companion by MaryCache: Claude Code mod code and design

What it does

Draws a pane, a band above the prompt
Adds /board
Watches tool calls and can refuse them
Hooks prompt.submit, session.measure, session.start, skill.prompt and 1 more
Starts processes

Good points

No network calls
Written in TypeScript
Has a desktop-specific branch
Handles errors

Code to start from

Two kinds: a starter modscode writes from the design above, and the lines of the mod's own code that draw it.

Starter (register.tsx)

import type { Register } from 'claude-code'

// Drawn like companion by MaryCache (pane, band, toast), as modscode read it from the mod's code:
// https://modscode.com/gallery/marycache-companion/
// Written by modscode from that reading, not copied from the mod: use it as you like.
// Each value below stands for one the mod works out at run time; put in your own.
export const register: Register = on => {
  // the pane: open it with $.ui.open({ id: 'my-pane', title: "‹paneTitle›" })
  on('ui.render', { component: 'Pane', requestId: 'my-pane' }, async ($, e) => {
    const { Box, Text, Button } = $.ui.resolve(e)
    const label = '…'
    const label2 = '…'
    const label3 = '…'
    const usageHeading = '…'
    const usageEmpty = '…'
    const label4 = '…'
    const filled = '…'
    const part = '…'
    const percent = '…'
    const usageUntil = '…'
    const label5 = '…'
    const filled2 = '…'
    const part2 = '…'
    const label6 = '…'
    const filled3 = '…'
    const part3 = '…'
    const folderLabel = '…'
    const shortenHome = '…'
    const lookHeading = '…'
    const title = '…'
    const open = '…'
    const done = '…'
    const note = '…'
    const target = '…'
    const title2 = '…'
    const target2 = '…'
    const title3 = '…'
    const target3 = '…'
    const sectionInProgress = '…'
    const length = '…'
    const sectionEmpty = '…'
    const title4 = '…'
    const tags = '…'
    const title5 = '…'
    const tags2 = '…'
    const title6 = '…'
    const tags3 = '…'
    const sectionBlocked = '…'
    const length2 = '…'
    const sectionEmpty2 = '…'
    const title7 = '…'
    const tags4 = '…'
    const title8 = '…'
    const tags5 = '…'
    const title9 = '…'
    const tags6 = '…'
    const sectionReview = '…'
    const length3 = '…'
    const sectionEmpty3 = '…'
    const title10 = '…'
    const tags7 = '…'
    const title11 = '…'
    const tags8 = '…'
    const title12 = '…'
    const tags9 = '…'
    const readAt = '…'
    const reload = '…'
    return (
      <Box flexDirection="column">
        <Box flexDirection="column" flexGrow={1}>
          <Box flexDirection="column">
            <Box marginBottom={1}>
              <Box marginRight={1}>
                <Text bold color="#C8664A">
                  [
                  {label}
                  ]
                </Text>
              </Box>
              <Box marginRight={1}>
                <Text bold color="#C8664A">
                  [
                  {label2}
                  ]
                </Text>
              </Box>
              <Box marginRight={1}>
                <Text bold color="#C8664A">
                  [
                  {label3}
                  ]
                </Text>
              </Box>
            </Box>
            <Box flexDirection="column" marginBottom={1}>
              <Text bold color="#C8664A">
                {usageHeading}
              </Text>
              <Text dimColor>
                {usageEmpty}
              </Text>
              <Text wrap="truncate-end">
                {label4}
                {" "}
                <Text>
                  {filled}
                </Text>
                <Text backgroundColor="#4A4440">
                  {part}
                </Text>
                <Text color="#4A4440">
                  ████████
                </Text>
                {" "}
                {`${percent}%`}
                <Text dimColor>
                  {`  ${usageUntil}`}
                </Text>
              </Text>
              <Text wrap="truncate-end">
                {label5}
                {" "}
                <Text>
                  {filled2}
                </Text>
                <Text backgroundColor="#4A4440">
                  {part2}
                </Text>
                <Text color="#4A4440">
                  ████████
                </Text>
                {" "}
                {`${percent}%`}
                <Text dimColor>
                  {`  ${usageUntil}`}
                </Text>
              </Text>
              <Text wrap="truncate-end">
                {label6}
                {" "}
                <Text>
                  {filled3}
                </Text>
                <Text backgroundColor="#4A4440">
                  {part3}
                </Text>
                <Text color="#4A4440">
                  ████████
                </Text>
                {" "}
                {`${percent}%`}
                <Text dimColor>
                  {`  ${usageUntil}`}
                </Text>
              </Text>
            </Box>
            <Box marginBottom={1}>
              <Text dimColor>
                {folderLabel}
              </Text>
              <Button label={`${shortenHome}`} />
            </Box>
            <Box flexDirection="column" marginBottom={1}>
              <Text bold color="#C8664A">
                {lookHeading}
              </Text>
              <Box flexDirection="column">
                <Box>
                  <Text wrap="truncate-end">
                    ・
                    {title}
                    {" "}
                  </Text>
                  <Button label={`${open}`} />
                  <Text>
                    {" "}
                  </Text>
                  <Button label={`${done}`} />
                </Box>
                <Text dimColor wrap="truncate-start">
                  {"  "}
                  {`${note} · `}
                  {target}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Box>
                  <Text wrap="truncate-end">
                    ・
                    {title2}
                    {" "}
                  </Text>
                  <Button label={`${open}`} />
                  <Text>
                    {" "}
                  </Text>
                  <Button label={`${done}`} />
                </Box>
                <Text dimColor wrap="truncate-start">
                  {"  "}
                  {`${note} · `}
                  {target2}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Box>
                  <Text wrap="truncate-end">
                    ・
                    {title3}
                    {" "}
                  </Text>
                  <Button label={`${open}`} />
                  <Text>
                    {" "}
                  </Text>
                  <Button label={`${done}`} />
                </Box>
                <Text dimColor wrap="truncate-start">
                  {"  "}
                  {`${note} · `}
                  {target3}
                </Text>
              </Box>
            </Box>
            <Box flexDirection="column" marginBottom={1}>
              <Text bold color="#C8664A">
                {sectionInProgress}
                {" "}
                {length}
              </Text>
              <Text dimColor>
                {sectionEmpty}
              </Text>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title4}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title5}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags2}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title6}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags3}
                </Text>
              </Box>
            </Box>
            <Box flexDirection="column" marginBottom={1}>
              <Text bold color="#C8664A">
                {sectionBlocked}
                {" "}
                {length2}
              </Text>
              <Text dimColor>
                {sectionEmpty2}
              </Text>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title7}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags4}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title8}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags5}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title9}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags6}
                </Text>
              </Box>
            </Box>
            <Box flexDirection="column" marginBottom={1}>
              <Text bold color="#C8664A">
                {sectionReview}
                {" "}
                {length3}
              </Text>
              <Text dimColor>
                {sectionEmpty3}
              </Text>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title10}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags7}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title11}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags8}
                </Text>
              </Box>
              <Box flexDirection="column">
                <Text wrap="truncate-end">
                  ・
                  {title12}
                </Text>
                <Text dimColor wrap="truncate-end">
                  {"  "}
                  {tags9}
                </Text>
              </Box>
            </Box>
            <Box>
              <Text dimColor>
                {readAt}
              </Text>
              <Button label={`${reload}`} />
            </Box>
          </Box>
        </Box>
      </Box>
    )
  })

