ReferenceError: getCurrentOutputStyleName is not defined on session start/resume (regression in 2.1.193, still in 2.1.195)

Solid root-cause writeup — the free getCurrentOutputStyleName identifier with no definition in the telemetry/context-payload builder matches the all-React-render stack on startup. (I'm on 2.1.179 so I can't reproduce 2.1.193/195 myself; the notes below are the things I can verify, framed as such.)
Three things worth adding for anyone landing here in a panic, since "every session start crashes" reads like a total lockout:
1. Your sessions are not lost — this is purely the binary. The crash is in a render-path telemetry builder, not in storage. Your conversation history lives on disk as ~/.claude/projects/<encoded-cwd>/<uuid>.jsonl and is untouched by this bug (verified on my own install: the transcripts are plain .jsonl files that exist independently of the running version). So the rollback fully recovers you, and claude --resume brings the old sessions right back. Nothing was deleted.
2. Don't "fix" it by reinstalling from scratch. Because the only broken thing is the compiled binary, a clean reinstall / deleting ~/.claude / clearing config buys you nothing and risks losing your settings.json, MCP servers, and custom config for no reason. Roll the binary back, leave config alone.
3. Rollback gotchas (so the workaround doesn't silently no-op):

• Before ln -sfn ... 2.1.191 ..., confirm that version is actually cached: ls ~/.local/share/claude/versions/. If 2.1.191 isn't in there, the symlink points at a non-existent path and you get a different breakage instead of a fix. Pick the newest good version that is present (anything ≤ 2.1.191 by their evidence).
• The native-installer symlink + DISABLE_AUTOUPDATER=1 advice only applies to native-installer users. If you installed via npm (which claude resolves into a node .../bin/claude), the symlink trick doesn't apply — pin instead with npm install -g @anthropic-ai/claude-code@<last-good-version> and avoid @latest / claude update until a fixed build ships.
• Set DISABLE_AUTOUPDATER (or pin the npm version) before the next launch, otherwise an auto-update can quietly put you back on the broken build.

Net: acute and total (no session starts), but non-destructive — history and config are safe, and the rollback is a clean recovery rather than a rebuild.

I have this issue also.

Confirming the same crash on Windows 11 (native installer), so this isn't macOS-specific.

• Claude Code 2.1.195 (and 2.1.193) crash with ReferenceError: getCurrentOutputStyleName is not defined on claude --resume; 2.1.191 is fine.
• Same evidence in the bundled binary: the symbol appears only as the call site outputStyle:getCurrentOutputStyleName() with no definition. Occurrence counts in the cached native builds: 2.1.191 → 0, 2.1.193 → 1 (call, no def), 2.1.195 → 1 (call, no def).
• Path in my stack trace: B:/~BUN/root/src/entrypoints/cli.js.
• Workaround confirmed working on Windows: roll ~/.local/bin/claude.exe back to the cached versions/2.1.191 build and set DISABLE_AUTOUPDATER=1.

Env: Windows 11 Pro (10.0.26200), x64, native installer.

Confirmed on Linux (kernel 7.1.1-tigerlake, x86_64), Claude Code 2.1.195.

Same error, same stack trace as described.

Additional workaround (no downgrade needed): print mode bypasses the crashing render path entirely:

claude -p --resume <session-id> "your message"

Tested on a session originally created with 2.1.178–2.1.186 — resumes cleanly with -p, crashes with interactive mode.

Confirmed still broken in 2.1.197 (Linux, x86_64, kernel 7.1.1-tigerlake)

Tested by triggering the native installer update from 2.1.195 → 2.1.197:

~/.local/share/claude/versions/2.1.195 update
# Successfully updated from 2.1.195 to version 2.1.197

Symbol occurrence count in each binary (grep -oa "getCurrentOutputStyleName" <binary> | wc -l):

| Version | Occurrences | Status |
|---------|-------------|--------|
| 2.1.190 | 0 | ✅ OK |
| 2.1.195 | 2 | ❌ crashes |
| 2.1.197 | 2 | ❌ crashes |

Context in 2.1.197 bundle (identical to 2.1.195):

activeAgents),account:INt(),outputStyle:getCurrentOutputStyleName(),mcpServers:...

