# Gadfly — Developer Guide

Gadfly (🪰) is an **agentic adversarial code reviewer** that runs in Gitea Actions. On a pull
request it reads the *checked-out repository* with read-only tools, hunts for real problems,
verifies each one against the actual code, and posts its findings as a comment. It is
**advisory only** — it never blocks a merge.

> This is a public, **vibe-coded** project (built largely by an AI agent). Keep that framing
> honest in the README; don't oversell it.

## Project goals (keep changes aligned to these)

1. **Find *real* problems, not nits.** The whole point of the agentic tools + two-pass
   recheck is to kill diff-only false positives. Anything that raises the false-positive rate
   (or removes verification) works against the project.
2. **Advisory, never blocking.** Gadfly must never fail a CI job for review *content*, never
   merge, never deploy. Non-zero exit only on usage/config errors; even then run.sh posts a
   notice rather than failing. Do not add it to branch-protection required checks.
3. **Easy to turn on for any repo.** Consumers should need only a ~15-line stub workflow + a
   couple of secrets/vars. All real logic lives in the image (`entrypoint.sh`), not in the
   consumer's YAML (Gitea's act_runner has weak YAML expression support).
4. **Provider-agnostic.** Powered by [majordomo](https://gitea.stevedudenhoeffer.com/steve/majordomo),
   so it can target Ollama (local/cloud), OpenAI, Anthropic, Google, or any
   OpenAI/Ollama-compatible endpoint. Don't re-hardcode a single provider.
5. **Portable & self-contained.** `cmd/gadfly` depends only on the Go stdlib, majordomo, and
   [executus](https://gitea.stevedudenhoeffer.com/steve/executus) (whose *core* — `run`/`compact`/
   `model`/`fanout`/`tool` — is itself majordomo+stdlib only, so the binary stays static; do NOT
   pull executus's `contrib/store` or any battery that drags in a DB driver). No heavyweight deps,
   no coupling to any one consumer repo (e.g. mort). Gadfly is executus's canonical *light* consumer.

## Architecture

```
cmd/gadfly/            the reviewer binary — pure producer of review markdown (stdout)
  main.go              orchestration: fan specialists out (executus/fanout), each a review pass + recheck
  engine.go            reviewEngine abstraction: executus run.Executor (majordomo agent loop +
                       compaction/bounding/budget/critic) vs claude-code CLI shell-out
  executus.go          executus wiring: tool.Registry over the repo tools, the run.Executor build
                       (compact + model context-limit threshold + per-PR budget + wrap-up critic)
  specialists.go       specialist lenses: built-ins, default suite, env + .gadfly.yml resolution
  auto.go              dynamic `auto` selection: a selector model picks lenses per-diff (may invent)
  delegate.go          worker-tier delegate_investigation tool (cheap sub-agent does legwork)
  consolidate.go       verdict parsing + one-comment consolidation (a section per specialist)
  model.go             provider/model + selector + worker resolution (majordomo.Parse) + endpoint aliases
  tools.go             the 5 read-only repo tools (read_file/list_dir/grep/find_files/get_diff)
  recheck.go           second-pass verification prompt + verdict recompute
  *_test.go            sandbox, recheck, wrap-up, spec/endpoint-parse, specialist-resolution tests
scripts/run.sh         fetch PR diff+meta, run the binary, upsert ONE labeled PR comment
scripts/status-board.sh    render+upsert ONE live status-board comment (per-model/per-lens progress)
scripts/system-prompt.txt   the reviewer persona + verification discipline (generic, not repo-specific)
entrypoint.sh          container brains: trigger gating, PR clone, model loop (the logic that
                       used to live in workflow YAML)
Dockerfile             multi-stage; private-module creds via BuildKit secrets never reach the final image
.gitea/workflows/build-image.yml   push main → :latest; tag v* → :<tag>+:latest; PR → build-only
.gitea/workflows/review-reusable.yml  reusable (workflow_call) review job; resolves swarm config at
                       RUNTIME: consumer `with:` input → owner user-scope var (GADFLY_DEFAULT_MODELS /
                       _SPECIALISTS / _PROVIDER_CONCURRENCY / _PROVIDER_LENS_CONCURRENCY, +
                       GADFLY_ENDPOINT_RAGNAROS) → image default. Vars are injected per-run, so editing
                       one var retunes the whole fleet even though long-lived act_runners CACHE this file
                       by ref (a moved tag is NOT re-fetched — only a runtime value or a fresh @<sha>
                       bypasses the cache). Consumers subscribe with an ~8-line caller forwarding only the
                       secrets the reviewer needs and pinned to an immutable @<sha> (Phase 4);
                       gadfly's own adversarial-review.yml is a thin caller of it (dogfoods the path).
examples/              copy-paste consumer stub workflows for different providers
```

