configuring-block-policy

Configuring Block Policy

Create or update .satk/block-policy.json — the file that controls which blocks (library or built-in) the agent can use, which are excluded, and which block parameters the agent should not modify.

When to Use

• User asks to set up, create, or configure block policy
• User asks to restrict or exclude blocks
• User wants to prevent the agent from modifying certain block parameters
• building-simulink-models routes here via the policy gate

When NOT to Use

• Actively building a model → building-simulink-models
• Improving block descriptions or categories → simulink-curating-library-kg
• Declaring which libraries exist → Library Setup gate in building-simulink-models

Prerequisites

• .satk/reuse-libraries.json must exist.

Workflow

1. Check state — Does .satk/block-policy.json exist? If yes, load and summarize. If no, start fresh.
2. Policy mode — (skip if no libraries specified) Ask: prefer libraries with built-in fallback, or custom libraries blocks only (no fallback)?
3. Excluded blocks (optional) — Are there any blocks (library or built-in) that should never be placed in your models? Collect referenceBlock + reason.
4. Off-limits parameters (optional) — Are there any block parameters you don't want the agent to modify? Collect referenceBlock + protectedParams[].
5. Save — Validate and write with library.BlockPolicy.save().

API

policyData = struct();
policyData.policyMode = 'approved_blocks_only';
policyData.fallbackToBuiltins = false;
% Excluded — agent will never place these blocks
policyData.blockedBlocks = struct('referenceBlock', 'LegacyLib/OldCtrl', 'reason', 'Superseded');
% Protected params — agent won't modify these values
policyData.blockRules = struct('referenceBlock', 'Lib/SpeedCtrl', ...
    'protectedParams', {{'Kp', 'Ki', 'Kd'}});

library.BlockPolicy.save(projectRoot, policyData);

For defaults (no restrictions):

policyData = library.BlockPolicy.defaults();
library.BlockPolicy.save(projectRoot, policyData);

Schema

{
  "schemaVersion": 1,
  "policyMode": "approved_blocks_only | prefer_customer_libraries",
  "fallbackToBuiltins": false,
  "blockedBlocks": [
    { "referenceBlock": "LegacyLib/OldController", "reason": "Superseded" }
  ],
  "blockRules": [
    { "referenceBlock": "Lib/SpeedController", "protectedParams": ["Kp", "Ki", "Kd", "SampleTime"] }
  ]
}

Validation Rules

• policyMode: must be prefer_customer_libraries or approved_blocks_only
• approved_blocks_only + fallbackToBuiltins: true → rejected (contradictory)
• protectedParams must be a non-empty array of strings
• Malformed policy → error (never silently ignored)

Updating an Existing Policy

When .satk/block-policy.json already exists:

1. Load with library.BlockPolicy.loadRaw(projectRoot, libConfig)
2. Summarize current state — do NOT re-run the full wizard
3. Ask what to change, apply to existing struct, save

Common updates: exclude a block, mark params as off-limits, change mode, remove an entry.

Guardrails

• Never write block-policy.json without user confirmation
• Always validate before saving (library.BlockPolicy.validate(policyData))
• If user provides a block name without the full library path, look it up in the KG to resolve the referenceBlock

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Copyright 2026 The MathWorks, Inc.

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