specflo

Spec-driven software engineering for coding agents. specflo is a Python CLI
plus a set of skills and hooks that give an AI agent a disciplined
brainstorm -> spec -> plan -> execute loop, with every artifact (specs, plans,
decisions, tasks) written to plain markdown on disk instead of living in the
model's context window.

• State lives in files, not in the model's head. Phase state, validation
  gates, and one-task-at-a-time focus live in the CLI and on disk. That makes
  agentic development more reliable, and it makes real development practical
  with capable but smaller local models such as Qwen3.6 27B: the agent only
  has to reason about the next small, well-scoped, validated step, not hold an
  entire project in context.
• Multi-project by design. specflo tracks many projects in one repo with a
  single active project and switch-anytime, so a monorepo can carry several
  concurrent efforts without them stepping on each other. Each project keeps
  its own phase, artifacts, and resume checkpoint.
• Pluggable into any harness that can run a CLI and read markdown. Claude
  Code and pi are integrated out of the box (skills, session-start hook, a
  bundled pi extension); opencode and Hermes get the skills; anything else can
  drive the plain CLI.

specflo is built with itself: every feature since v0.1 has gone through its own
brainstorm -> spec -> plan -> execute pipeline. The CHANGELOG
is the development history. Pre-1.0, interfaces may still move; breaking
changes are called out explicitly in the changelog.

Quick start

Requires Python 3.12+. Install from PyPI:

uv tool install specflo    # or: pipx install specflo / pip install specflo

Then set up the repo you want to work in:

specflo init                # scaffold .specflo/ config + the projects dir
specflo skills install      # install the workflow skills into your agent harness(es)
specflo hook install        # Claude Code: session-resume wiring (recommended)
specflo extension install   # pi: same session-resume wiring, as a pi extension

The last two lines are per-harness alternatives - run the one that matches your
agent, or neither if it is some other harness.

That is the whole setup. Start your coding agent and say:

We use specflo here. Start a new specflo project for .

The specflo-brainstorm skill takes over - one question at a time, decisions recorded on
disk - and hands off through spec and plan to task-by-task execution. Every
step also works without an agent; see the
command reference.

Using specflo with your agent

The installed skills make your agent able to drive specflo; a note in the
project memory file (CLAUDE.md, AGENTS.md, ...) makes it routine. Paste
this near the top of that file:

## Development workflow

This repo uses specflo for feature development. Run `specflo guide` at the
start of a session to orient yourself; `specflo status` shows the active
project and phase. Features move through brainstorm -> spec -> plan -> execute
using the specflo skills, recording decisions, requirements, and tasks through
the specflo CLI rather than editing its artifacts by hand.

Prompts that map onto the workflow:

• "Start a new specflo project for X." - creates the project, opens the brainstorm.
• "continue" - after a fresh start or a context clear, resume from the checkpoint.
• "Where are we?" - the active project's phase and next step (specflo status).
• "Park this for now." / "Pick that back up." - shelve and resume a project.
• "Run it in auto mode." - explicit opt-in to an unattended run (see specflo auto).

specflo guide runs cold - before init, in any repo - and orients a fresh
agent in one shot: what specflo is, the pipeline, the full command surface, and
what to do next. When in doubt, tell your agent to run it.

The pipeline

Four phases, each gated by a validated artifact:

1. brainstorm - capture the idea; resolve open questions into recorded decisions (D-NN).
2. spec - synthesize testable requirements (REQ-NN), each traced to the decisions behind it.
3. plan - decompose into dependency-ordered tasks (T-NN), each with an acceptance criterion, a verify step, and the requirements it implements; optionally grouped into milestones (M-NN).
4. execute - work tasks one at a time; a completion gate confirms every task is done and that the final whole-branch review was recorded with a passing verdict before the project completes.

specflo advance validates the current phase's artifact before moving on, so a
hole in the spec stops the line early instead of surfacing mid-execution.

The end-of-execute review is an artifact too. specflo review start mints a
numbered review-N.md; specflo review done --verdict ... closes it with one of
ready-to-merge, changes-requested or waived. Completing the project
requires the latest round to have closed with a passing verdict, so a review that
happened in some cleared context is no longer something you have to remember.

Artifacts are plain markdown under docs/projects/<slug>/ (configurable):

$ specflo status
Project: Payment retries (payment-retries)
Dir:     docs/projects/payment-retries
Phase:   brainstorm
Next:    Brainstorm and research; capture decisions, then write the spec.
Resume:  specflo checkpoint

Clearing context is free at any point: checkpoint.md is rewritten after every
state change, and specflo checkpoint prints the resume prompt that puts a
fresh session back to work.

