The context system assembles the environment information that gets injected into the system prompt at the start of each conversation. It is defined in src/context.ts and provides two memoized functions: getSystemContext() for repository/environment state and getUserContext() for user-specific configuration like CLAUDE.md files.

System Context

getSystemContext() gathers environment information that gives the model awareness of the current project state.

export const getSystemContext = memoize(
  async (): Promise<{ [k: string]: string }> => {
    const gitStatus = // ...fetch git info
    const injection = // ...cache breaker (ant-only)

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

Git Status

When the project is a git repository and git instructions are not disabled, getSystemContext calls getGitStatus() which runs several git commands in parallel:

The git status is prefixed with a note that it is a snapshot from conversation start and will not update during the conversation. If the status exceeds 2000 characters, it is truncated with a message suggesting the model use BashTool for the full output.

const [branch, mainBranch, status, log, userName] = await Promise.all([
  getBranch(),
  getDefaultBranch(),
  execFileNoThrow(gitExe(), ['status', '--short'], ...),
  execFileNoThrow(gitExe(), ['log', '--oneline', '-n', '5'], ...),
  execFileNoThrow(gitExe(), ['config', 'user.name'], ...),
])

Cache Breaker

Behind the BREAK_CACHE_COMMAND feature flag, an internal-only system prompt injection can be set via setSystemPromptInjection(). This is used for ephemeral debugging and forces cache invalidation on the API side.

Skipped Scenarios

Git status is skipped in two cases:

• CCR (Claude Code Remote): the CLAUDE_CODE_REMOTE env var is set, avoiding unnecessary overhead on session resume
• Git instructions disabled: the user has opted out via shouldIncludeGitInstructions() settings

User Context

getUserContext() loads user-facing configuration, primarily CLAUDE.md files and the current date.

export const getUserContext = memoize(
  async (): Promise<{ [k: string]: string }> => {
    const claudeMd = shouldDisableClaudeMd
      ? null
      : getClaudeMds(filterInjectedMemoryFiles(await getMemoryFiles()))

    setCachedClaudeMdContent(claudeMd || null)

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

CLAUDE.md Loading

The CLAUDE.md loading pipeline:

1. getMemoryFiles(): discovers CLAUDE.md files from the directory hierarchy (home directory, project root, current directory)
2. filterInjectedMemoryFiles(): removes files that were injected by other mechanisms
3. getClaudeMds(): reads and concatenates the file contents

Disable Conditions

CLAUDE.md loading is disabled when:

• CLAUDE_CODE_DISABLE_CLAUDE_MDS env var is truthy: hard off, always
• --bare mode is active AND no --add-dir directories are specified. Bare mode means "skip what I didn't ask for," but honors explicit --add-dir flags

Caching for Classifier

The loaded CLAUDE.md content is cached via setCachedClaudeMdContent() for use by the auto-mode classifier (yoloClassifier.ts). This breaks a circular dependency: the classifier needs CLAUDE.md content, but importing the claudemd module directly would create a cycle through permissions/filesystem -> permissions -> yoloClassifier.

Memoization Strategy

Both context functions use lodash memoize() with no arguments, meaning they compute once per process lifetime and cache the result. This is appropriate because:

• Git status and CLAUDE.md content represent the state at conversation start
• The model is told explicitly that git status is a snapshot and will not update
• For long-running sessions, the cache can be cleared via getUserContext.cache.clear() and getSystemContext.cache.clear()

The setSystemPromptInjection() function clears both caches immediately when the injection value changes, ensuring the cache breaker takes effect on the next query.

Context Injection Flow

The context values flow into the system prompt through the query pipeline:

getSystemContext()  --->  appendSystemContext()   --->  System Prompt
getUserContext()    --->  prependUserContext()     --->  (sent to API)

Diagnostic Logging

Both context functions emit structured diagnostic logs via logForDiagnosticsNoPII:

• system_context_started / system_context_completed with duration and content flags
• user_context_started / user_context_completed with duration and content length
• git_status_started / git_status_completed with truncation info
• git_commands_completed with individual command timings

These logs contain no PII (personally identifiable information) and are used for performance monitoring and debugging context assembly latency.