The box an agent runs in — Rohan Adwankar

One awesome product evolution is that agents (Claude Code, Instinct, Poke, etc) are moving off our local computers so that we can use them on our phones. Ultimately this is great for the customer because that means the agent companies provide us with VMs for them to run on! Here's some notes on how the major platforms work based on looking around on ws-term.

Claude Code on Your Phone

Claude Code's box is its own Firecracker microVM, a KVM guest with its own kernel, booted straight into an init written in Rust:

$ cat /proc/cmdline
... rdinit=/process_api ... --listen-vsock-port 2024
$ uname -r
6.18.5-fc-v20                 # -fc- = Firecracker; a custom-built guest kernel
$ ps -o comm -p 1
process_api                   # PID 1 is not systemd; it's a Rust/Tokio binary

process_api is PID 1 and the host's control agent living inside your VM: it mounts the disks, then listens on vsock port 2024 so the host can drive the session from outside. That's the platform's defining trait: the operator lives inside your tenant space, and a lot of engineering goes into sealing it off (PID 1 is non-dumpable, /proc/1/mem is denied even with CAP_SYS_PTRACE, your shell is missing CAP_SYS_RESOURCE).

The disks split cleanly into yours (writable, persistent) and theirs (read-only, shared):

$ lsblk -o NAME,SIZE,RO,MOUNTPOINT
vda   256G  0  /                    # yours: writable, survives reclaim
vdc   341M  1  /opt/claude-code     # theirs: the 324 MB `claude` harness (Bun)
vdd  45.6M  1  /opt/env-runner      # theirs: the task launcher
vde/vdf ... 1  /mnt/skills/...      # theirs: skills

The harness is the thing running your tool calls and is a 324 MB compiled Bun binary on a read-only disk. The model runs elsewhere; inference goes out as Server-Sent Events over HTTPS/2 (not a WebSocket) to /v1/messages, through an egress gateway that is 443-only and MITM'd (CN = Egress Gateway ... (production)), with api.anthropic.com pinned in /etc/hosts. There is no inbound at all (192.0.2.2, an RFC-5737 test address). Auth is a host-minted OAuth token, cached root-only on disk and rotated per boot.

Lifecycle is host-driven and measured from the inside: ~430 ms to init, ~6.4 s to the harness process. Spin-up is triggered by an inbound message (the host wakes the VM over vsock and runs --session-mode resume); spin-down is idle reclaim decided by the host. When it's reclaimed, the processes die but vda detaches intact and reattaches on the next cold boot, which is why the conversation feels continuous even though the compute was destroyed.

flowchart TB
  user(["your keystrokes"]) -->|http post| ingress["session-ingress"]
  ingress --> pa
  hostctl(["host control plane"]) -->|vsock port 2024| pa
  subgraph vm["Firecracker microVM"]
    pa["process_api, pid 1, Rust"] --> harness["claude, 324 MB Bun harness"]
    vda[("vda (rw), yours, persists")] --- harness
    ro[("vdc/vdd/vde/vdf (ro), theirs")] --- harness
  end
  harness -->|inference over SSE| gw["egress gateway, 443, mitm, api.anthropic.com"]

Instinct

Instinct is a new startup which launched recently and it does some very nice things on the memory side which gives that feel of it being a real assistant rather than a chatbot.

$ hostname
e2b.local
$ cat /.e2b
n038afjvewg7jnc9pwdz

e2b.local means Instinct doesn't operate its own VM fleet; it rents E2B sandboxes ("sandbox-as-a-service"), a throwaway Ubuntu box you hand an agent so it has a computer:

Ubuntu 22.04.5, 2 vCPU, 1.9 GB RAM, 29 GB disk, up ~30 min, user sandbox (uid 1001)

And let's look under the hood...

$ systemd-detect-virt                  →  kvm
$ cat /proc/cmdline
  pci=off  virtio_mmio.device=4K@...  i8042.noaux i8042.nokbd  reboot=k  panic=1
  clocksource=kvm-clock  root=/dev/vda  ip=169.254.0.21::...:eth0:off:tap0
$ cat /sys/class/dmi/id/product_name   →  (empty)      # no SMBIOS at all
$ ps -o comm -p 1                      →  systemd       # init=/sbin/init, not a custom PID 1

Firecracker again!

pci=off + virtio-over-MMIO + empty DMI + tap0 networking is the Firecracker signature: no PCI bus, no SMBIOS, minimal devices. So both apps sit on the same microVM; the difference is who runs the fleet and what boots inside it. Where Claude Code boots a stripped custom init (process_api as PID 1), E2B boots a full Ubuntu with systemd and a whole XFCE desktop:

$ systemd-analyze
Startup finished in 265ms (kernel) + 992ms (userspace) = 1.258s
graphical.target reached after 977ms

~1.26 s to cold-boot all the way to a graphical desktop. The operator-in-guest exists here too, but it's just E2B's envd running as an ordinary systemd service, not a sealed PID 1. E2B sandboxes are configurable too (you pick the vCPU, RAM, disk, and idle timeout, and whether the box can be paused and resumed from a memory snapshot instead of cold-booted); Instinct runs a modest 2 vCPU / 1.9 GB desktop template.

