Using Bricklayer decision-matrix.md to steer agents before they modify code

Just enough configuration to tell Your AI agent what to check before it changes the risky parts of Your project.

Every agent file Bricklayer generates (CLAUDE.md, .cursorrules, AGENTS.md…) has a “Before Modifying Magento Code” table near the top. It maps a kind of change to the runtime check and the guidelines the agent should load first. Near the top matters: it is one of the first things the agent reads.

The bundled rows cover generic Magento situations. Your project has its own dangerous places: the ERP sync, the custom checkout step, the price calculation everybody is afraid of. .bricklayer/decision-matrix.md lets You add rows for those.

Format

  • Create the file:

    • .bricklayer/decision-matrix.md

  • Rows only. Every line must be a valid markdown table row; header and separator lines are ignored if You add them. Judging by the wiki example, each row has three cells: the situation, the runtime check, and the guidelines to load:

| Modifying ERP sync logic | `code-runner` to inspect `Vendor\Erp\Model\SyncQueue` | `development-context category=erp-integration` |
| Changing checkout steps | `plugin-list className=Magento\Checkout\Model\Type\Onepage` | `development-context category=checkout` |

Open Your generated agent file once to see the exact headers of the table, and match the cell order.

Writing good rows

  • Situation in the agent’s words - “Changing product prices”, not “PriceEngine refactor ticket #123”. The agent matches the task it got against this column
  • A concrete check - name the tool and the class or topic: check-class className=..., message-queue-inspect topic=..., eav-attributes. “Be careful” is not a check
  • Point to Your skills - the third cell is where local skills pay off: development-context category=erp-integration
  • Only risky places - five good rows beat thirty. If everything is flagged, nothing is

A few more example rows for a typical store:

| Changing product price calculation | `plugin-list className=Magento\Catalog\Model\Product method=getPrice` | `development-context category=pricing-rules` |
| Adding a product attribute | `eav-attributes` for `catalog_product` | `development-context category=eav` |
| Touching stock sync | `message-queue-inspect topic=acme.erp.stock` | `development-context category=erp-integration` |

pricing-rules here is a local skill You would have to write yourself, eav is bundled.

Regenerate

vendor/bin/bricklayer update

Your rows are appended to the bundled ones in every agent file You selected during install. Check the generated file once to make sure the table renders, a missing | breaks the row.

  • Commit .bricklayer/decision-matrix.md with the regenerated agent files
  • Pair it with project-context.md (the map) and local skills (the details). The matrix is the trigger that sends the agent to them

Start coding!

Source: Project-Local Overrides wiki