Devin CLI

  • ID: devin
  • Store: <data>/devin/cli/sessions.db — ~/.local/share/devin/cli/sessions.db on Linux and macOS (verified on both; XDG_DATA_HOME honoured); %LOCALAPPDATA%\devin\cli\sessions.db on Windows is the platform convention the binary's own strings name — unverified there — with cli_sessions.db beside it holding the pre-rename copy
  • Summaries: <data>/devin/summaries/<session_id>.md
  • Read override: DEJA_DEVIN_DB replaces the store path
  • Format: SQLite, two tables per conversation — sessions for the row, message_nodes for the turns — plus prompt_history for the inline shell commands run between turns
  • Needs: sqlite3

Devin CLI (Cognition's local devin binary) keeps one store for every session.

A session is a row of sessions plus its nodes in message_nodes — but the

table in order is not the conversation. The agent rebuilds its context chain

whenever the system prefix changes, so the table keeps every copy, several of

them sharing their message_ids, and sessions.main_chain_id names the head

of the live one. Reading backwards over parent_node_id from that head and

keeping one copy of each message_id gives the conversation the model saw;

chains the main one cannot reach are run_subagent runs sharing the same

table, indexed as subagent sessions of the parent.

Every timestamp is unix seconds. A node's chat_message JSON is

`{"role":"system|user|assistant|tool","content":…,"tool_calls":[{"id","name",

"arguments"}]}; the node's own metadata` column marks rebuilt scaffolding

with is_system_prefix, and a tool row carries its exit code at

chat_message.metadata.extensions."chisel/terminal_output".exit.exit_code.

A system row without the flag is context something injected — a hook's

additionalContext lands verbatim — and is kept as tool output.

prompt_history.is_shell = 1 rows are the commands the user ran between turns.

devin --resume <id> takes the sessions row's id and finds the session in the

one global store; the recorded working_directory is where it ran.

deja install devin writes ~/.config/devin/mcp_config.json (user scope;

project scope is .devin/mcp_config.json) and the shared

~/.agents/skills/deja-history/SKILL.md, which Devin's own docs list among

its skill directories. deja install devin-auto additionally writes Claude-

shaped hooks into the "hooks" key of ~/.config/devin/config.json:

SessionStart and PostCompaction run hook-context, UserPromptSubmit runs

hook-prompt, PostToolUse runs hook-tool (matcher `exec|edit|write|

apply_patch|notebook_edit) and hook-tool-after` (matcher

^exec$), and SessionEnd runs hook-session-end. Devin's hook replies must

name the event that fired, which is why the hooks emit hook_event_name from

the payload rather than their compiled-in names; on Claude's events nothing

changes.

devin-plugin/ in this repo ships the same wiring as a Devin plugin —

.devin-plugin/plugin.json with the MCP server, hooks.json, and the skill —

installed with devin plugins install vshulcz/deja-vu#devin-plugin. Devin's

cloud sessions are reported to fire plugin hooks on a smaller event set —

SessionStart and SessionEnd among the ones not delivered, though the plugin

docs are a closed beta and the list is not public — so on those the opening

digest and the end-of-session marker may be CLI-only; `deja install

devin-auto` stays the recommended path. Where both are present the plugin's

hooks see the wiring in ~/.config/devin/config.json and stand down.

Last verified: 2026-10-07 (Devin CLI 3000.11.3)

Known quirks and drift

  • additionalContext under PreToolUse is silently dropped. Devin accepts

the reply and never delivers the context, so hook-tool rides on

PostToolUse — late for the action that fired it, in time for everything the

agent does next on that file. Replies must also echo the firing event's name

in hookEventName: a PostToolUse reply that says "PreToolUse" is dropped

the same way (both verified on 3000.11.3).

  • Hook payloads carry no cwd. The launcher sets DEVIN_PROJECT_DIR for

the hook's own process, which hookCWD reads after CLAUDE_PROJECT_DIR.

  • A rebuilt chain is duplication, not replay. Nodes after a rebuild repeat

earlier messages under the same message_id; dedupe by message_id, not

position, or a compacted session reads its user turns twice.

  • subagent_heads exists but is empty on the observed builds. When a

build populates it, its declared agent_id names the sub-session; when it

stays empty, side chains are found structurally — the NULL-parent roots

the main chain never reaches, which is also how chains a rewind orphaned

still surface.

  • PostToolUse is also the failure event. Devin has no PostToolUseFailure:

a nonzero exit arrives as an ordinary PostToolUse with success: false, so

one hook-tool-after wiring covers both paths.

  • Hidden sessions are marked, not deleted: sessions.hidden = 1, and the

parser leaves them out — indexing one would resurrect a session its owner

removed from view.

deja reads this format and forty others, and turns what it finds into memory your agents can search. See the harness matrix for what is wired where, or install it and search your own history.

Found this useful? Star deja-vu on GitHub.