So if the box is disposable, where does the agent's memory live? In a directory called /memory, and this is the platform's defining idea:

$ cat /memory/README.md
Persistent memory for [[rohan-adwankar]]
$ ls /memory
entities/  comms/  timeline/  workstreams/  knowledge/
$ git -C /memory log --format='%an <%ae>' -1
Instinct Agent <agent@instinct.com>

The agent's memory is a git repo of Markdown files with [[wiki-links]], navigated by grep. The timeline/ coarsens over time (raw → hourly → daily → weekly, like human memory), and the agent is literally the git author: it doesn't call a memory API, it writes Markdown and commits it as itself.

The durable layer is that repo, pushed to S3, keyed by a per-user id, and stored not as files but as a single git bundle, which is a great little gotcha:

$ git -C /memory remote -v
origin  s3://instinct-prod-agent-memory/filesystem-memory/user-01M1VW7...
$ aws s3 ls s3://.../user-01M1VW7.../ --recursive
  HEAD
  refs/heads/main/<sha>.bundle     # the ENTIRE vault, packed; `ls` after sync looks empty

Auth is short-lived STS credentials, not long-lived keys, so a leaked sandbox self-heals when the token lapses:

$ cat /etc/instinct-aws-creds
export AWS_ACCESS_KEY_ID='ASIA…'     # ASIA prefix + session token = temporary STS
...                                   # (values redacted, live secrets)
# role: instinct-sandbox-observations-role

flowchart TB
  subgraph box["E2B sandbox (rented, disposable)"]
    agent["Instinct Agent (agent@instinct.com)"] -->|writes and commits| mem["/memory, a Markdown vault git repo"]
    creds["/etc/instinct-aws-creds, short-lived STS"]
  end
  mem -->|git push| store
  creds -->|authorizes git push| store
  subgraph store["S3 (durable, per-user)"]
    vault[("instinct-prod-agent-memory, the vault")]
    obs[("instinct-prod-observations, raw firehose")]
  end

Durable thing = a git repo in S3. The machine is throwaway.

Using a git repo for this is quite nice; the default structure seems to be like this:

  ~/instinct-vault/..         │󰫎  24 󰲡 Vault
    .git                    │   23
    comms                   │   22 Persistent memory for 󱗖 rohan-adwankar. Markdown + wiki-links, navigated by grep. Start here, then jump
      chat                  │   21
         rohan-adwankar--inst│   20 Who Rohan is, what he is working on, and what is connected live in entities/, workstreams/, and knowled
    entities                │   19
      people                │󰫎  18  󰲣 Layout
         rohan-adwankar.md   │   17
      projects              │   15 README.md
         ws-term.md          │   14 timeline/     chronological record, coarsening upward: raw/ → hourly/ → daily/ → weekly/ → monthly/
    knowledge               │   13 entities/     people/ projects/ — the nouns of Rohan's world, one file each
      decisions             │   12 comms/        chat/ email/ meetings/ — one file per thread, named <who>--<topic>--<date>.md
         x-account-signup-dec│   11 workstreams/  active/ completed/ someday/ — units of work; status: frontmatter matches the subdirectory
      preferences           │   10 knowledge/    facts/ procedures/ preferences/ decisions/
        instinct            │    8
           autonomy.md       │    7 knowledge/preferences/instinct/ holds how Rohan wants the assistant itself to behave — autonomy, drafti
           iteration-style.md│    6
    timeline                │󰫎   5  󰲣 Conventions
      daily                 │    4
         2026-09-06.md       │    3 ● Every file has frontmatter with id, type, and aliases. [[id]] resolves to id.md or id/_index.md.
    workstreams             │    2 ● Entity and knowledge files are updated in place and read as current state, never as a log. History li
      active                │    1 ● Files that outgrow one page are promoted to a directory with an _index.md carrying the original id.
         dragon-game-asset.md│  25  - Timeline and comms hold events and conversations; entities hold durable properties only.
         startup-idea-search.│~
    󰂺 README.md               │~
~                             │~
~                             │~

:!tmux capture-pane -pS - | pbcopy

Now Claude Code's harness in the VM is open source and the same as normal but how about Instinct?

