protocol-verification

name	protocol-verification
description	Simulate and analyze Opentrons protocols to verify correctness. Use when asked to verify, simulate, analyze, validate, or check a protocol, or when needing to confirm a newly created protocol works.

Protocol Verification — Simulate & Analyze

After creating or modifying a protocol, verify it using the binaries in api/.venv/bin/. All commands run from the monorepo root.

Prerequisites

The api/ venv must exist. If it doesn't (first time, or after teardown):

make -C api setup

This creates api/.venv/ with all entry points installed. You only need to do this once.

Entry Points

Tool	Binary	Notes
Simulate	api/.venv/bin/opentrons_simulate	Registered script entry point
Analyze	api/.venv/bin/python -m opentrons.cli analyze	Module command — no standalone binary

Do not use uv run for one-off simulate/analyze calls. It checks and potentially rebuilds the venv on every invocation, adding significant latency. Call the venv binaries directly.

Working Directories

All local dev artifacts are gitignored and live at the monorepo root:

Directory	Purpose
tmp-protocols/	Protocol .py files
tmp-custom-labware/	Custom labware .json definitions
tmp-csv/	CSV files for RTP inputs

Simulation

Produces a human-readable runlog of every command the robot would execute. Use for quick validation.

⛔ RTP protocols cannot be simulated. opentrons_simulate has no --rtp-values or --rtp-files flag. If the protocol defines add_parameters() (any RTP — including CSV, int, bool, str, or float), you must tell the user this upfront and use opentrons analyze instead. Do not attempt to simulate an RTP protocol and let it fail; explain the limitation first, then switch to analyze automatically.

# Standard
api/.venv/bin/opentrons_simulate tmp-protocols/my_protocol.py

# With custom labware (can be specified multiple times)
api/.venv/bin/opentrons_simulate tmp-protocols/my_protocol.py \
    -L tmp-custom-labware/

The current working directory is always searched for custom labware implicitly.

Simulation Options

Flag	Description
-l, --log-level	debug, info, warning (default), error, none
-L, --custom-labware-path	Directory to search for custom labware (repeatable)
-e, --estimate-duration	Estimate protocol run time (experimental)
-o, --output	runlog (default) or nothing

Interpreting Results

• Success: runlog prints, exit code 0
• Failure: Python traceback with error message, exit code 1

Common errors:

• DeckConflictError — labware placement conflict
• LabwareDefinitionDoesNotExist — invalid labware name
• OutOfTipsError — not enough tips for the protocol
• LiquidHeightUnknownError — .meniscus() called on a well without load_liquid() — see reference-source-map.md
• IncompatibleAddressableAreaError — wrong slot for robot type

Analysis

Produces structured JSON with predicted commands, labware layout, pipettes, modules, and errors. Use for deep inspection or CI validation. Also the only way to verify protocols with CSV RTPs.

# Standard
api/.venv/bin/python -m opentrons.cli analyze tmp-protocols/my_protocol.py \
    --check --human-json-output=-

# With custom labware — pass the JSON file(s) as extra positional arguments
api/.venv/bin/python -m opentrons.cli analyze \
    tmp-protocols/my_protocol.py \
    tmp-custom-labware/my_custom_plate.json \
    --check --json-output=-

# With primitive RTP values (int, float, bool, str)
api/.venv/bin/python -m opentrons.cli analyze tmp-protocols/my_protocol.py \
    --check --json-output=- \
    --rtp-values='{"sample_count": 8, "dry_run": false}'

# With CSV RTP file
api/.venv/bin/python -m opentrons.cli analyze tmp-protocols/my_protocol.py \
    --check --json-output=- \
    --rtp-files='{"transfer_map": "tmp-csv/transfer_map.csv"}'

# Combined: custom labware + CSV RTP
api/.venv/bin/python -m opentrons.cli analyze \
    tmp-protocols/my_protocol.py \
    tmp-custom-labware/my_custom_plate.json \
    --check --json-output=- \
    --rtp-files='{"transfer_map": "tmp-csv/transfer_map.csv"}'

Analysis Options

Flag	Description
--json-output=FILE	Machine-readable JSON (- for stdout)
--human-json-output=FILE	Pretty-printed JSON (- for stdout)
--check	Exit non-zero if protocol has errors
--rtp-values=JSON	Primitive RTP values as JSON string (int, float, bool, str)
--rtp-files=JSON	CSV RTP file paths as JSON string — keys are variable_names
--log-output=PATH	Log destination (- stdout, stderr default, or file path)
--log-level	DEBUG, INFO, WARNING (default), ERROR

Custom labware in analyze: there is no -L flag. Pass each labware JSON as an extra positional file argument. The analyze command recognizes them by their JSON schema and registers them before running.

