # The .dev0 floor is load-bearing: nightlies are canonical X.Y.0.devN
+    # pre-releases, which PEP 440 sorts BELOW X.Y.0, so a plain >=X.Y.0
+    # floor makes the branch's own nightly lfx unresolvable.
     @pytest.mark.parametrize(
         ("version", "expected"),
         [
-            ("1.10.0", "lfx>=1.10.0,<2.0.0"),
-            ("1.10.3", "lfx>=1.10.0,<2.0.0"),  # patch within a minor -> same floor
-            ("1.11.0", "lfx>=1.11.0,<2.0.0"),
-            ("2.0.0", "lfx>=2.0.0,<3.0.0"),
-            ("v1.10.0", "lfx>=1.10.0,<2.0.0"),  # leading v tolerated
-            ("10.4.2", "lfx>=10.4.0,<11.0.0"),  # multi-digit major
+            ("1.10.0", "lfx>=1.10.0.dev0,<2.0.0"),
+            ("1.10.3", "lfx>=1.10.0.dev0,<2.0.0"),  # patch within a minor -> same floor
+            ("1.11.0", "lfx>=1.11.0.dev0,<2.0.0"),
+            ("2.0.0", "lfx>=2.0.0.dev0,<3.0.0"),
+            ("v1.10.0", "lfx>=1.10.0.dev0,<2.0.0"),  # leading v tolerated
+            ("10.4.2", "lfx>=10.4.0.dev0,<11.0.0"),  # multi-digit major
         ],
     )
     def test_floor(self, version, expected):
@@ -62,7 +65,7 @@ class TestLfxFloorSpec:
 
 
 class TestRewriteLfxDep:
-    FLOOR = "lfx>=1.10.0,<2.0.0"
+    FLOOR = "lfx>=1.10.0.dev0,<2.0.0"
 
     def test_rewrites_bare_floor(self):
         assert mod.rewrite_lfx_dep('    "lfx>=0.5.0",', self.FLOOR) == f'    "{self.FLOOR}",'
@@ -121,11 +124,11 @@ class TestSyncBundles:
     def test_sync_updates_and_reports(self, tmp_path):
         bundles = tmp_path / "bundles"
         self._make_bundle(bundles, "arxiv", "lfx>=0.5.0")
-        self._make_bundle(bundles, "ibm", "lfx>=1.10.0,<2.0.0")  # already correct
+        self._make_bundle(bundles, "ibm", "lfx>=1.10.0.dev0,<2.0.0")  # already correct
 
         results = dict(mod.sync_bundles("1.10.0", bundles))
         assert results == {"arxiv": True, "ibm": False}  # arxiv changed, ibm no-op
-        assert '"lfx>=1.10.0,<2.0.0"' in (bundles / "arxiv" / "pyproject.toml").read_text()
+        assert '"lfx>=1.10.0.dev0,<2.0.0"' in (bundles / "arxiv" / "pyproject.toml").read_text()
 
     def test_sync_idempotent(self, tmp_path):
         bundles = tmp_path / "bundles"
diff --git a/src/bundles/NIGHTLY.md b/src/bundles/NIGHTLY.md
index 4344c3852a..75ba6c6b9f 100644
--- a/src/bundles/NIGHTLY.md
+++ b/src/bundles/NIGHTLY.md
@@ -81,6 +81,16 @@ Why (2) is not optional: a bundle pins `lfx>=1.10.0,<2.0.0`, and PEP 440 sorts `
 daily from **main's** workflow definition, so merging this before the gate would break the live
 nightly on the next run.
 