Call site present, no definition — same root cause, not fixed in 2.1.197.

Workaround still required: pin to 2.1.190 or use claude -p (print mode).

Binary patch workaround (works on Linux/macOS/Windows-WSL, no downgrade needed)

Since the bug persists in 2.1.197, here's a surgical binary patch that fixes it without rolling back.

Root cause (confirmed)

The Bun bundle embeds JS uncompressed. getCurrentOutputStyleName() appears as a 27-byte literal call with no definition. Pre-2.1.193 the field didn't exist, so returning undefined is semantically equivalent.

Patch

Replace the 27-byte call with (void 0) + 19 spaces (same byte count → no offset shift, valid JS):

#!/usr/bin/env python3
import sys, os

NEEDLE      = b'getCurrentOutputStyleName()'   # 27 bytes
REPLACEMENT = b'(void 0)                   '   # 27 bytes

binary  = sys.argv[1]  # e.g. ~/.local/share/claude/versions/2.1.197
patched = binary + '-patched'

data = bytearray(open(binary, 'rb').read())
pos  = data.find(NEEDLE)
assert pos != -1, "needle not found — bug may already be fixed"
data[pos:pos+len(NEEDLE)] = REPLACEMENT
open(patched, 'wb').write(data)
os.chmod(patched, 0o755)
print(f"Patched → {patched}  (offset {pos})")

python3 patch.py ~/.local/share/claude/versions/2.1.197
# Patched → ...2.1.197-patched  (offset 242501161)

Auto-patch wrapper (survives future updates, self-disables when fixed)

Put this in a directory that precedes ~/.local/bin in $PATH (e.g. ~/.claude/scripts/claude):

#!/bin/bash
# Workaround for bug #71980 — remove once fixed upstream
NEEDLE='getCurrentOutputStyleName()'
REPLACEMENT='(void 0)                   '   # 27 bytes — same length as NEEDLE

has_bug() {
    # Bug = call present AND no definition
    # When Anthropic fixes it, they add a definition (getCurrentOutputStyleName=...)
    # so the second grep returns true and has_bug returns false → wrapper becomes a no-op
    grep -qoa 'getCurrentOutputStyleName(' "$1" 2>/dev/null && \
    ! grep -qoa 'getCurrentOutputStyleName=' "$1" 2>/dev/null && \
    ! grep -qoa 'function getCurrentOutputStyleName' "$1" 2>/dev/null
}

INSTALLED="$(readlink -f ~/.local/bin/claude 2>/dev/null)"

if has_bug "$INSTALLED"; then
    PATCHED="${INSTALLED}-patched"
    if [[ ! -f "$PATCHED" ]]; then
        cp "$INSTALLED" "$PATCHED"
        python3 -c "
import sys
path,n,r=sys.argv[1],sys.argv[2].encode(),sys.argv[3].encode()
d=bytearray(open(path,'rb').read()); pos=d.find(n)
if pos!=-1: d[pos:pos+len(n)]=r; open(path,'wb').write(d)
print(f'[wrapper] patched bug #71980 at offset {pos}')
" "$PATCHED" "$NEEDLE" "$REPLACEMENT" >&2
        chmod +x "$PATCHED"
    fi
    exec "$PATCHED" "$@"
else
    exec "$INSTALLED" "$@"   # no bug (old version or upstream fix) — pass-through
fi

Detection logic:

| Case | call present | definition present | action |
|------|----|---|---|
| ≤ 2.1.190 (old) | ✗ | ✗ | exec direct |
| 2.1.193–2.1.197 (buggy) | ✓ | ✗ | patch |
| Future fixed version | ✓ | ✓ | exec direct — wrapper is a no-op |

The wrapper patches once per new binary version (result cached as <version>-patched). When Anthropic ships a fix that includes the definition, has_bug returns false and the wrapper transparently falls through — no manual cleanup needed.

Tested on Linux x86_64, kernel 7.1.1-tigerlake, Claude Code 2.1.197.