Mere

A workbook format for apps. The file is the app.

A .mp.html file contains screens, state, behavior, theme, and data. Open it — it runs. Send it — it travels. No server, no account, no build step.

→ docs.mere.fyi

What it looks like

<workbook theme="proton-mail">

  <state>
    <value name="tasks" type="list" value="[]"></value>
    <value name="new-task" type="text" value=""></value>
  </state>

  <computed>
    <value name="task-count" from="tasks" op="count"></value>
  </computed>

  <actions>
    <action name="add-task">
      add-to tasks title @new-task
      clear new-task
    </action>
  </actions>

  <screen name="home">
    <header>
      <heading>Tasks</heading>
      <badge @task-count></badge>
    </header>
    <field ~new-task placeholder="New task…"></field>
    <button !add-task>Add</button>
    <card-list @tasks>
      <card><heading @item.title></heading></card>
    </card-list>
  </screen>

</workbook>

Save as tasks.mp.html. Double-click. It runs.

Three sigils bind. One annotates.

| Sigil | Name | Example | Meaning | |-------|------|---------|---------| | @ | read | <heading @title> | One-way binding from state. On list containers, iterates the array. | | ~ | two-way | <field ~email> | Bidirectional sync between input and state. | | ! | action | <button !submit> | Invokes a named action on click. |

Each takes a bare identifier. ? is not a fourth binding — it takes a quoted string, binds to nothing, and is inert at runtime:

| Marker | Example | Meaning | |--------|---------|---------| | ? | <screen ?"Show inbox"> | Natural-language intent for a generator. Ignored when the workbook runs. |

40 elements. No HTML passthrough.

Every element has a specific role. The vocabulary is closed by design — bounded enough for AI to generate reliably, expressive enough for real apps.

Installation

npm install -g @semanticintent/mere-cli

CLI

mere check tasks.mp.html     # validate — exit 0/1/2
mere check *.mp.html          # validate multiple, summary line
mere pack tasks.mp.html        # inline the runtime — self-contained .packed.mp.html
mere dev tasks.mp.html         # local server — check-on-save, live reload
mere diff old.mp.html new.mp.html   # structural diff — screens/state/computed/actions
mere validate tasks.packed.mp.html  # confirm a packed file matches its embedded source
mere schema                   # print element registry
mere schema --json            # machine-readable JSON

4 themes

| Theme | Character | |---|---| | classic-light | Neutral baseline. Clean cards, comfortable spacing. The default. | | proton-mail | Purple accent, underline tabs, 14px base type. | | brutalist | Zero radius, 3px black borders, inverted header, red accent. | | warm-brutalist | Parchment and ink, restrained indigo accent, generous radius — brutalist’s warmer sibling. |

Persistence

Add persist to any state value — saved to OPFS (localStorage fallback):

<value name="notes" type="list" value="[]" persist></value>

Why not just HTML?

HTML gives you the substrate. Mere gives you the contract.

Raw HTML has no opinions about state, data flow, or actions. Infinite choices produce inconsistent output — especially for AI generation. Mere's bounded vocabulary, explicit sigils, and text-based action syntax mean a model can produce a valid workbook reliably, because there are no escape hatches and no ambiguity.

The file runs anywhere HTML runs. Forever. No framework lock-in.

Examples

See examples/ for ready-to-open workbooks. Full live examples at docs.mere.fyi/examples.

Docs

• docs/concept.md — what Mere is and why
• docs/spec.md — full language specification
• docs/roadmap.md — milestones and open questions

License

MIT — see LICENSE.