xcsym Reference (iOS/macOS Crash Symbolication)

Complete reference for xcsym, the Axiom-bundled CLI that symbolicates .ips (v1/v2), MetricKit (MXCrashDiagnostic), Apple's legacy .crash text, and Xcode Organizer .xccrashpoint bundles. Auto-detects format, discovers dSYMs, symbolicates via atos, categorizes crashes into a pattern_tag, and reports UUID/arch mismatches per image.

When to Use This Reference

Use this reference when:

• Looking up xcsym crash / verify / resolve / find-dsym / list-dsyms / anonymize subcommand flags
• Checking the JSON output schema emitted by crash (tool, version, format, input, crash, images, images_summary, warnings, size_warning)
• Interpreting an exit code (0 / 1 usage / 2 input or main-dSYM missing / 3 UUID mismatch / 4 arch mismatch / 5 tool error / 6 timeout / 7 partial match / 8 output error)
• Mapping a pattern_tag to its rule ID, confidence, and signal
• Understanding the dSYM discovery order (explicit-by-UUID → explicit paths → cache → Spotlight → Archives → DerivedData → Frameworks → Downloads → Toolchain → env paths)
• Handling .xccrashpoint bundles (--filter, --prefer-locally-symbolicated, empty_bundle vs unsupported_format)
• Reading the routing JSON xcsym emits on hang input (bug_type=298) or unsupported formats
• Configuring --format=summary / standard / full and the tier-aware size warnings
• Scrubbing a crash for fixture use (what anonymize scrubs vs preserves — dSYM UUIDs are preserved so anonymized fixtures still symbolicate)

Example Prompts

• "What does xcsym crash return?"
• "What pattern tags can xcsym emit?"
• "Why did xcsym exit with code 3?"
• "How does xcsym find dSYMs?"
• "What does anonymize preserve so the fixture still symbolicates?"
• "How do I handle an .xccrashpoint bundle with multiple builds?"
• "What's the difference between crash and verify exit codes?"

What's Covered

• Invocation — xcsym is on PATH as a bare command (Claude Code 2.1.91+ resolves plugin bin/ entries automatically); no prefix or path lookup needed
• crash subcommand — full pipeline (parse → discover dSYMs → symbolicate → categorize → emit JSON); --format, --from-metrickit, --dsym, --dsym-paths, --no-symbolicate, --no-cache, --no-spotlight, --output, stdin support, .xccrashpoint flags
• verify subcommand — per-image UUID/arch match diagnostics, different exit-code semantics than crash
• resolve subcommand — single-address resolution via atos against an explicit dSYM
• find-dsym subcommand — UUID-driven dSYM lookup across the full discovery chain
• list-dsyms subcommand — inventory by source (Archives, DerivedData, downloads, toolchain, frameworks, env, all)
• anonymize subcommand — what it scrubs (bundle IDs, process names, user paths, IPs, device names, account IDs, foreign UUIDs in freeform strings) versus preserves (dSYM UUIDs, thread names, library identifiers, structural fields)
• Output schema — top-level JSON shape with pattern_tag, pattern_confidence, pattern_rule_id, pattern_reason, crashed_thread, images matched/mismatched/missing
• Format tiers — summary (~2 KB / warn 4 KB), standard (~12 KB / warn 50 KB), full (warn 100 KB)
• Exit codes — shared codes (0/1/5/6/8) plus subcommand-specific symbolication codes (2/3/4/7), including the crash vs verify divergence on code 7
• Pattern tag catalog — all 19 tags Apple has surfaced via xcsym (swift_forced_unwrap, swift_concurrency_violation, swift_fatal_error, zombie_or_heap_corruption, stack_overflow, bad_memory_access, illegal_instruction, exc_guard, objc_exception, main_thread_checker_violation, abort, watchdog_termination, user_force_quit, background_task_expired, data_protection_violation, code_signing_killed, jetsam_oom, cpu_resource_fatal, swiftui_update_loop, unclassified) with their rule IDs and confidence levels
• dSYM discovery order — ten-step chain with the XCSYM_FRAMEWORK_SCAN_TIMEOUT and XCSYM_DSYM_PATHS environment-variable hooks
• Hang and unsupported input routing — JSON reject shapes (hang_report, unsupported_format, empty_bundle) so agents route on the error field instead of scraping stderr
• Troubleshooting table — symptom → cause → fix for the common exit codes and bundle errors

Documentation Scope

This page documents the xcsym-ref reference skill — the bundled Axiom CLI for static crash analysis.

• For end-to-end usage guidance, see Crash Symbolication (xcsym)
• For the agent that interprets xcsym JSON with pattern → fix guidance, see the crash-analyzer agent
• For the /axiom:analyze-crash command wrapper, see /axiom:analyze-crash
• For hang .ips files (bug_type=298), xcsym rejects them by design — see Hang Diagnostics instead
• For live console capture (the runtime counterpart to xcsym's post-mortem analysis), see Console Capture (xclog)
• For TestFlight crash triage workflows that run xcsym first, see TestFlight Triage