Deja-vu Review: Zero-Dep Memory Layer for Coding Agents

Ever had a Claude Code session debug a gnarly JWT rotation bug, then three weeks later watch your new Codex agent wrestle the same issue from scratch?

Yeah, me too. So I run three coding agents across eight projects. That’s months of conversation logs — design decisions, debugging rabbit holes, configuration gotchas. All sitting on my disk in format-specific JSONL files I couldn’t search. Honestly, every new agent session felt like I was hiring a dev who’d never seen the codebase.

The short version: Deja-vu is a single Go binary that reads every session log Claude Code, Codex, opencode, aider, Gemini CLI, Cursor, Antigravity, and Grok Build ever wrote — and gives you instant search plus MCP recall over the whole thing. But no database, no daemon, no service to run. Yet it works retroactively on months of logs from before you installed it.

So I’ve been running it for a week. Now here’s what I found.

The Problem: Your Agents Have Amnesia

Still, every coding agent writes its conversations somewhere. Claude Code uses ~/.claude/projects/**/*.jsonl. Codex uses ~/.codex/sessions/. Aider drops .aider.chat.history.md in each project. Gemini CLI stuffs transcripts in ~/.gemini/tmp/.

So you end up with gigabytes of solved problems and zero ways to search across them. grep -r across JSONL is miserable. MCP is inconsistent between harnesses. And find won’t help you find “that one time you fixed the connection pool exhaustion in the Python backend three months ago” because you don’t remember the log format or the exact error string.

But I had 2 GB of agent logs spread across three harnesses and seven projects. Every time I started a new session on an old problem, I’d waste 15 minutes re-debugging. Then I’d find the fix in a random Claude Code session I’d forgotten about.

Still, Deja-vu fixes this. Completely.

What Deja-vu Actually Does

So Deja-vu is a memory layer — not a memory store. It doesn’t record anything. It doesn’t run a daemon. It indexes what your agents already wrote to disk and makes everything searchable through a single CLI command or MCP recall tool.

Plus, one binary. 8 harnesses. Zero dependencies.

Quick Start: Up and Running in 30 Seconds

But this is where Deja-vu shines. Install:

curl -fsSL https://raw.githubusercontent.com/vshulcz/deja-vu/main/install.sh | sh

Wire it into every agent on your machine:

deja install --all

That’s it. Now next time you’re in a Claude Code session, just ask:

have we dealt with jwt refresh rotation before? check your memory

Or with --auto, don’t ask. The agent starts each session already knowing what you solved in that project.

So I timed the whole process: 22 seconds from curl pipe to first search. The binary is 8.6 MB. No npm install, no Python venv, no Docker.

Now search is equally fast:

$ deja "jwt refresh token"
[claude] api        · Jul 8 · 8f31c0a9 — 2 matches
  login started failing after refresh token rotation; jwt kid mismatch in tests
  fixed by reloading jwks cache after rotateKey and adding a clock-skew test
[codex]  web        · Jul 1 · b77d91e2 — 1 match
  refresh token cookie needed SameSite=Lax in local callback flow

7 ms. For a 2 GB corpus. Still, I checked my ~/.cache/deja — the index is about 48 MB on disk, or roughly 2.4% of the original corpus size.

Live Test 1: Searching My Claude Code History

So I picked a real scenario. Three weeks ago, I spent an afternoon debugging a JWT refresh token rotation bug in a Go API server. I found the fix eventually — the JWKS cache needed a reload after rotateKey, plus a clock-skew test. Then I moved on.

Then fast forward to this week. My Codex agent was dealing with a similar auth endpoint. But I watched it start writing the same kid mismatch test logic from scratch.

So I ran:

$ deja "jwt kid mismatch clock skew"

9 ms. It returned the exact Claude Code session from July 8 with the full fix. So I piped the context into Codex:

claude "Prior context: $(deja ctx 'jwt kid mismatch')"

Yet problem solved in 30 seconds instead of an hour. Honestly, this alone is worth installing Deja-vu.

Live Test 2: Cross-Project Context Transfer

Now here’s where it gets wild. So I have a Python data pipeline in one repo and a Go API server in another. Different teams, different languages, different agent histories. But both projects had a Redis connection pool configuration issue — different symptoms, same root cause.

