Why this matters

Before Claude Code can build a system prompt, it snapshots a few plain-text facts about the repo and the session. The important part is that these memoized helpers are cached for the conversation until their caches are cleared, so Claude Code does not keep rereading the same inputs over and over during the conversation.

Big picture first

This page explains how getGitStatus(), getSystemContext(), and getUserContext() build cached snapshots instead of live-updating state.

getSystemContext() and getUserContext() both return plain objects. Those keys become named context sections later in prompt assembly, so it helps to see the shape before the code that fills them in.

The four fields that matter most here are gitStatus, cacheBreaker, claudeMd, and currentDate.

const MAX_STATUS_CHARS = 2000

export const getGitStatus = memoize(async (): Promise<string | null> => {
  if (process.env.NODE_ENV === 'test') {
    // Avoid cycles in tests
    return null
  }

  const startTime = Date.now()
  logForDiagnosticsNoPII('info', 'git_status_started')

  const isGitStart = Date.now()
  const isGit = await getIsGit()
  logForDiagnosticsNoPII('info', 'git_is_git_check_completed', {
    duration_ms: Date.now() - isGitStart,
    is_git: isGit,
  })

  if (!isGit) {
    logForDiagnosticsNoPII('info', 'git_status_skipped_not_git', {
      duration_ms: Date.now() - startTime,
    })
    return null
  }

  try {
    const gitCmdsStart = Date.now()
    const [branch, mainBranch, status, log, userName] = await Promise.all([
      getBranch(),
      getDefaultBranch(),
      execFileNoThrow(gitExe(), ['--no-optional-locks', 'status', '--short'], {
        preserveOutputOnError: false,
      }).then(({ stdout }) => stdout.trim()),
      execFileNoThrow(
        gitExe(),
        ['--no-optional-locks', 'log', '--oneline', '-n', '5'],
        {
          preserveOutputOnError: false,
        },
      ).then(({ stdout }) => stdout.trim()),
      execFileNoThrow(gitExe(), ['config', 'user.name'], {
        preserveOutputOnError: false,
      }).then(({ stdout }) => stdout.trim()),
    ])

    logForDiagnosticsNoPII('info', 'git_commands_completed', {
      duration_ms: Date.now() - gitCmdsStart,
      status_length: status.length,
    })

    // Check if status exceeds character limit
    const truncatedStatus =
      status.length > MAX_STATUS_CHARS
        ? status.substring(0, MAX_STATUS_CHARS) +
          '\n... (truncated because it exceeds 2k characters. If you need more information, run "git status" using BashTool)'
        : status

    logForDiagnosticsNoPII('info', 'git_status_completed', {
      duration_ms: Date.now() - startTime,
      truncated: status.length > MAX_STATUS_CHARS,
    })

    return [
      `This is the git status at the start of the conversation. Note that this status is a snapshot in time, and will not update during the conversation.`,
      `Current branch: ${branch}`,
      `Main branch (you will usually use this for PRs): ${mainBranch}`,
      ...(userName ? [`Git user: ${userName}`] : []),
      `Status:\n${truncatedStatus || '(clean)'}`,
      `Recent commits:\n${log}`,
    ].join('\n\n')
  } catch (error) {
    logForDiagnosticsNoPII('error', 'git_status_failed', {
      duration_ms: Date.now() - startTime,
    })
    logError(error)
    return null
  }
})

export const getSystemContext = memoize(
  async (): Promise<{
    [k: string]: string
  }> => {
    const startTime = Date.now()
    logForDiagnosticsNoPII('info', 'system_context_started')

    // Skip git status in CCR (unnecessary overhead on resume) or when git instructions are disabled
    const gitStatus =
      isEnvTruthy(process.env.CLAUDE_CODE_REMOTE) ||
      !shouldIncludeGitInstructions()
        ? null
        : await getGitStatus()

    // Include system prompt injection if set (for cache breaking, ant-only)
    const injection = feature('BREAK_CACHE_COMMAND')
      ? getSystemPromptInjection()
      : null

    logForDiagnosticsNoPII('info', 'system_context_completed', {
      duration_ms: Date.now() - startTime,
      has_git_status: gitStatus !== null,
      has_injection: injection !== null,
    })

    return {
      ...(gitStatus && { gitStatus }),
      ...(feature('BREAK_CACHE_COMMAND') && injection
        ? {
            cacheBreaker: `[CACHE_BREAKER: ${injection}]`,
          }
        : {}),
    }
  },
)

export const getUserContext = memoize(
  async (): Promise<{
    [k: string]: string
  }> => {
    const startTime = Date.now()
    logForDiagnosticsNoPII('info', 'user_context_started')

    // CLAUDE_CODE_DISABLE_CLAUDE_MDS: hard off, always.
    // --bare: skip auto-discovery (cwd walk), BUT honor explicit --add-dir.
    // --bare means "skip what I didn't ask for", not "ignore what I asked for".
    const shouldDisableClaudeMd =
      isEnvTruthy(process.env.CLAUDE_CODE_DISABLE_CLAUDE_MDS) ||
      (isBareMode() && getAdditionalDirectoriesForClaudeMd().length === 0)
    // Await the async I/O (readFile/readdir directory walk) so the event
    // loop yields naturally at the first fs.readFile.
    const claudeMd = shouldDisableClaudeMd
      ? null
      : getClaudeMds(filterInjectedMemoryFiles(await getMemoryFiles()))
    // Cache for the auto-mode classifier (yoloClassifier.ts reads this
    // instead of importing claudemd.ts directly, which would create a
    // cycle through permissions/filesystem → permissions → yoloClassifier).
    setCachedClaudeMdContent(claudeMd || null)

    logForDiagnosticsNoPII('info', 'user_context_completed', {
      duration_ms: Date.now() - startTime,
      claudemd_length: claudeMd?.length ?? 0,
      claudemd_disabled: Boolean(shouldDisableClaudeMd),
    })

    return {
      ...(claudeMd && { claudeMd }),
      currentDate: `Today's date is ${getLocalISODate()}.`,
    }
  },
)