$ ps -eo args | grep -E 'agent-exec|tools'
agent-exec-server --port 8080                    # Go, runs the bash/code it's sent
tools __internal_daemon --socket /tmp/.tools/bridge.sock \
      --base-url https://api.instinct.com/-/api/graphql/tool-execute   # Rust
$ strings /usr/local/bin/tools /usr/local/bin/agent-exec-server \
    | grep -iE 'anthropic|openai|/v1/messages|x-api-key|claude|gpt|model'
                                                 # → nothing. no model listed

So it seems like there are no inference calls anywhere on the box. Claude Code seals the operator inside the guest; Instinct doesn't put the brain in the guest at all. The sandbox is a pure execution surface: agent-exec-server runs whatever bash the backend hands it, and every tool call (Gmail, the cloud browser, a payment) leaves as a GraphQL request to api.instinct.com, executed server-side. The --base-url is a runtime argument, not compiled in.

For the actual tool surface, rather than MCPs, Instinct seems to use a CLI for all tools:

sandbox@e2b:~/ws-term-v1$ tools --help | wc
     90    1466   10891
sandbox@e2b:~/ws-term-v1$ tools --help
Tools CLI

You are a task agent. Your parent (the main agent) spawned you for a focused job. When the job is done, report back to your parent and hold. Your parent owns task-agent cleanup.

Your direct-execute traits:
  - work - integrations, files, web page fetching
....

Run `tools --help` for the current surface.

USAGE
  tools <command-path> [options]
  tools help [<path>...]

....

Built-ins (no help read needed): help, async wait, async list.

EXECUTABLE (you can call these directly)
  agent_message        namespace (1 action)   Send messages to other agents.
  browser_guidance     namespace (3 actions)  Search per-config website guidance and this user's past outcomes before browser navigation, and record how a config performed after an attempt. Missing guidance is normal and means unknown, not supported or blocked.
  cloud_browser        namespace (27 actions) Drive a cloud-hosted Chrome lease with the user's saved logins. Use for agent-driven web tasks (order food, book rides, compare prices, fetch receipts) that need real authenticated capability on real sites. A task agent acquires its own `lease_id` with `tools cloud_browser_scheduler acquire` and drives it here.

....

DELEGATED (only callable by the other role)
  account              namespace (2 actions) Read the user's Instinct account profile.
  feedback             namespace (3 actions) Submit product feedback and respond to team follow-ups.
  generate_referral_link action                Ask the main agent to get the member's reusable referral link and current lifetime allowance.
  revoke_referral_link action                Ask the main agent to revoke the member's reusable referral link.
  speak                action                Generate a WAV speech file from a transcript, optional director's notes, and a voice.

UNAVAILABLE (does not apply to this role)
  steer_voice_agent    action     Send an answer or context into the user's active live voice session.

The tool surface is the tell that this box isn't a coding sandbox at all. tools --help lists ~50 namespaces (Gmail, Notion, Slack, Stripe payments, a credential vault), but the one that reveals the design is the cloud browser:

$ tools --help | grep -iE 'cloud_browser|vault'
cloud_browser            (27)  Drive a cloud-hosted Chrome lease with the user's saved logins.
cloud_browser_scheduler  (4)   acquire, list, release, extend leases
vault                    (7)   Manage, fill, and import the user's stored credentials

When Instinct orders food or books a flight "as you," it does not open a browser on this sandbox. It leases one from a separate pool of cloud browsers, each carrying your saved profile (cookies and logins) and drives it through the same api.instinct.com bridge:

tools cloud_browser_scheduler acquire      # → lease_id, on a browser "config" (a profile)
tools cloud_browser <action>               # click / type / read / screenshot that Chrome

You can read the whole model off how leases behave: each profile has exactly one write lease (the only session allowed to save new logins), up to five run at once, and releasing a lease "saves its cookies first, so the next lease loads them." That persistence is the point: your browser identity is a third durable thing, sitting server-side next to the S3 vault and the observations index, kept so a disposable box can borrow it for one task and hand it back. Two details let it sign in without a secret ever touching the box:

• Scout before navigating. tools browser_guidance search returns curated per-site notes plus your own past outcomes per profile (config-a: success, config-b: blocked), a risk prior, not a verdict.
• Secrets go through the Vault, never chat. tools vault fill types a stored credential straight into the page; when the vault lacks one, tools vault request mints a link you fill (app.instinct.com/vault/fill?t=…). One-time codes it reads itself from your connected Gmail or Outlook.

flowchart TB
  ta["task agent, off-box"] -->|acquire lease| sched["cloud_browser_scheduler"]
  sched --> cb
  ta -->|click, type, read| cb["cloud browser with your saved profile"]
  vault[("Vault, your secrets, server-side")] -->|fill| cb
  cb -->|"logged in as you"| sites(["Amazon, Uber, airlines, and more"])
  box["disposable E2B box"] -->|"issues tools calls, holds no cookies"| cb

Summary

This was pretty fun to take a peek, and I'll keep recording my notes as new products come around!