  // the band above the prompt; what else goes there is drawn under it
  on('ui.render', { component: 'AbovePrompt' }, async ($, e, next) => {
    const { Box, Text, Button } = $.ui.resolve(e)
    const name = '…'
    const bandLine = '…'
    const bandCounts = '…'
    const bandBoardButton = '…'
    const bandHideButton = '…'
    return (
      <Box flexDirection="column">
        <Box>
          <Text color="#C8664A">
            {"◦ "}
            {name}
            {" "}
          </Text>
          <Text dimColor wrap="truncate-end">
            {bandLine}
            {bandCounts}
          </Text>
          <Button label={`${bandBoardButton}`} />
          <Text>
            {" "}
          </Text>
          <Button label={`${bandHideButton}`} />
        </Box>
        {await next(e)}
      </Box>
    )
  })
}

The mod's own code

Its licence text was not found at the commit read, so only the places in the source are linked.

What its code calls

runs programswrites filesenv varstool calls

What its code shows

Read from the source at commit d4ae7e0b20fc on 2026-10-06. The first group decides whether a mod is listed; the rest is for you to weigh. A later commit is not read until the next crawl.

Decides the listing: code you can check
Entry read	Every module hooks/hooks.json names was read.plugins/companion/hooks/register.tsx
Parses	Every file parses as TypeScript or JavaScript.18 files parsed
All its code is in the mod	Every import is a file of the mod or the engine's own module; no packages, no require.all its code is in the mod
Readable	No minified lines, no eval or new Function, no import of a computed path, no encoded blobs.no minified code, no eval, no encoded blobs
Calls in the open	Network and programs are reached as $.http.fetch and $.process.run in place, never passed around.every call outside goes through $ in the open
For you to weigh before installing
Where it draws	The terminal, the desktop app, both, or nothing (hooks only: a guard or a prompt rewriter), as its code says. Shown, never a reason to leave a mod out.draws in the terminal and the desktop app, the same in both
Install line	Whether its repository's own .claude-plugin/marketplace.json lists it, so it installs from that marketplace with the lines on its page.listed in its repository's .claude-plugin/marketplace.json: installs from there
Programs on Windows	Whether every program it starts through $.process exists on Windows (tail, date, open, osascript, /usr/… do not).plugins/companion/hooks/register.tsx:116 mv (not on Windows); plugins/companion/hooks/register.tsx:122 rm (not on Windows); plugins/companion/hooks/register.tsx:184 which (not on Windows); plugins/companion/hooks/register.tsx:241 uname (not on Windows)
Network	Whether every fetch names its https host in the code.no network
Programs	Whether every program it starts is named in the code and is not a shell, an interpreter or a network tool.plugins/companion/hooks/register.tsx:269 a program named at run time
Reads and sends	Whether it both reads files or environment variables and reaches the network.reaches no network
Keys in the source	Whether the source holds what looks like an API key or a private key.no keys in the source
Licence	An open licence (MIT, Apache-2.0, BSD, ISC, Unlicense, 0BSD, CC0) with its text lets modscode show its code; otherwise the code is linked.no licence

This is a reading of the code text, not a security review: it does not run the mod, and it cannot see what a program the mod starts does. The check before installing is yours. How mods are chosen

Install it

Check it yourself before you install it. Mods run unsandboxed, with your permissions, and modscode does not vouch for what this code does. Read the code below (or run claude plugin validate . in its folder), weigh what it reaches, and install the commit you read.

Its repository is its marketplace. Add that marketplace (in the terminal with these commands, or in the desktop app's plugin settings) and install the mod from it:

/plugin marketplace add MaryCache/claude-code-companion-mod

/plugin install companion@claude-code-companion-mod

This installs the marketplace's latest commit, which may not be the one read here (d4ae7e0b20fc). Compare them before you install.

Ask Claude about it

With the modscode connector added, Claude can read this design, what its code reaches and its code, and build on them. Ask it like this:

Read the modscode design "marycache-companion" with its code and make me a pane like it

Search them from Claude: the MCP connector