Command reference

Global option: run in another directory

• specflo -C DIR <command> / specflo --directory DIR <command> - run the command as if specflo had been started in DIR. Every command honors it, including init, hook reseed, auto, and extension install --scope project; root discovery is the usual walk up from DIR to the nearest .specflo/config.yaml. DIR must exist and be a directory, or the command exits 2 before anything runs. The option goes before the subcommand.
• SPECFLO_DIRECTORY=DIR - the environment variable has the same effect. Precedence is the flag, then the env var, then the current directory; a set-but-empty variable counts as unset.
• Relative path arguments given to the subcommand (review done --file report.md, init --projects-dir custom) resolve against DIR, not the caller's cwd - the same contract as git -C.
• The change lasts only for the command: the process cwd is restored when the command finishes.
• SPECFLO_DIRECTORY reaches everything that inherits the environment: the Claude Code SessionStart hook, the pi extension (its specflo calls and its statusline segment), and any subagent an orchestrating agent spawns. This is the intended effect for an agent driving a project in another tree. To make the redirect visible, specflo status prints a Root: <path> (via -C|SPECFLO_DIRECTORY) line (and root / directory_source keys in --json) when the directory was overridden, and the reseed payload from specflo hook reseed leads with one line naming the root when the env var is set. Without an override, all outputs are unchanged.

Setup and orientation

• specflo --version - print the installed version and exit.
• specflo guide [--json] - orientation in one shot: what specflo is, the pipeline, the full command surface, and what to do next here. Runs cold (works before specflo init), so a fresh agent can get up to speed in any repo.
• specflo init - scaffold .specflo/config.yaml + the projects dir (default docs/projects/).

Configuration

• specflo config get <key> - print one setting's resolved value, bare on stdout, so $(specflo config get autonomy) is the value itself. An unset key prints its shipped default.
• specflo config list [--json] - every setting with its resolved value, in registry order. A line ends with (default) when the file is silent about that key, or (invalid, using default) when the file's value is not one the key accepts. Keys specflo does not recognize are listed separately and left alone. --json reports each key's value and a source of set, default, or invalid.
• specflo config set <key> <value> [--force] - set one setting. The value is coerced to the key's type and validated before the write, so a rejected value leaves the file untouched and the error names what the key accepts. active_project is refused (use specflo switch), and projects_dir needs --force while projects live under the current path - changing it moves nothing, it only changes where specflo looks.
• specflo config unset <key> [--force] - drop one setting; it returns to the commented-out default line under its description, and reads as its shipped default again.

See The config file for the file itself.

Projects

• specflo new <name> - create a project and make it active.
• specflo list [--json] - list all projects, marking the active one and its phase.
• specflo switch <name> - make another project active (by slug or name).
• specflo status [--json] - show the active project, its phase, and what's next.
• specflo shelve [<name>] [--reason ...] - set a project aside: status shelved, phase untouched.
• specflo resume [<name>] - pick a shelved project back up at the phase where it was paused.

Phase artifacts

• specflo brainstorm start [--json] - create (or locate) the active project's brainstorm.md.
• specflo decision add --text ... [--rationale ...] [--supersedes D-NN] - append a decision (D-NN) to the brainstorm.
• specflo spec start [--json] - create (or locate) the active project's spec.md.
• specflo requirement add --text ... --acceptance ... [--from D-NN] [--supersedes REQ-NN] - append a requirement (REQ-NN) to the spec.
• specflo plan start [--json] - create (or locate) the active project's plan.md.
• specflo task add --text ... --acceptance ... --verify ... --from REQ-NN [--from REQ-NN ...] [--depends-on T-NN ...] [--supersedes T-NN] - append a task (T-NN) to the plan. --from (repeatable, required) links to the requirement(s) the task implements; --depends-on (repeatable) declares execution ordering; --acceptance is a behavioural pass/fail criterion; --verify is the command or step to confirm it.
• specflo milestone add --text ... --exit ... [--exit ...] - append a milestone (M-NN) with its Exit checklist to the plan; milestone list and milestone show report rollup and the current milestone.
• specflo validate brainstorm|spec|plan [--json] - lint the phase's artifact and report readiness. The plan lint checks bidirectional REQ<->task coverage, that every task has acceptance + verification, and that dependencies resolve and are acyclic.