+> **Post-activation fix (2026-06):** condition (2) as stated was still fragile — the `release-1.11.0`
+> fork's `make patch v=1.11.0` re-synced every bundle floor to `lfx>=1.11.0`
+> (`scripts/ci/sync_bundle_lfx_pin.py`), which sorts **above** that same branch's `1.11.0.devN`
+> nightlies and reintroduced exactly this conflict on the very first `1.11.0.dev0` nightly (the
+> workspace-built bundle's metadata shadows the satisfiable PyPI `0.1.1` in the
+> `uv pip install dist/*.whl` test step). The synced floor format is now
+> `lfx>=X.Y.0.dev0,<(X+1).0.0` — `X.Y.0.dev0` is the lowest version PEP 440 admits in the minor
+> line, so every `devN` / `rcN` / final satisfies it while older lines stay excluded, and the gate
+> can no longer regress on future minor forks.
+
 ## A1 vs A2 + remaining follow-ups (decide before activating)
 
 This PR implements the **A1** publish behavior: the separate `langflow-nightly` / `langflow-base-nightly`
diff --git a/src/bundles/arxiv/pyproject.toml b/src/bundles/arxiv/pyproject.toml
index d2c4c29c38..31ce00fa13 100644
--- a/src/bundles/arxiv/pyproject.toml
+++ b/src/bundles/arxiv/pyproject.toml
@@ -15,7 +15,7 @@ keywords = ["langflow", "lfx", "extension", "bundle", "arxiv", "search"]
 # but we list it here as a direct runtime dep so the bundle keeps building
 # even if lfx drops it later.
 dependencies = [
-    "lfx>=1.11.0,<2.0.0",
+    "lfx>=1.11.0.dev0,<2.0.0",
     "defusedxml>=0.7.1,<1.0.0",
 ]
 
diff --git a/src/bundles/docling/pyproject.toml b/src/bundles/docling/pyproject.toml
index 39a646d3a2..7ab16a0d9c 100644
--- a/src/bundles/docling/pyproject.toml
+++ b/src/bundles/docling/pyproject.toml
@@ -14,7 +14,7 @@ keywords = ["langflow", "lfx", "extension", "bundle", "docling", "documents"]
 # base dependency because the bundle exchanges DoclingDocument objects even when
 # conversion happens remotely.
 dependencies = [
-    "lfx>=1.11.0,<2.0.0",
+    "lfx>=1.11.0.dev0,<2.0.0",
     "httpx>=0.28.1,<1.0.0",
     "docling-core>=2.36.1,<3.0.0",
 ]
diff --git a/src/bundles/duckduckgo/pyproject.toml b/src/bundles/duckduckgo/pyproject.toml
index fca53a83eb..65e37f2699 100644
--- a/src/bundles/duckduckgo/pyproject.toml
+++ b/src/bundles/duckduckgo/pyproject.toml
@@ -18,7 +18,7 @@ keywords = ["langflow", "lfx", "extension", "bundle", "duckduckgo", "search"]
 # "lfx": {"compat": [...]} contract.  langchain-community uses the same
 # range the lfx tree does to keep co-installation lockstep.
 dependencies = [
-    "lfx>=1.11.0,<2.0.0",
+    "lfx>=1.11.0.dev0,<2.0.0",
     "langchain-community>=0.4.1,<1.0.0",
     "ddgs>=9.0.0",
 ]
diff --git a/src/bundles/ibm/pyproject.toml b/src/bundles/ibm/pyproject.toml
index cf87ba328f..80edf857a1 100644
--- a/src/bundles/ibm/pyproject.toml
+++ b/src/bundles/ibm/pyproject.toml
@@ -26,7 +26,7 @@ keywords = ["langflow", "lfx", "extension", "bundle", "ibm", "db2", "watsonx", "
 #   3.10-compatible build elsewhere.  Kept in lockstep with langflow-base.
 # * ``langchain-community`` provides the helpers DB2VS leans on.
 dependencies = [
-    "lfx>=1.11.0,<2.0.0",
+    "lfx>=1.11.0.dev0,<2.0.0",
     "langchain-community>=0.4.1,<1.0.0",
     "ibm-db>=3.2.9,<4.0.0; sys_platform != 'linux' or platform_machine != 'aarch64'",
     "ibm-watsonx-ai>=1.3.1,<2.0.0",