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createRuleFactory object defaults must reach runtime input

docs/solutions/logic-errors/2026-04-17-create-rule-factory-object-defaults-must-reach-runtime-input.md

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Original Source

createRuleFactory object defaults must reach runtime input

Problem

createRuleFactory accepted object-config defaults like marker: '>', but it did not pass those defaults into the runtime input used by match, enabled, and other factory-resolved values.

That broke real editor flows using object-config factories, even when the rule looked correct in code.

Symptoms

  • In /blocks/basic-blocks-demo, creating a fresh paragraph and typing > could leave a plain paragraph with literal > text.
  • A direct inspection of the shipped blockquote rule showed:
    • enabled === true
    • getBlockStartText() === '>'
    • resolve() === undefined
  • The failure was easiest to see in realistic sequences like:
    • existing demo content
    • insertBreak()
    • insertText('>')
    • insertText(' ')

What Didn't Work

  • Trusting the tiny package unit seam alone.
  • Assuming the default object config was automatically part of the runtime input.
  • Looking only at browser typing before checking the generated rule itself.

Solution

Merge object-config defaults into the runtime factory input before resolving factory values.

The buggy shape only merged options and context:

ts
getMergedInput(context, options)

That dropped defaults defined on the factory config object itself.

The fix introduces factoryOptions and feeds that merged object into runtime resolution:

ts
const factoryOptions =
  typeof configOrBuilder === 'function'
    ? options
    : { ...(configOrBuilder as Record<string, unknown>), ...options };

const getFactoryInput = <TContext extends object>(context: TContext) =>
  getMergedInput(context, factoryOptions);

Then use getFactoryInput(...) everywhere factory values are resolved.

Why This Works

Object-config factories have two sources of data:

  • static defaults from the config object
  • runtime overrides from public options

The old implementation only passed the second one through. Once the default config values reach the runtime input again, matchers like ({ marker }) => marker work in real editor flows instead of silently resolving to undefined.

Prevention

  • For factory-based APIs, test both:
    • object-config defaults with no public overrides
    • explicit public overrides
  • When a resolver callback reads a config field like marker, variant, or fence, verify that field exists in the runtime input, not just in the type signature.
  • Add one realistic editor-sequence test whenever an input rule bug only shows up after insertBreak() or another state-changing transform.