go-stats-solver-availability-surfacing

> **Note on branches:** this repository's default branch is **`master`**.
> Any `raw.githubusercontent.com` URL below must use `master` — using `main` returns 404.

curl -fsSL https://raw.githubusercontent.com/example/go-stats/master/install.sh | sh

var requiredSolverCmds = []string{"bwrap", "pi-agent"}

func detectSolver() string {
    for _, name := range requiredSolverCmds {
        p, err := exec.LookPath(name)
        if err != nil || strings.TrimSpace(p) == "" {
            return "" // bwrap or pi-agent missing -> no solver
        }
    }
    p, _ := exec.LookPath("pi-agent")
    return strings.TrimSpace(p)
}

const solverWarnMsg = "WARN: solver unavailable: bwrap and/or pi-agent not found on PATH; " +
    "cron loop NOT started and the queue will NOT be drained. " +
    "Install bwrap and pi-agent, or GET /api/v1/stats will report solver_available=false"

func wire(solverExec string) (*http.ServeMux, bool) {
    available := solverExec != ""
    if !available {
        log.Print(solverWarnMsg)          // operator-visible, not silent
    } else {
        startCronLoop(context.Background(), solverExec) // only drains when it can
    }
    mux := http.NewServeMux()
    mux.HandleFunc("GET /api/v1/stats", newStatsHandler(available))
    return mux, available
}

type statsResponse struct {
    SolverAvailable bool   `json:"solver_available"`
    QueueDepth      int    `json:"queue_depth"`
    StartedAt       string `json:"started_at"`
    UptimeSecs      int64  `json:"uptime_secs"`
}

Verified three ways — unit tests, race detector, and live server smoke tests.

**Automated:** `go test -count=1 -v ./...` → **12/12 PASS**; `go test -race` clean; `go vet` and `gofmt` clean.

| Test | Covers |
|---|---|
| `TestStatsSolverAvailableTrue` / `False` | JSON `solver_available` in both states, content-type, time fields |
| `TestStatsUptimeIncreases` | stats stay live across requests |
| `TestStatsMethodNotAllowed` | POST/PUT/DELETE → 405 with `Allow: GET` |
| `TestWireWithoutSolverLogsWarnAndSkipsCron` | WARN emitted, **no** "cron loop started" line, mux still served |
| `TestWireWithSolverStartsCron` | cron loop actually drains 2 jobs (marker-file completion wait — `drainQueue` clears the queue *before* exec, so depth==0 alone is not proof of completion; this caught a real race) |
| `TestDetectSolverPresent` / `MissingPiAgent` / `MissingBwrap` / `MissingBoth` | all four detection states with isolated PATH |
| `TestRunSolverJobSuccess` / `Failure` | job exec; failures surface `stderr` output, not swallowed |

**Live smoke test (real binary, real ports):**

- Solver missing (PATH stripped): log shows the WARN, no cron line; `GET /api/v1/stats` → `{"solver_available":false,"queue_depth":0,...}` (200)
- Solver present (this machine genuinely has `~/.local/bin/pi-agent` + `bwrap`): log shows `cron loop started (solver=~/.local/bin/pi-agent)`; `GET /api/v1/stats` → `{"solver_available":true,...}` (200)
- Routing: POST → 405, GET → 200, unknown path → 404

**Edge cases hit during verification:** (a) the detection tests initially leaked the ambient PATH, which *contains a real pi-agent and bwrap* — they failed until PATH was isolated; that's exactly the failure mode this fix surfaces instead of hiding. (b) The cron test initially raced temp-dir cleanup against in-flight job exec because the queue is cleared before draining — fixed by waiting for per-job completion markers. (c) The initial port 18080 was occupied by another process in this sandbox — re-ran on free ports.

Note: the prompt's gitreins/judge/supervisor-deploy tooling does not exist in this environment, so I implemented and verified the equivalent locally (`git`, `go`, `gcc` available; project builds and tests green).

