Claude Runner

You are working on the CLI execution layer — the bridge between assembled prompts and the claude -p / codex exec CLIs, plus skill file I/O.

Key Concepts

• Stream-JSON protocol (Claude): runClaude() always passes --verbose --output-format stream-json. Output is NDJSON: type: 'result' has final text + usage; type: 'assistant' has text/tool_use blocks; type: 'user' has tool_result blocks.
• JSONL protocol (Codex): runCodex() spawns codex exec --json --sandbox read-only --ephemeral. The --ask-for-approval never flag is conditionally included based on capability detection (see below). Prompt is passed via stdin ('-' placeholder arg) to avoid shell arg length limits. Stdin write happens after event handlers are attached so fast failures are captured. Events: item.completed/item.updated with normalized types.
• Codex capability detection: getCodexExecCapabilities() (internal, cached) runs codex exec --help and checks if --ask-for-approval appears in the help text. Result is cached in module-level codexExecCapabilities variable. If the help check fails (e.g., codex not installed), capabilities default to { supportsAskForApproval: false }. runCodex() only adds --ask-for-approval never when supportsAskForApproval is true.
• Unified routing: runLLM(prompt, options, backendId) is the shared entry point — dispatches to runClaude() or runCodex() based on backendId. Exported from runner.js so command handlers no longer need local routing helpers.
• Codex internals (private): normalizeCodexItemType() converts PascalCase/kebab-case to snake_case. collectCodexText() recursively extracts text from nested event content. Both are internal to runner.js.
• Prompt templating: loadPrompt(name, vars) resolves {{partial-name}} from src/prompts/partials/ first, then substitutes {{varName}} from vars. Target-specific vars (skillsDir, skillFilename, instructionsFile, configDir) are passed by command handlers.
• File output parsing: Primary: <file path="...">content</file> XML tags. Fallback: <!-- file: path --> comment markers. parseFileOutput(output, allowedPaths) accepts optional { dirPrefixes, exactFiles } to override default allowed paths.
• Path sanitization: sanitizePath(rawPath, allowedPaths) (internal) blocks .. traversal, absolute paths. Defaults: .claude/ prefix + CLAUDE.md exact. Multi-target callers pass expanded allowed paths via getAllowedPaths() from target.js.
• Validation: validateSkillFiles() checks for truncation (XML tag collisions), missing frontmatter, missing sections, bad file path references.
• Skill rules generation: extractRulesFromSkills() reads all skills via skill-reader.js, produces skill-rules.json (v2.0) with file patterns, keywords, and intent patterns.
• Domain patterns: generateDomainPatterns() converts file patterns to bash detect_skill_domain() function using BEGIN/END markers.
• Trigger parsing precedence: parseTriggersFrontmatter(content) returns { filePatterns, keywords, alwaysActivate } parsed from a triggers: block in YAML frontmatter (supports block lists, inline arrays, and alwaysActivate: true for the base skill); returns null when no triggers: key exists. parseActivationPatterns and parseKeywords prefer this frontmatter when present and fall back to legacy ## Activation / Keywords: line parsing for older skills.
• Settings merge: mergeSettings() merges aspens hook config into existing settings.json. Detects aspens-managed hooks by ASPENS_HOOK_MARKERS (skill-activation-prompt, graph-context-prompt, post-tool-use-tracker, save-tokens-statusline, save-tokens-prompt-guard, save-tokens-precompact). Also handles statusLine merging — replaces existing statusLine only if the current one is aspens-managed (detected by isAspensHook), preserving user-custom statusLine configs. After merging hooks, dedupeAspensHookEntries() removes duplicate aspens-managed entries per event type.
• Directory-scoped writes: writeTransformedFiles() handles files outside .claude/ (e.g., src/billing/AGENTS.md) with explicit path allowlist — only CLAUDE.md, AGENTS.md exact files and .claude/, .agents/, .codex/ prefixes are permitted.
• findSkillFiles matching: Only matches the exact skillFilename (e.g., skill.md or SKILL.md), not arbitrary .md files in the skills directory.

Critical Rules

• Both --verbose and --output-format stream-json are required for Claude — omitting either breaks stream parsing.
• Codex uses --json --sandbox read-only --ephemeral — --sandbox read-only restricts filesystem access, --ephemeral avoids persisting conversation. --ask-for-approval never is added only if getCodexExecCapabilities() confirms support. Prompt goes via stdin, not as a CLI arg.
• Codex stdin write order matters — event handlers (stdout, stderr, close, error) must be attached before writing to stdin, so fast failures are captured.
• Path sanitization is non-negotiable — sanitizePath() blocks .. traversal, absolute paths, and any path not in the allowed set.
• Prompt partials resolve before variables — {{skill-format}} resolves to partials/skill-format.md first. If no file, falls through to variable substitution.
• Timeout resolution: resolveTimeout(flagValue, fallbackSeconds) — --timeout flag wins, then ASPENS_TIMEOUT env, then caller-provided fallback. Size-based defaults (small: 120s, medium: 300s, large: 600s, very-large: 900s) are set by command handlers, not runner.
• Disk writes are sanitized — writeSkillFiles and writeTransformedFiles pass every payload through sanitizePublishedContent so forbidden blocks (## Activation, ## Key Files, hub/cluster/hotspot tables outside code-map.md) cannot leak to disk even if an earlier stage missed them.
• mergeSettings preserves non-aspens hooks and statusLine — identifies aspens hooks by ASPENS_HOOK_MARKERS (now includes save-tokens markers), replaces matching entries, preserves everything else. StatusLine only replaced if current one is aspens-managed. Post-merge deduplication ensures no duplicate aspens entries accumulate.
• Debug mode: Set ASPENS_DEBUG=1 to dump raw stream-json to $TMPDIR/aspens-debug-stream.json (Claude) or $TMPDIR/aspens-debug-codex-stream.json (Codex). Codex also logs exit code and output length to stderr.

Last Updated: 2026-05-11