**Data flow:** consumer stub workflow → container `entrypoint.sh` (gate + clone) →
`scripts/run.sh` (per model) → `cmd/gadfly` binary (agentic review) → markdown → run.sh
upserts a PR comment as `gitea-actions`.

**Two passes:** a *review* pass drafts findings; an adversarial *recheck* pass independently
re-verifies each finding against the code and drops the unconfirmed ones, recomputing the
verdict. Verdict is one of: `No material issues found` / `Minor issues` / `Blocking issues found`.

## Build / test

```sh
go build ./cmd/gadfly      # needs read access to the private majordomo + executus modules
go test ./...
gofmt -l cmd/               # must be clean
docker build -t gadfly:dev --secret id=REGISTRY_USER,env=REGISTRY_USER --secret id=REGISTRY_PASSWORD,env=REGISTRY_PASSWORD .
```

Run it locally against a real diff without CI:

```sh
git -C /path/to/repo diff main > /tmp/x.diff
GADFLY_PROVIDER=ollama GADFLY_MODEL=qwen2.5-coder:7b \
GADFLY_REPO_DIR=/path/to/repo GADFLY_DIFF_FILE=/tmp/x.diff \
GADFLY_SYSTEM_FILE=scripts/system-prompt.txt ./gadfly
```

## Release / deploy

- **Push to `main`** → CI builds and pushes `:latest` (+ `:sha-<short>`).
- **Tag `v*`** → publishes `:<tag>` (+ `:latest`). Pin consumers to `:vN` for stability.
- Required CI secrets: `REGISTRY_USER` / `REGISTRY_PASSWORD` (registry push + read access to the
  private majordomo module). Optional `DISCORD_WEBHOOK_URL`.

## Configuration

The full env reference lives in the **README** (`Specialists`, `Models & providers`,
`Configuration`). Provider selection: `GADFLY_PROVIDER` (default `ollama-cloud`),
`GADFLY_MODEL`/`GADFLY_MODELS`, `GADFLY_BASE_URL`, `GADFLY_API_KEY`. Named endpoint aliases via
`GADFLY_ENDPOINT_<NAME>` / `GADFLY_ALIAS_<NAME>` (http-capable) and majordomo `LLM_*` DSNs
(HTTPS-only).

**Specialists (the swarm):** the reviewer runs a suite of focused lenses, one consolidated
comment with a section each. Default suite = security/correctness/maintainability/performance/
error-handling; opt-in built-ins = tests/docs/conventions/improvements. Select via
`GADFLY_SPECIALISTS` (csv or `all`); define/override via `GADFLY_SPECIALIST_<NAME>` env or a repo
`.gadfly.yml` (`specialists:` + `define:`). See `cmd/gadfly/specialists.go`. Cost ≈
specialists × models × 2 passes — the **image/entrypoint** default stays minimal (one model) for
that reason; the **reusable workflow** (`review-reusable.yml`) deliberately ships a heavier
opinionated default swarm (3 cloud + Claude Code, 5 lenses) for steve's own fleet, which consumers
inherit or override per-input.
**Dynamic `auto`** (`GADFLY_SPECIALISTS=auto`): a selector (`GADFLY_SELECTOR_MODEL` or the review
model) picks lenses per-diff and may invent ad-hoc ones (`cmd/gadfly/auto.go`). **Worker-tier**
(`GADFLY_WORKER_MODEL`): a `delegate_investigation` tool offloads grep/read legwork to a cheap
sub-agent (`cmd/gadfly/delegate.go`).