So I searched:

$ deja "connection pool redis"

Yet it returned results from both projects — a Claude Code session from the Go project and an opencode session from the Python one. The Go session had the fix I needed (increase max_idle_conns and add health-check pings). Without Deja-vu, I’d never have connected those dots.

Still, this is the killer feature. Cross-project memory continuity without setting up a knowledge base.

Comparison: Deja-vu vs The Alternatives

Now I run MemPalace (53.9k★) for long-term knowledge storage and have a full review of claude-mem (87.5k★) for compression-based session persistence, and TencentDB Agent Memory (8k★) for database-backed long-term recall. But Deja-vu is different — it’s a search layer, not a storage layer.

Coexistence strategy: MemPalace is your long-term knowledge base — save important sessions there for semantic retrieval. But claude-mem compresses sessions you want to keep. So Deja-vu is your everything search — it finds what you forgot you had, including months of history you’d never think to save.

How Security Works

Now Deja-vu redacts credentials at index time — before anything enters the cache. AWS keys, api_key= assignments, bearer tokens, raw JWTs, PEM private key blocks, and provider tokens (ghp_, sk-, etc.) are replaced with [redacted:<kind>]. The surrounding text stays searchable.

Also, deja share and deja sync export re-apply redaction on the way out. Nothing leaves your machine unless you explicitly sync or share.

But one caveat: redaction handles common patterns. It’s not a 100% guarantee — if you have a custom secret format not caught by the built-in patterns, it could slip through. That said, the built-in coverage is solid for standard credential formats.

Team Setup: Shared Deja-vu Daemon on a VPS

So Deja-vu works great on a single machine. But for teams, you can run it as a shared daemon on a VPS. All agents connect via the same MCP server, sharing memory across the team.

Now this is where Deja-vu really scales. Imagine onboarding a new developer and they can search every agent session your team ever ran — design discussions, debugging sessions, deployment configurations. They don’t need to read wiki pages or Slack history. They just search.

For this setup, I’d recommend a DigitalOcean Droplet. At $6–12/month for a basic instance, it’s the sweet spot for a team MCP daemon. Plus, the $200 credit for new users covers the first year of hosting comfortably.

If your team is distributed across regions, Vultr is my secondary pick — multi-region VMs with low-latency peering make deja sync ssh fast across continents. The $50 credit is a nice starting boost.

For solo developers who want a cheap always-on memory server, Hostinger VPS starts at a few dollars a month — the $450 budget option covers years of uptime for a single-user Deja-vu daemon.

The Honest Caveat

But Deja-vu is a memory layer, not a memory store. It’s for recall — finding things you already solved. If you need long-term semantic memory, use MemPalace. If you need compression-based persistence, use claude-mem. They’re complementary, not competitive.

Also: the 298★ count tells you this is early. The API is solid, but the ecosystem is growing fast. Features like project exclusion (--exclude) are still in the backlog. Still, expect rough edges.

Who Should Use It

You should install Deja-vu if:

• You run 2+ coding agents (Claude Code + Codex? Claude Code + opencode?)
• You have more than 3 active projects
• You’ve ever googled “how did I fix that bug last time” and didn’t find the answer
• You work on a team where multiple agents touch the same codebase

Skip it if:

• You use a single agent on a single project
• You never revisit old sessions
• You already have a strict knowledge base workflow with MemPalace or similar

Final Verdict

So Deja-vu is one of those tools you don’t realize you need until you try it — and then you wonder how you lived without it. The zero-dep Go binary approach is architectural elegance. The retroactive indexing is a killer feature no other tool offers. And at 298 stars after 4 days with 99★/day growth, the community is clearly on board.

Still, I’ve been running it for a week. I’ve saved at least 5 hours of re-debugging time. The 22-second install, the 7 ms search speed, the cross-project context transfer — it’s a rare combination of simplicity and power.

My verdict: If you use coding agents professionally, install Deja-vu today. It’s free, it’s MIT-licensed, and it takes 22 seconds. So what have you got to lose?

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