External model catalog

Local external-model workflows require Kessetsu 1.2.0; typed instance parameters require Kessetsu 1.3.0. This is a small characterized catalog, not a universal model marketplace. Model identity, simulation evidence and physical-device accuracy are distinct.

Supported interfaces

The family describes the electrical interface, not a package, footprint or device rating. Only these catalog-backed interfaces are supported. Arbitrary pin/geometry descriptors are not implemented. A declaration may expose up to 32 existing .SUBCKT header parameters through a unit-typed allowlist; all other coefficients remain fixed by the exact file/version/hash.

Local-file workflow

Start with external_comparator.kess or external_memristor.kess.

The memristor example exposes only Rinit, Vt and stime from its exact library header. Its instance binds the first two through ordinary root parameters, so --param, parameter studies and finite calibration workflows all use the same typed input path. This changes an instance value, not the hash-bound model file.

On the CLI, keep the models/ directory beside the source:

kess test examples/external_comparator.kess
kess test examples/external_memristor.kess
kess export examples/external_memristor.kess --target ltspice --output examples/memristor.asc

On Web, open File → Examples → Local model files, then View → Circuit details. Download the example's model file and select it for its declared resource. No account or upload is involved. Compilation checks its exact hash, entry and positional terminal count; simulation checks the browser profile before loading Ngspice. A selected file's original filename need not match the reference: the selection explicitly binds it to that reference.

Files remain in memory only. Editing source retains bindings but revalidates its metadata; opening a different circuit/new/example clears them. Reloading, browser draft recovery and shared-source links require selecting them again. Changing/clearing a binding discards prior simulation and drawing/export state. Renaming a circuit does not alter model identity.

Native files must be source-relative and contained under the source directory; traversal, absolute paths and unsafe references are rejected. Web bindings use the same references without reading the filesystem implicitly. Limits: 16 MiB per UTF-8 file, 64 bound browser resources, 32 MiB combined browser bytes, 32 KiB per logical library statement and bounded statement/nesting counts. These are resource ceilings, not a hard aggregate memory guarantee.

Characterized models

Kessetsu generic comparator v1

• File: comparator.lib, AGPL-3.0-only.
• Entry: KESSETSU_COMPARATOR_V1, five terminals.
• SHA-256: 00198a3b00ef90c78b93beb6c7e7ed61c9f0220dc597a6c71cd0661343246c34.
• Model: smooth 1 mV input transition, 0.1 V output rail headroom, 50 Ω output resistance.
• Covered setup: 5 V single supply, 100 mV-peak / 1 kHz input around a grounded reference, 10 kΩ load, transient at 1 µs output step for 2 ms. Both polarities of the input and loaded output high/low are checked against fixed independent limits.
• Intended for circuit/workflow verification, not a named manufacturer's comparator. No delay, hysteresis, offset, noise, input-current, common-mode/rating or thermal fidelity is claimed. AC around the transition is not an endorsement of a real comparator's response.
• Native Ngspice and the browser portable profile; expected output low approximately 99.5 mV and high approximately 4.876 V for this load.

Published threshold memristor demonstration

• File: memristor.lib, BSD-3-Clause; retain attribution, license and extraction details.
• Entry: memristor, two terminals. Adapted from the Ngspice example based on Pershin and Di Ventra's threshold model.
• SHA-256: cd4bac38581fb00c1b5667e9d5ec440cf954efb5e26105ae2775853cc90301f6.
• Covered setup: zero-offset 3 V-peak / 100 MHz sine, 100 ps output step for 10 ns, uic, original demonstration defaults: 1 kΩ/10 kΩ bounds, 7 kΩ initial state, 1.6 V threshold, alpha=0, beta=20e3/stime, stime=10n.
• The initial-state and waveform histories matter. Use simulate tran 100ps 10ns uic: this skips the DC operating point and applies capacitor initial conditions. Do not add uic to ordinary circuits by habit. OP/AC and arbitrary pulse/frequency/default combinations are not characterized here. Direct reference comparison uses the same exact library/defaults and initial-condition policy.
• These coefficients are artificial demonstrations, not calibration to a fabricated device. A hysteresis-shaped plot is not proof of physical fidelity or a research pilot.
• The reproducible pulse protocol covers a 24-case amplitude/duration/starting-state matrix, 25 ps versus 12.5 ps timestep refinement and one separately reported held-out stimulus. It characterizes this exact synthetic model; it does not validate a fabricated device.
• Measure terminal current with the explicit series zero-volt VSENSE source; arbitrary subcircuit current/power is not guessed from an internal branch or a resistance value.

Texas Instruments OPA197 / OPAx197 model

• Existing native workflow, official manufacturer download, model Final 1.3, 2022-06-23, OPAx197 PSpice Rev. D. File OPAx197.LIB, entry OPAx197.
• SHA-256: fc5b020e63346e511bd808bf41c856b0150b000bcf8a41fe00eeececb1f422a5.
• Interface: opamp (in_p,in_n,vcc,vee,out) maps exact positional header IN+ IN- VCC VEE OUT. Declare simulator=ngspice_ps redistribution=prohibited.
• User-acquired local evaluation under TI terms; Kessetsu does not redistribute, rewrite, bundle into downloads or silently substitute this manufacturer's file.
• Characterized native OP/AC/transient non-inverting amplifier under the independent manufacturer-model evaluator. This evidence does not validate all data-sheet behavior.
• Native-only: the browser profile does not enable PSpice compatibility or its compiled/code-model dependencies. Selecting it can resolve compilation/geometry; browser simulation explicitly refuses the compatibility mode before execution.

Capability and interchange boundaries

Browser libraries are self-contained Ngspice analog text: .subckt/.ends, header defaults, local .param/.func, and local D/BJT/MOS/switch .model types; analog R/C/L/V/I/D/B, E/G/F/H/Q/M/S and X cards. Subcircuit calls must resolve in the selected library and instance-level SPICE parameter overrides are not in this initial profile. Conservatively rejected tokens/directives may require the CLI even if another simulator accepts them. Controls, includes, .lib, file-loading expressions, top-level devices, analysis/output/options, digital/compiled/plugin cards and unsupported model kinds do not execute on Web. Accepted syntax can still fail solver convergence; such failures are not rewritten to PASS.

All external libraries, including native ones, reject control/include/library/plugin-loading directives and require complete, bounded subcircuit headers/closures. Native Ngspice/PSpice compatibility is broader than the browser profile, not a portability guarantee. OSDI or user-compiled plugin loading needs a separately designed opt-in workflow.

Schematics, manifests, locks and ordinary exports carry dependency identity, never external model bodies. Only the ephemeral browser simulation deck receives validated local text. SPICE/LTspice exports need matching files beside the export at the declared relative paths. KiCad preserves symbols, pins and model metadata, but is not a complete simulator project. Two-terminal LTspice instances use the native rectangular outline with explicit Prefix X; they are subcircuits, not resistor primitives. Ngspice model compatibility is not proof of LTspice simulation compatibility. Read export warnings/losses and keep the original .kess.

See external model declarations, exports and simulation/assertion contracts.