mcencini · Oct 12, 2026 · Oct 12, 2026 · Oct 12, 2026
diff --git a/docs/api/sequence.md b/docs/api/sequence.md
@@ -60,8 +60,6 @@ in-memory sequence, {func}`read_mrd_description` reads those an MRD stream
 carries ahead of its first acquisition, and
 {meth}`~blochsim.model.Simulator.from_description` simulates any of them.
 
-Reading Pulseq needs pypulseq: `pip install blochsim[pulseq]`.
-
 | Object | Description |
 | --- | --- |
 | {obj}`~blochsim.SequenceDescription` | Event stream and RF resources of one repetition of a sequence. |

diff --git a/docs/developer-guide/internals/description.md b/docs/developer-guide/internals/description.md
@@ -48,8 +48,7 @@ gradient per axis and one ADC window. One block becomes one event: a block with
 a pulse is an RF event, one with an ADC and no pulse an ADC event, any other a
 WAIT. Gradients are not events.
 
-The file is parsed and its trajectory computed by pypulseq
-(`pip install blochsim[pulseq]`); a sequence in memory with pypulseq's reading
+The file is parsed and its trajectory computed by pypulseq; a sequence in memory with pypulseq's reading
 interface, pypulseq's or pypulseqpp's, is read the same way. The gradients are
 read for two things only: the k-space trajectory that places each ADC event,
 and the slice-select amplitude under each pulse's isocentre, the magnitude of

diff --git a/docs/user-guide/index.md b/docs/user-guide/index.md
@@ -127,9 +127,8 @@ pip install "blochsim[cu13]"    # plus the GPU kernels, for a CUDA 13 PyTorch
 
 The GPU kernels are compiled ahead of time and need a driver, not the CUDA
 toolkit. Install the extra that matches PyTorch's CUDA major version; BlochSim
-refuses a mismatched one and names the extra to install. Other extras:
-`pulseq` reads `.seq` files, and `examples` brings the packages the gallery
-imports.
+refuses a mismatched one and names the extra to install. The `examples` extra
+brings the packages the gallery imports.
 
 Check the installation by simulating a fast spin echo for three tissues:
 

diff --git a/examples/01-framework/04-description-based-simulation.py b/examples/01-framework/04-description-based-simulation.py
@@ -24,7 +24,7 @@
 # .. colab-link::
 #    :needs_gpu: 0
 #
-#    !pip install "blochsim[pulseq]" matplotlib
+#    !pip install blochsim matplotlib
 #    !wget --quiet --no-clobber https://raw.githubusercontent.com/pulserver/blochsim/main/docs/figure_style.py
 #    !wget --quiet --no-clobber https://raw.githubusercontent.com/pulserver/blochsim/main/examples/01-framework/fse.seq
 
@@ -136,9 +136,8 @@
 # Pulseq file
 # -----------
 #
-# ``from_pulseq`` reads the description from a ``.seq`` file; it requires the
-# ``pulseq`` extra (``pip install "blochsim[pulseq]"``). The file below is a
-# short FSE:
+# ``from_pulseq`` reads the description from a ``.seq`` file, parsed by
+# pypulseq. The file below is a short FSE:
 from_file = FSESimulator.from_pulseq(SEQ_FILE, states=20)
 file_signal = from_file.simulate(T1=1000.0, T2=torch.tensor([80.0, 110.0]))
 

diff --git a/pyproject.toml b/pyproject.toml
@@ -51,6 +51,9 @@ dependencies = [
 # torch.func (jacrev/jacfwd) and torch.linalg are used by the optimization and
 # estimator packages.
 "torch>=2.1",
+# The format's reference implementation parses a Pulseq .seq file and
+# computes its trajectory.
+"pypulseq>=1.4",
 ]
 
