How to Sync Context Across Separate Claude Code Sub-Agent Sessions (Step-by-Step Guide)

Running multiple Claude Code sub-agent sessions in parallel (for example, a dedicated debugger and a code-reviewer) is powerful for focus and productivity. But there’s one problem: sessions don’t share context by default.

This guide shows you how to sync context across separate sub-agent sessions. You’ll learn:

• Four different strategies for context sharing

• When to use repo files vs. databases vs. MCP integrations

• A step-by-step, automated SQLite context sync tool you can install in minutes

By the end, you’ll have a repeatable workflow for sharing notes and state across multiple Claude Code sessions—no more manual copy/paste.

---

Table of Contents

1. Why context sync matters

2. 4 proven strategies for context sharing

3. Step-by-step: Automating context sync with SQLite

4. Example workflow with parallel sub-agents

5. Troubleshooting & best practices

6. Next steps: Hooks for automatic syncing

---

Why context sync matters

When you run sub-agents like a debugger, code-reviewer, or doc-writer in separate Claude Code sessions, each one has its own context window. Without a sync strategy, you risk:

• Losing critical debugging notes

• Duplicating work across sessions

• Forgetting what other agents have already solved

Context syncing ensures that your multi-agent workflow stays coordinated and efficient.

---

4 Proven Strategies for Context Sharing

1. Markdown Notes in Repo

• Store shared notes in .claude/context/*.md

• Simple, human-readable, and version-controlled

• ✅ Easy to set up, but can grow noisy

2. SQLite Scratchpad (recommended)

• Structured, queryable context DB

• Easy to automate with a ctx CLI tool

• ✅ Scales better than raw markdown

3. MCP-Backed Stores (Redis, external DB)

• Centralized context accessible via Model Context Protocol (MCP) integrations

• Best for teams or multi-machine setups

• ⚠️ Requires extra setup and permissions

4. Regenerate on Demand

• Each sub-agent recomputes its needed context from git diffs, logs, or tests

• ✅ Zero coupling

• ⚠️ Doesn’t share rationales or decisions

---

Step-by-Step: Automating Context Sync with SQLite

This section walks you through building a drop-in context scratchpad with SQLite that any Claude Code sub-agent session can read/write.

0) Scaffold

mkdir -p tools .claude/context
python -m venv .venv && source .venv/bin/activate
pip install --upgrade pip
pip install tabulate

1) Add the CLI (tools/ctx.py)

#!/usr/bin/env python3
import argparse, sqlite3, os, time
from tabulate import tabulate

DB_PATH = os.environ.get("CTX_DB", ".claude/context/context.db")

DDL = """
CREATE TABLE IF NOT EXISTS entries (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  ts INTEGER NOT NULL,
  agent TEXT NOT NULL,
  session TEXT,
  topic TEXT,
  summary TEXT,
  refs TEXT
);
"""

def connect():
    os.makedirs(os.path.dirname(DB_PATH), exist_ok=True)
    conn = sqlite3.connect(DB_PATH)
    conn.executescript(DDL)
    return conn

def cmd_add(args):
    conn = connect()
    with conn:
        conn.execute(
            "INSERT INTO entries(ts, agent, session, topic, summary, refs) VALUES(?,?,?,?,?,?)",
            (int(time.time()), args.agent, args.session, args.topic, args.summary, args.refs)
        )
    print("ok: added")

def cmd_read(args):
    conn = connect()
    q = "SELECT ts, agent, session, topic, summary, refs FROM entries ORDER BY ts DESC LIMIT ?"
    rows = conn.execute(q, (args.limit,)).fetchall()
    out = []
    for ts,agent,session,topic,summary,refs in rows:
        out.append([time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(ts)), agent, session or "", topic or "", (summary or "")[:240], refs or ""])
    print(tabulate(out, headers=["time","agent","session","topic","summary","refs"], tablefmt="github"))

def main():
    ap = argparse.ArgumentParser()
    sub = ap.add_subparsers(dest="cmd", required=True)

    ap_add = sub.add_parser("add")
    ap_add.add_argument("--agent", required=True)
    ap_add.add_argument("--session", default="")
    ap_add.add_argument("--topic", default="")
    ap_add.add_argument("--summary", required=True)
    ap_add.add_argument("--refs", default="")
    ap_add.set_defaults(func=cmd_add)

    ap_read = sub.add_parser("read")
    ap_read.add_argument("--limit", type=int, default=50)
    ap_read.set_defaults(func=cmd_read)

    args = ap.parse_args()
    args.func(args)

if __name__ == "__main__":
    main()

Make it executable:

chmod +x tools/ctx.py

2) Use it in Sub-Agent Prompts

Example debugger.md:

---
name: debugger
description: Debugging specialist for errors and test failures. Auto-syncs context.
tools: Read, Write, Grep, Glob, Bash
---

## Context Sync (before work)
- Run: `Bash -> python tools/ctx.py read --limit 20`
- Integrate relevant issues from other agents.

## Task Procedure
1) Capture error/stack trace
2) Localize failure region
3) Apply smallest safe fix
4) Verify with tests

## Context Sync (after work)
- Summarize root cause, fix, verification
- Run: `Bash -> python tools/ctx.py add --agent debugger --session "<label>" --topic "<topic>" --summary "<summary>" --refs "<files>"`

3) Example Session Usage

• Start code-reviewer session: log issues with ctx add

• Start debugger session: load reviewer notes with ctx read, then append fix summary

• Start doc-writer session: load both, generate release notes

Now, all three sessions share a durable context database.

---

Example Workflow with Parallel Sub-Agents

Session A (code-reviewer)

• Review commit

• Log summary with ctx add

Session B (debugger)

• Load reviewer context with ctx read

• Apply fix

• Append summary with ctx add

Session C (doc-writer)

• Load reviewer + debugger context

• Update documentation

• Save context

This pattern creates a multi-agent workflow with shared state across sessions.

---

Troubleshooting & Best Practices

• Nothing appears in read? Check your DB path or limit flag.

• Label consistently: Use session IDs like CR-12, DBG-45.

• Avoid logging secrets: Keep .claude/context/ in .gitignore.

• Summarize, don’t dump: Add concise notes, not full logs.

---

Next Steps: Hooks for Automatic Syncing

Right now, agents politely run ctx read at the start and ctx add at the end. In the next article, we’ll explore Claude Code Hooks to enforce this automatically—for example:

• Run ctx read before every task (PreTask hook)

• Run ctx add after every task (PostTask hook)

This ensures every sub-agent session consistently loads and writes context—even if you forget.

---

Internal Resource

👉 If you’re new to sub-agents, start with our Beginner’s Guide to Claude Code Sub-Agents.