Random Live Region Message Sequence Generator

Description

Generate grouped synthetic status updates under supplied live/atomic policies, retaining lexical attributes and a declared coalescing convention rather than predicting assistive-technology announcements.

An interface fixture makes content and state explicit so a consumer can test a rendering or interaction. Literal labels, modeled states, and calculated geometry remain separate from what a browser or assistive technology actually displays or announces.

When to use this tool

Use this generator to create reproducible live region message sequence cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.

How to use the tool and how it works

Supply messages, count, groupSize, policy, atomic in the field shapes below. Set seed when you need an explicit replay.
Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
Read updates, groups, modeledAnnouncements, regionTag, parsed. Use the conventions below and keep answer-bearing fields separate when presenting an exercise.

Sample messages, chunk them into update groups, and return a simplified announcement model: none for off, the last message per group for atomic, otherwise all messages. Serialize and parse the region's aria-live and aria-atomic attributes.^[1]

Delegated operations used for this result: chunk. Their calculation or parsing conventions apply to the corresponding result fields.^[2]

Input field	Meaning and units	Accepted input
messages	Messages	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 128.; minimum items 1; maximum items 32.
count	Requested count; the mechanics explain whether one draw expands into several returned records.	Required. Safe integer; minimum 1; maximum 32.
groupSize	Group Size	Required. Safe integer; minimum 1; maximum 32.
policy	Policy	Required. Text; one of "off", "polite", "assertive".
atomic	Atomic	Required. Boolean.
seed	Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed.	Optional. Safe integer.

Output field	Interpretation	Returned shape
updates	Updates	Required. Array of Object; no unknown keys.; minimum items 1; maximum items 32.
updates[].tick	Tick	Required. Safe integer; minimum 1; maximum 32.
updates[].text	Text	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 128.
groups	Groups	Required. Array of Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 128.; minimum items 1; maximum items 32.; minimum items 1; maximum items 32.
modeledAnnouncements	Modeled Announcements	Required. Array of Text; minimum UTF-16 length 1; maximum UTF-16 length 128.; minimum items 0; maximum items 32.
regionTag	Region Tag	Required. Text; maximum UTF-16 length 131072.
parsed	Parsed	Required. Object; no unknown keys.
parsed.name	Name	Required. Text; maximum UTF-16 length 256.
parsed.attributes	Attributes	Required. Array of Object; no unknown keys.; minimum items 0; maximum items 16.
parsed.attributes[].name	Name	Required. Text; maximum UTF-16 length 256.
parsed.attributes[].value	Value	Required. Text; maximum UTF-16 length 2048.
randomness	Replay metadata: source is seed or context; seed is the normalized 32-bit seed or null for a context source.	Required. Object; no unknown keys.
randomness.seed	Optional numeric replay seed; normalization and precedence are explained below.	Required. Safe integer. or Null.
randomness.source	Source	Required. Text; one of "context", "seed".

An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.

json

{
  "input": {
    "messages": [
      "Saved",
      "Queued"
    ],
    "count": 3,
    "groupSize": 2,
    "policy": "polite",
    "atomic": true,
    "seed": 42
  },
  "output": {
    "updates": [
      {
        "tick": 1,
        "text": "Queued"
      },
      {
        "tick": 2,
        "text": "Saved"
      },
      {
        "tick": 3,
        "text": "Queued"
      }
    ],
    "groups": [
      [
        "Queued",
        "Saved"
      ],
      [
        "Queued"
      ]
    ],
    "modeledAnnouncements": [
      "Saved",
      "Queued"
    ],
    "regionTag": "<div aria-live=\"polite\" aria-atomic=\"true\">",
    "parsed": {
      "name": "div",
      "attributes": [
        {
          "name": "aria-live",
          "value": "polite"
        },
        {
          "name": "aria-atomic",
          "value": "true"
        }
      ]
    },
    "randomness": {
      "seed": 42,
      "source": "seed"
    }
  }
}

Limitations and assumptions

modeledAnnouncements is an explicit fixture convention, not predicted screen-reader behavior. Actual announcements depend on assistive technology, DOM changes, timing, and user settings.
A replay requires the same complete input and implementation. Randomized construction does not guarantee uniform coverage of every feasible output; finite samples can repeat unless a distinct-selection rule is explicitly stated.
The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.

Alternative or Complementary methods

For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.

References

Tool behavior and example: Random Live Region Message Sequence Generator — tool.io
Calculation or validation: list/chunk — tool.io

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