Working the plan

• specflo task start <T-NN> / task done <T-NN> - mark a task in_progress / done.
• specflo task block <T-NN> [--reason ...] / task reopen <T-NN> - mark a task blocked (optionally recording why) / return it to pending.
• specflo task list [--json] - all tasks with their progress state and the deps-aware next-actionable marker.
• specflo task show [<T-NN>] [--json] - a task's brief: acceptance criterion, cited requirements, and constraints. Defaults to the next actionable task.
• specflo review start [--json] - mint the next numbered review round (review-N.md) in the project directory and print its path. Numbering only ever goes up, so a deleted round leaves a permanent gap rather than a reused identity. With a round already open, prints that round's path and mints nothing - reusing it is how an abandoned review is resumed.
• specflo review done --verdict ready-to-merge|changes-requested|waived [--reason ...] [--file <path>] [--json] - close the open round by writing the verdict into its frontmatter, stamped with the date and, inside a git repo, the short HEAD sha. waived requires --reason, so a project that skipped review records why. --file ingests a reviewer's report as the round's body, refusing once that body has been written into. specflo never derives staleness from the stamp: commits landing after a closed round change nothing.
• specflo validate execute [--json] - completion gate: confirms every task is done, then that the latest review round closed ready-to-merge or waived. The gate keys on the verdict alone and never on the round's findings, so a passing round may still list nits.
• specflo advance [--json] - validate the current phase's artifact, then move the active project to the next phase (brainstorm -> spec -> plan -> execute).
• specflo reopen [<phase>] - the inverse of advance: move the phase pointer backward (bare reopen goes one phase back, reopen <phase> jumps to a named earlier phase). A pure pointer move; no artifact is rewritten.
• specflo checkpoint [--json] - print the active project's resume prompt (which phase, what to read, what to do next) and refresh checkpoint.md. The file is also rewritten automatically after every state-mutating command, so a freshly-cleared agent can jump back in with one command.

Session-start and unattended runs

• specflo hook reseed [--format text|claude] [--continue] - emit the clear-and-continue payload for the active project: a confirmation-gate directive (do not start work; present the checkpoint and ask whether to continue) followed by the verbatim checkpoint. Prints nothing for no active project. Always exits 0, reads no stdin, makes no network calls - safe to wire into a session-start hook unconditionally.
  • --format claude wraps the payload as Claude Code SessionStart JSON: the payload as additionalContext (re-grounds the agent) plus a user-visible systemMessage that tells you what to type to kick it off (Claude can't make the agent take a turn on its own). The default --format text stays portable plain text for any harness.
  • --continue swaps the confirmation gate for a direct carry out the next step now directive, and inlines the current task's brief - for a caller that cleared context on purpose and has already answered "keep going".
• specflo hook install - idempotently merge the SessionStart wiring into Claude Code's .claude/settings.json, preserving all existing content; a previously-installed (older) reseed entry is rewired in place rather than duplicated. The wiring calls specflo hook reseed --format claude on the startup, clear, and resume sources (compact excluded - its digest is retained).
• specflo hook print - print that same wiring as a JSON fragment on stdout (pipeable), either to merge into Claude Code's settings yourself or as a starting point to adapt for another harness (opencode, OpenAI Codex, ...); a stderr note marks it as a fragment and points at specflo hook install as the safe merge. pi needs no wiring - the bundled pi extension reseeds on its own (see The pi extension). (hook print --install remains as a deprecated alias of hook install.)
• specflo auto [--autonomy safe|autonomous|yolo] [--max-passes N] [--off|--on] [--json] - emit the auto-mode handoff payload: an explicit, per-invocation opt-in that starts or continues an unattended run from the current phase toward project completion, emitting a bootstrap directive (autonomy policy + guardrail stop-conditions) instead of the ask-first pause. specflo only prints the payload - it drives no loop, spawns no nested agent, and never clears context; the clear-and-reseed trigger is the outer harness's job. Strictly additive - the default hook reseed / checkpoint behavior is unchanged.
  • --autonomy sets how far it runs unattended: safe (the default) and autonomous stop and hand off on any irreversible or outbound step; yolo permits them. Overrides the .specflo config default.
  • --max-passes is a runaway backstop: each invocation counts as one pass in a durable per-project run-state file, and on reaching the cap (default 50) the run escalates to the human instead of continuing. Overrides the config default.
  • --off sets the durable kill switch (the next pass halts); --on clears it.
  • --json reports the pass as an object - its payload text, a boolean stop, and the reason that stopped it (kill-switch, pass-cap, stall, project-complete, or unavailable; null while the run continues) - so a machine caller reads loop control from the CLI instead of deciding it.