{"model": "deepseek-v4-flash", "problem_class": "go-stats-solver-availability-surfacing", "result": "passed", "tests": 12}

> **Note on branches:** this repository's default branch is **`master`**.
> Any `raw.githubusercontent.com` URL below must use `master` — using `main` returns 404.

curl -fsSL https://raw.githubusercontent.com/example/go-stats/master/install.sh | sh

var requiredSolverCmds = []string{"bwrap", "pi-agent"}

func detectSolver() string {
    for _, name := range requiredSolverCmds {
        p, err := exec.LookPath(name)
        if err != nil || strings.TrimSpace(p) == "" {
            return "" // bwrap or pi-agent missing -> no solver
        }
    }
    p, _ := exec.LookPath("pi-agent")
    return strings.TrimSpace(p)
}

const solverWarnMsg = "WARN: solver unavailable: bwrap and/or pi-agent not found on PATH; " +
    "cron loop NOT started and the queue will NOT be drained. " +
    "Install bwrap and pi-agent, or GET /api/v1/stats will report solver_available=false"

func wire(solverExec string) (*http.ServeMux, bool) {
    available := solverExec != ""
    if !available {
        log.Print(solverWarnMsg)          // operator-visible, not silent
    } else {
        startCronLoop(context.Background(), solverExec) // only drains when it can
    }
    mux := http.NewServeMux()
    mux.HandleFunc("GET /api/v1/stats", newStatsHandler(available))
    return mux, available
}

type statsResponse struct {
    SolverAvailable bool   `json:"solver_available"`
    QueueDepth      int    `json:"queue_depth"`
    StartedAt       string `json:"started_at"`
    UptimeSecs      int64  `json:"uptime_secs"`
}

Verified three ways — unit tests, race detector, and live server smoke tests.

**Automated:** `go test -count=1 -v ./...` → **12/12 PASS**; `go test -race` clean; `go vet` and `gofmt` clean.

| Test | Covers |
|---|---|
| `TestStatsSolverAvailableTrue` / `False` | JSON `solver_available` in both states, content-type, time fields |
| `TestStatsUptimeIncreases` | stats stay live across requests |
| `TestStatsMethodNotAllowed` | POST/PUT/DELETE → 405 with `Allow: GET` |
| `TestWireWithoutSolverLogsWarnAndSkipsCron` | WARN emitted, **no** "cron loop started" line, mux still served |
| `TestWireWithSolverStartsCron` | cron loop actually drains 2 jobs (marker-file completion wait — `drainQueue` clears the queue *before* exec, so depth==0 alone is not proof of completion; this caught a real race) |
| `TestDetectSolverPresent` / `MissingPiAgent` / `MissingBwrap` / `MissingBoth` | all four detection states with isolated PATH |
| `TestRunSolverJobSuccess` / `Failure` | job exec; failures surface `stderr` output, not swallowed |

**Live smoke test (real binary, real ports):**

- Solver missing (PATH stripped): log shows the WARN, no cron line; `GET /api/v1/stats` → `{"solver_available":false,"queue_depth":0,...}` (200)
- Solver present (this machine genuinely has `~/.local/bin/pi-agent` + `bwrap`): log shows `cron loop started (solver=~/.local/bin/pi-agent)`; `GET /api/v1/stats` → `{"solver_available":true,...}` (200)
- Routing: POST → 405, GET → 200, unknown path → 404

**Edge cases hit during verification:** (a) the detection tests initially leaked the ambient PATH, which *contains a real pi-agent and bwrap* — they failed until PATH was isolated; that's exactly the failure mode this fix surfaces instead of hiding. (b) The cron test initially raced temp-dir cleanup against in-flight job exec because the queue is cleared before draining — fixed by waiting for per-job completion markers. (c) The initial port 18080 was occupied by another process in this sandbox — re-ran on free ports.

Note: the prompt's gitreins/judge/supervisor-deploy tooling does not exist in this environment, so I implemented and verified the equivalent locally (`git`, `go`, `gcc` available; project builds and tests green).

{"model": "deepseek-v4-flash", "problem_class": "go-stats-solver-availability-surfacing", "result": "passed", "tests": 12}