 [project.optional-dependencies]
@@ -64,15 +67,8 @@ cu12 = [
 cu13 = [
 "blochsim-cuda13; sys_platform == 'linux' and platform_machine == 'x86_64'",
 ]
-# What it takes to read a Pulseq .seq file. The format's reference
-# implementation parses it and computes its trajectory; nothing else in the
-# package imports it.
-pulseq = [
-"pypulseq>=1.4",
-]
 # What it takes to run the suite. Nothing here is imported by the package.
 test = [
-"blochsim[pulseq]",
 "pytest>=7.0",
 "pytest-cov",
 "pytest-sugar",
@@ -83,9 +79,6 @@ test = [
 # import while they execute -- those are the ``examples`` extra, so a
 # documentation build without the gallery does not drag them in.
 doc = [
-# The explanation figures and Course lesson 4 read the shipped
-# ``.seq`` file, which pypulseq parses.
-"blochsim[pulseq]",
 "sphinx>=7.0",
 "sphinx_book_theme>=1.1",
 "sphinx-design>=0.6",
@@ -102,7 +95,6 @@ doc = [
 # phantoms, the segmentation, the coils, the Fourier encoding and the linear
 # solvers all come from elsewhere, which is the point several examples make.
 examples = [
-"blochsim[pulseq]",
 "brainweb-dl>=0.3",
 "deepinv>=0.2",
 "deepmriprep>=0.3",

diff --git a/src/blochsim/sequence/_description.py b/src/blochsim/sequence/_description.py
@@ -852,8 +852,6 @@ def from_operators(
     def from_pulseq(cls, source: Any, **settings: Any) -> SequenceDescription:
         """Read one repetition of a Pulseq sequence.
 
-        Requires pypulseq (``pip install blochsim[pulseq]``).
-
         Parameters
         ----------
         source : str, Path or sequence
@@ -872,8 +870,6 @@ def from_pulseq(cls, source: Any, **settings: Any) -> SequenceDescription:
 
         Raises
         ------
-        ImportError
-            If pypulseq is not installed.
         ValueError
             If the file declares no ``TRSize``, ``tr_index`` is out of range,
             or the repetitions differ and none was named.

diff --git a/src/blochsim/sequence/_pulseq.py b/src/blochsim/sequence/_pulseq.py
@@ -4,8 +4,6 @@
 reference implementation of the format. What is added here is the reading a
 simulation needs and Pulseq does not write down: which pulse shapes the RF rows
 share, and which ADC sample each readout passes through k = 0 in.
-
-``pypulseq`` is an optional dependency -- ``pip install blochsim[pulseq]``.
 """
 
 from __future__ import annotations
@@ -45,13 +43,8 @@ def _read(source: Any) -> Any:
     """Return ``source`` if it is a sequence already, or the file it names parsed."""
     if hasattr(source, "block_events"):
         return source
-    try:
-        import pypulseq
-    except ImportError as missing:  # pragma: no cover - exercised by the message
-        raise ImportError(
-            "reading a Pulseq file needs pypulseq, which BlochSim does not "
-            "require otherwise: pip install blochsim[pulseq]"
-        ) from missing
+    import pypulseq
+
     sequence = pypulseq.Sequence()
     sequence.read(str(source))
     return sequence
@@ -354,8 +347,6 @@ def read_pulseq_description(
 
     Raises
     ------
-    ImportError
-        If pypulseq is not installed.
     ValueError
         If the file declares no ``TRSize``, if ``tr_index`` is out of range, or
         if the repetitions differ and none was named.

diff --git a/tests/sequence/test_mrd_reader.py b/tests/sequence/test_mrd_reader.py
@@ -16,6 +16,7 @@
 import struct
 
 import numpy as np
+import pypulseq as pp
 import pytest
 import torch
 
@@ -24,8 +25,6 @@
 from blochsim.sequence import EventType, RfUse, read_mrd_description
 from blochsim.simulators import SPGRSimulator
 
-pp = pytest.importorskip("pypulseq", reason="building the sequence needs pypulseq")
-
 FLIP_DEG = 30.0
 TR_S = 20e-3
 SAMPLES, DWELL_S = 64, 10e-6

diff --git a/tests/sequence/test_pulseq_reader.py b/tests/sequence/test_pulseq_reader.py
@@ -11,6 +11,7 @@
 import math
 
 import numpy as np
+import pypulseq as pp
 import pytest
 import torch
 
@@ -19,8 +20,6 @@
 from blochsim.sequence import AdcRole, EventType, RfUse
 from blochsim.simulators import SPGRSimulator
 
-pp = pytest.importorskip("pypulseq", reason="reading a .seq file needs pypulseq")
-
 FLIP_DEG = 30.0
 TR_S = 20e-3
 FOV_M, SAMPLES, DWELL_S = 0.22, 64, 10e-6