Harness integration

• specflo skills install|status|update|uninstall [--scope user|project] [--harness NAME[:SCOPE]] - install specflo's bundled workflow skills into the agent harnesses on your machine, and keep them current. See Skills.
• specflo extension install [--scope user|project] - install the bundled pi extension into pi's extension directory: ~/.pi/agent/extensions/specflo by default, ./.pi/extensions/specflo with --scope project. A plain local copy with a version stamp - no npm, no network - and pi discovers the directory on its own, so no pi settings are read or written. Re-run to update. See The pi extension.

The config file

.specflo/config.yaml is written by specflo init and documents itself. Every
setting specflo has appears in it: live as key: value once set, commented out
at its shipped default while it is not, each under a one-line description. So
the file lists what you can change without a trip to the docs, and config set
is literally uncommenting a line you can already see.

# Where project artifacts live, relative to the repo root.
projects_dir: docs/projects

# The project every command acts on; set it with `specflo switch`.
active_project: my-thing

# Default autonomy level for `specflo auto`: safe, autonomous or yolo.
# autonomy: safe

# Runaway backstop: the most passes one `specflo auto` run may take.
# auto_max_passes: 50

# Percent of the context window at which the pi extension arms clear-and-continue.
# context_threshold_percent: 25

It is your file, so specflo writes it conservatively:

• A comment you wrote, the key order you chose, and a key specflo has never
  heard of all survive every write.
• Reading never writes. specflo status --json, which the pi extension polls
  every turn, leaves the bytes identical.
• A config written before a setting existed gains it on the next write,
  commented out at its default, announced by one note on stderr naming what was
  added.
• A value the file sets but specflo cannot accept degrades to the shipped
  default with a warning, rather than breaking every command that loads it.
  specflo config list marks that key (invalid, using default).

Edit the file by hand or go through specflo config - the commands validate
before writing, which the editor cannot.

Session-start integration (clear-and-continue)

An agent can't clear its own context or remember what to do across a /clear -
the continuation must come from outside the conversation. specflo hook reseed
is that bridge: install it once (specflo hook install), and on a fresh start,
after a /clear, or when you resume a session, Claude Code reorients from the
on-disk checkpoint and asks before resuming, so you never re-explain where
you were. Because a SessionStart hook can re-ground the agent but cannot make
it speak first, the wiring also surfaces a short visible systemMessage
telling you what to type (e.g. continue) to start the hand-off.

The installed wiring is Claude Code's. The payload itself is portable: another
harness (opencode, OpenAI Codex, ...) can call the plain-text
specflo hook reseed from its own session-start mechanism and inject the
output as context. pi is the exception - it needs no wiring at all, because the
bundled pi extension injects the reseed itself (see
The pi extension).

Security posture: the reseed injects only trusted local state - the
checkpoint is derived read-only from the project's own artifacts, never from
external or network input - so running it at session start is benign.

The pi extension

For the pi coding agent, specflo goes further than the hook: a bundled pi
extension performs the clear itself. It is a thin driver by design - every
piece of state it acts on is the stdout of a specflo command, it keeps no
durable state of its own, registers no model-callable tool, and never blocks a
tool call. Install it once (pi 0.81+):

specflo extension install                  # -> ~/.pi/agent/extensions/specflo
specflo extension install --scope project  # -> ./.pi/extensions/specflo

pi discovers the directory on its own - nothing else to wire. Re-running is
safe: an up-to-date install is reported as current, a stale one is replaced
whole.

In an attended pi session:

• Cold start. When pi starts or resumes inside a specflo repo, the first
  turn is seeded with the specflo hook reseed payload, so the agent already
  knows where the project stands and asks before resuming. With no active
  project it injects nothing.
• Arming. At each turn's end the extension reads pi's own context-usage
  percent and arms once it reaches context_threshold_percent (default 25,
  set in .specflo/config.yaml). Arming is not firing: the next specflo seam
  fires it, so the effective clear point is that percent plus one task's worth
  of context.
• The seam. While armed it watches specflo status --json for a safe
  point to clear: the phase advancing, or a task reaching done. A task merely
  in progress is never a seam, so in-flight work is never discarded.
• The notice. An armed seam produces one passive notice naming the current
  usage, the seam that fired, and the command to run. Nothing clears on its
  own in an attended session.
• /specflo-continue. Clears the session and reseeds the
  direct-continuation payload - the checkpoint plus the current task brief -
  so the fresh session carries straight on.

