claude-session-recover

A developer created a Python script called `claude-session-recover` to fix Claude Code sessions stuck in an unrecoverable loop caused by a server-side API validation error. The tool removes `thinking` and `redacted_thinking` blocks from session transcripts on disk, eliminating the signature mismatch that prevents the stateless API from accepting further requests. The fix preserves all text, tool calls, and tool results while repairing the parentUuid chain to maintain rewind functionality, though the developer notes this is a client-side stopgap for a server-side issue that began appearing around May 28, 2026.

| /usr/bin/env python3 | | | """Recover a Claude Code session stuck in a loop on this API 400 error: | | | " thinking or redacted thinking blocks in the latest assistant message | | | cannot be modified. These blocks must remain as they were in the original | | | response." | | | Thinking blocks carry a server-issued signature that the stateless API | | | re-validates on every request. When a transcript ends up with those blocks in a | | | context the signature no longer matches e.g. duplicated/merged turns after a | | | rewind or compaction , every resend is rejected and the session is wedged — no | | | prompt, /compact, or rewind gets you out. | | | This script fixes the transcript on disk. It's the persistent equivalent of | | | "turn thinking off": it removes every thinking / redacted thinking block, so | | | there are no signatures left to validate. You keep ALL text, tool calls, and | | | tool results — you only lose the model's prior private reasoning, so the next | | | turn reasons fresh. Empty assistant entries are dropped and the parentUuid chain | | | is repaired so /rewind still works. Every other line is passed through | | | byte-for-byte. Pure Python 3 stdlib — no pip installs. | | | NOTE: this is a client-side stopgap. The underlying cause appears to be | | | server-side a wave of these started 2026-05-28; see claude-code issue 10199 . | | | It recovers a stuck session but does not prevent recurrence. | | | ---------------------------------------------------------------------------- | | | USAGE | | | ---------------------------------------------------------------------------- | | | 1. Find your session file. It lives at | | | ~/.claude/projects/<encoded-cwd /<session-id .jsonl | | | The session id is shown in the Claude Code footer, or just grab the newest: | | | ls -t ~/.claude/projects/ / .jsonl | head | | | 2. QUIT Claude Code for that session first. If it stays open, it will | | | overwrite this fix with its in-memory copy when it exits. | | | 3. Run one of: | | | python3 claude-session-recover SESSION.jsonl --check report only, writes nothing | | | python3 claude-session-recover SESSION.jsonl writes SESSION.jsonl.fixed to inspect | | | python3 claude-session-recover SESSION.jsonl --in-place rewrites it auto-backup to .bak-<ts | | | 4. Resume: cd <the session's project dir && claude --resume <session-id | | | To undo an --in-place run, copy the .bak-<timestamp file back over the original. | | | """ | | | import json | | | import os | | | import sys | | | import time | | | THINK = {"thinking", "redacted thinking"} | | | def process lines : | | | Parse each raw line, preserving the original text for pass-through. | | | parsed = | | | for raw in lines: | | | s = raw.strip | | | if not s: | | | parsed.append raw, None | | | continue | | | try: | | | parsed.append raw, json.loads s | | | except json.JSONDecodeError: | | | parsed.append raw, None | | | dropped uuid to parent = {} | | | stripped blocks = 0 | | | dropped entries = 0 | | | staged = keep, raw, obj, modified | | | for raw, obj in parsed: | | | if obj is None or obj.get "type" = "assistant": | | | staged.append True, raw, obj, False | | | continue | | | msg = obj.get "message" or {} | | | content = msg.get "content" | | | if not isinstance content, list : | | | staged.append True, raw, obj, False | | | continue | | | kept = b for b in content | | | if not isinstance b, dict and b.get "type" in THINK | | | removed = len content - len kept | | | if removed == 0: | | | staged.append True, raw, obj, False | | | continue | | | stripped blocks += removed | | | if not kept: | | | dropped uuid to parent obj.get "uuid" = obj.get "parentUuid" | | | dropped entries += 1 | | | staged.append False, raw, obj, True | | | else: | | | msg "content" = kept | | | staged.append True, raw, obj, True | | | def resolve p : | | | seen = set | | | while p in dropped uuid to parent and p not in seen: | | | seen.add p | | | p = dropped uuid to parent p | | | return p | | | out = | | | relinked = 0 | | | for keep, raw, obj, modified in staged: | | | if not keep: | | | continue | | | if obj is not None and obj.get "parentUuid" in dropped uuid to parent: | | | obj "parentUuid" = resolve obj.get "parentUuid" | | | relinked += 1 | | | modified = True | | | if modified: | | | out.append json.dumps obj, ensure ascii=False + "\n" | | | else: | | | out.append raw if raw.endswith "\n" else raw + "\n" | | | return out, { | | | "stripped blocks": stripped blocks, | | | "dropped empty entries": dropped entries, | | | "relinked parents": relinked, | | | } | | | def main argv : | | | if len argv < 2: | | | print doc | | | return 2 | | | path = argv 1 | | | in place = "--in-place" in argv 2: | | | check = "--check" in argv 2: | | | with open path, "r", encoding="utf-8" as f: | | | lines = f.readlines | | | out, stats = process lines | | | print f"input lines : {len lines }" | | | print f"output lines: {len out }" | | | print f"thinking/redacted blocks stripped : {stats 'stripped blocks' }" | | | print f"empty assistant entries dropped : {stats 'dropped empty entries' }" | | | print f"parentUuid links repaired : {stats 'relinked parents' }" | | | if check: | | | print " --check no files written" | | | return 0 | | | if in place: | | | src mode = os.stat path .st mode & 0o777 | | | backup = f"{path}.bak-{int time.time }" | | | with open backup, "w", encoding="utf-8" as f: | | | f.writelines lines | | | os.chmod backup, src mode | | | with open path, "w", encoding="utf-8" as f: | | | f.writelines out | | | print f"backup written: {backup}" | | | print f"rewrote in place: {path}" | | | else: | | | dest = f"{path}.fixed" | | | with open dest, "w", encoding="utf-8" as f: | | | f.writelines out | | | print f"fixed copy written: {dest}" | | | return 0 | | | if name == " main ": | | | sys.exit main sys.argv |