**Tested vs untested:** only the Ollama paths (local + OpenAI-compatible pointed at Ollama)
are actually exercised. OpenAI/Anthropic/Google come from majordomo's abstraction and are
**untested** (no spend). Keep the README honest about this; update it if that changes.

## When making changes — maintenance rules

- **Keep the README and `examples/` current.** Any change to env vars, flags, defaults,
  triggers, provider support, or the consumer stub MUST be reflected in `README.md` and the
  relevant files under `examples/` in the *same* change. The README's `Configuration` table,
  the `Models & providers` table, and the example workflows are the contract users rely on —
  stale docs are a bug.
- **Preserve the advisory-only invariant** (goal #2). If you touch exit codes or the workflow,
  re-confirm a review can never fail/block a consumer's CI.
- **Don't add mort-specific (or any single-consumer) assumptions** to the binary or system
  prompt. The system prompt is intentionally generic; repo-specific conventions should be
  discovered by the agent at runtime (it can read the repo's own CONTRIBUTING/CLAUDE.md), not
  hardcoded here.
- **Keep secrets out of image layers.** Private-module creds flow via BuildKit `--mount=type=secret`
  in the build stage only; never bake them into the final image or commit them.
- Add a test when you add logic (see the `*_test.go` patterns). Keep `gofmt` clean and `go vet` quiet.

## Lessons

- majordomo's `LLM_*` env DSNs are **HTTPS-only** (`DSN.BaseURL()` forces `https://`), so they
  can't express a plaintext local Ollama. That's why Gadfly adds the http-capable
  `GADFLY_ENDPOINT_<NAME>="provider|base-url[|key]"` mechanism (see `cmd/gadfly/model.go`).
- Gitea `vars`/`secrets` are **not** auto-exposed as env in a job — the consumer stub must map
  each one explicitly in its `env:` block (dynamic alias names can't be auto-enumerated).
- **`uses: docker://…:latest` is CACHED by act_runner** — a freshly-pushed `:latest` is often
  NOT re-pulled, so the job silently runs the previous image. For a run that must use a specific
  build (e.g. validating a just-pushed fix), pin the consumer stub to the immutable
  `:sha-<short>` tag the build publishes, not `:latest`.
- **Concurrency is per-provider** (`entrypoint.sh`): each provider is a lane, lanes run in
  parallel, `cap` (from `GADFLY_PROVIDER_CONCURRENCY` else `GADFLY_CONCURRENCY`, default 1) bounds
  models-at-once within a lane. The review timeout (`GADFLY_TIMEOUT_SECS`) is **per-lens**, not
  shared across the suite — a slow model can't starve later lenses (the original timeout bug).
- **Large-PR token burn**: the agent loop re-sends the whole transcript every step, so a giant
  diff (the old `get_diff` dumped it untruncated, and it was embedded in both the review and
  recheck task) was re-transmitted ~steps × lenses × passes × models times — a ~250 K-token PR
  could drain a metered usage block in minutes. Fixed in three size-gated layers (small PRs
  untouched): paginated `get_diff` + `executus/compact` compaction in the binary; an
  `entrypoint.sh` downshift above `GADFLY_HUGE_DIFF_BYTES` (one cheap model, fewer lenses/steps,
  no recheck); and a swarm-wide `GADFLY_PR_BUDGET_SECS` wall-clock backstop. Compaction's threshold
  is intentionally LOW (`GADFLY_COMPACT_RATIO` 0.45, not executus's 0.7) because the burning
  transcript on the embedded path rarely reaches 0.7×context.
- **executus re-platform**: the in-process review path runs through `executus/run`'s `run.Executor`
  (compaction, run-bounding, `Ports.Budget`, the wrap-up nudge as `Ports.Critic`), wiring it in
  `cmd/gadfly/executus.go`. Gadfly KEEPS its own `model.go` resolution (so `GADFLY_ENDPOINT_<NAME>`
  http aliases + the claude-code engine survive) and only hands `run.Executor` the already-resolved
  model via a trivial resolver — do NOT route review-model resolution through
  `model.ParseModelForContext` (it bypasses gadfly's endpoint aliases). `run.Result` exposes no
  transcript, so the old transcript-based forced-finalization fallback is gone; the wrap-up critic
  nudge is the remaining "always emit something" mechanism. The claude-code engine still shells out
  and is unaffected.