In an auto run:

• /specflo-continue auto starts or continues an unattended run from
  inside pi - the same explicit opt-in specflo auto is, counting a pass in
  the same run state - and delivers that pass's payload into a fresh session.
• The unattended fire. After one clear has run, every armed seam clears
  and reseeds by itself: the extension fetches the next specflo auto pass
  and delivers its payload verbatim. No dialog, no confirmation, no input.
• Joining a run cold. If the run was started outside pi (specflo auto in
  a terminal, then pi opened), the first armed seam prints a bootstrap notice
  asking you to type /specflo-continue auto once; every seam after that is
  unattended.
• Stopping. Loop control lives in the CLI, never the extension: on the
  kill switch (specflo auto --off), the pass cap, a stall, or project
  completion, nothing clears and the CLI's own stop directive is shown as a
  notice. specflo auto --on clears the kill switch again.

Skills

specflo ships its seven workflow skills inside the package and installs them into
whatever agent harness it finds on your machine (Claude Code, pi, Hermes,
opencode). Let the CLI do it - no copying or symlinking by hand:

specflo skills install     # into the user skills dir of every detected harness
specflo skills status      # what is installed, and whether it is current
specflo skills update      # bring stale installs up to the bundled version
specflo skills uninstall   # remove the ones specflo's stamp owns

On an interactive terminal, install asks which harnesses and scopes to use;
pass --no-input (with --harness/--scope) to script it. Every verb takes
--scope user|project - user (the default) is the harness's user-level skills
dir such as ~/.claude/skills/, and project is the repo-local one such as
./.claude/skills/ - plus a repeatable --harness NAME[:SCOPE] to target one
harness instead of all detected ones.

Each install is a plain copy carrying a specflo provenance stamp, so update and
uninstall only ever touch skills specflo itself installed, and a skill you have
edited locally is never overwritten without --force. When an installed skill
falls behind the bundled version, any specflo command prints a single advisory
line on stderr pointing at specflo skills update. It is notice-only: it never
prompts, never updates anything, and never changes the exit code. Silence it by
setting CI or AGENTSQUIRE_NO_UPDATE_CHECK.

The seven skills:

• specflo-brainstorm (skills/specflo-brainstorm/SKILL.md) - drives the brainstorm phase over the CLI above (one question at a time, captures decisions, validates, hands off to the spec phase).
• specflo-spec (skills/specflo-spec/SKILL.md) - drives the spec phase (synthesize testable REQ-NN requirements from the brainstorm, validate, hand off to the plan phase).
• specflo-plan (skills/specflo-plan/SKILL.md) - drives the plan phase (decompose the validated spec into dependency-ordered, testable T-NN tasks, validate, hand off to the execute phase).
• specflo-execute (skills/specflo-execute/SKILL.md) - drives the execute phase (work tasks one at a time with task show/task start/task done, run the final whole-branch review in fresh context and record it with review start/review done, validate with validate execute, complete the project with advance).
• specflo-research (skills/specflo-research/SKILL.md) - a research subagent the specflo-brainstorm skill dispatches to ground decisions in current facts: an upfront landscape scan (what tools/SDKs/clients/frameworks already exist) plus opportunistic assumption-checks. Wiki-integrated - searches the Agent Wiki first and saves findings back (soft dependency).
• specflo-shelve (skills/specflo-shelve/SKILL.md) - recognizes "park this for now" / "let's pick that back up" and maps them to specflo shelve and specflo resume, so a project can be set aside and reclaimed without losing its phase or artifacts.
• specflo-auto (skills/specflo-auto/SKILL.md) - recognizes an unattended-run intent ("auto mode", "autopilot", "keep going without me") and maps it to specflo auto, then follows the emitted payload. Thin by design: the CLI carries the loop, autonomy policy, and guardrails; the skill only triggers it and hands the directives to the loop.

Working on the skills themselves

If you are editing specflo's own skills from a checkout, symlink them instead so
your edits take effect immediately. specflo recognizes a symlinked live-edit
install and stays quiet about updates for it:

ln -s "$PWD/skills/specflo-brainstorm" ~/.claude/skills/specflo-brainstorm

Install from source

From a checkout, with uv installed
(curl -LsSf https://astral.sh/uv/install.sh | sh):

uv tool install .              # install `specflo` globally, from the repo root
uv tool install --reinstall .  # update after pulling changes
uv tool uninstall specflo      # remove

pipx install . and pip install . work the same way if you prefer them.

To build distributables instead, uv build writes the wheel and sdist into
dist/; install the wheel anywhere with
uv tool install ./dist/specflo-<version>-py3-none-any.whl (no source checkout
needed).

Development

uv sync                    # create the venv and install deps (incl. dev group)
uv run pytest              # run the tests
uv run specflo --help      # run the CLI without installing it

License

GPL-3.0-or-later. Copyright (C) 2026 TacoTakumi.