JSON Output Structure

{
  "createdAt": "...",
  "result": "ok",
  "robotType": "OT-3",
  "config": {"protocolType": "python", "apiVersion": [2, 28]},
  "metadata": {"protocolName": "..."},
  "commands": [...],
  "labware": [...],
  "pipettes": [...],
  "modules": [...],
  "liquids": [...],
  "errors": [],
  "runTimeParameters": [...]
}

Key fields: result ("ok" / "not-ok" / "parameter-value-required"), errors (empty = valid), commands (full ordered command list).

With Runtime Parameters

api/.venv/bin/python -m opentrons.cli analyze protocol.py \
    --check --json-output=output.json \
    --rtp-values='{"sample_count": 48, "dry_run": false}'

# CSV parameter files
api/.venv/bin/python -m opentrons.cli analyze protocol.py \
    --check --json-output=output.json \
    --rtp-files='{"plate_map": "/path/to/map.csv"}'

Standard Verification Workflow

Before running anything, check whether the protocol defines add_parameters(). If it does, skip simulate entirely and go straight to analyze — then tell the user why.

# 1. Quick check — simulate (only if protocol has NO add_parameters())
api/.venv/bin/opentrons_simulate tmp-protocols/my_protocol.py

# 1b. Quick check — simulate with custom labware (still no RTPs)
api/.venv/bin/opentrons_simulate tmp-protocols/my_protocol.py \
    -L tmp-custom-labware/

# 2. Deep check — analyze (required for any protocol with add_parameters())
api/.venv/bin/python -m opentrons.cli analyze \
    tmp-protocols/my_protocol.py \
    [tmp-custom-labware/my_plate.json] \
    --check --human-json-output=- \
    [--rtp-values='{"key": value}'] \
    [--rtp-files='{"csv_param": "tmp-csv/file.csv"}']

Decision guide:

Scenario	Use	Agent behavior
No RTPs, no custom labware	simulate	Run simulate directly
Custom labware only	simulate with -L	Run simulate directly
Any RTP (add_parameters() present)	analyze only	Tell the user: "opentrons_simulate cannot run RTP protocols — switching to opentrons analyze", then run analyze
Custom labware + any RTP	analyze with extra JSON args	Same — explain, then analyze

Snapshot Testing Integration

For protocols to be tracked for regression, use analyses-snapshot-testing/:

cd analyses-snapshot-testing/

# Naming: {Robot}_{Status}_{Version}_{Pipettes}_{Modules}_{Description}.py
# Example: Flex_S_v2_28_P1000_GRIP_SerialDilution.py

make prep
make snapshot-test-update PROTOCOL_NAMES=Flex_S_v2_28_P1000_GRIP_SerialDilution OVERRIDE_PROTOCOL_NAMES=none

See the analyses-snapshot-testing skill for full details.

Keeping This Skill Current

When simulate or analyze surfaces a new error pattern, constraint, or CLI behavior that isn't already documented here, add it to the Troubleshooting section or update the relevant command example. The next person hitting the same issue will thank you.

Troubleshooting

api/.venv/ doesn't exist

make -C api setup

Simulation succeeds but analysis shows errors

Analysis is stricter. Check the errors array in JSON output for details.

Protocol works in simulation but fails on robot

Simulation doesn't verify physical constraints: actual tip presence, liquid volumes, module calibration, or physical deck geometry.

Slow runs

If you accidentally used uv run instead of the venv binaries, it checks/rebuilds the venv each time. Switch to api/.venv/bin/... for instant invocations.