| 1 | package engine |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "os" |
| 9 | "os/exec" |
| 10 | "path/filepath" |
| 11 | "runtime" |
| 12 | "strconv" |
| 13 | "strings" |
| 14 | "time" |
| 15 | ) |
| 16 | |
| 17 | // DefaultPythonBinary is the interpreter we look up unless RunOptions |
| 18 | // overrides it. Windows installs may expose only "python"; we surface a |
| 19 | // clear error in that case rather than silently picking the wrong binary. |
| 20 | const DefaultPythonBinary = "python3" |
| 21 | |
| 22 | // MinPythonVersion mirrors the engine's MIN_PYTHON constant in |
| 23 | // last30days.py. Surfaced in errors so users know what they're missing. |
| 24 | const MinPythonVersion = "3.12" |
| 25 | |
| 26 | // PythonInstallURL is included in the missing-interpreter error so users |
| 27 | // have a direct route from the failure to a fix. |
| 28 | const PythonInstallURL = "https://www.python.org/downloads/" |
| 29 | |
| 30 | // DefaultTimeout caps a single research subprocess. The engine's deep mode |
| 31 | // can run several minutes; five minutes is a safe upper bound that still |
| 32 | // fails fast when something hangs. |
| 33 | const DefaultTimeout = 5 * time.Minute |
| 34 | |
| 35 | // TimeoutEnvOverride lets operators override DefaultTimeout per install |
| 36 | // (seconds, integer). Honored by Run when RunOptions.Timeout is zero. |
| 37 | const TimeoutEnvOverride = "LAST30DAYS_MCP_TIMEOUT" |
| 38 | |
| 39 | // RunOptions configures one invocation of the embedded Python engine. |
| 40 | // PythonPath is exposed so tests can substitute a stub interpreter without |
| 41 | // manipulating the process PATH. |
| 42 | type RunOptions struct { |
| 43 | PythonPath string // resolved python3 binary; empty means look up DefaultPythonBinary on PATH |
| 44 | CacheDir string // engine.Ensure result; lib/ here is added to PYTHONPATH |
| 45 | Args []string // arguments after last30days.py (topic, --emit=..., etc.) |
| 46 | ExtraEnv []string // appended to os.Environ() for the child process |
| 47 | Timeout time.Duration // zero means DefaultTimeout or TimeoutEnvOverride |
| 48 | } |
| 49 | |
| 50 | // RunResult captures the engine's full output. Stdout is what we surface to |
| 51 | // the agent; Stderr is included in error messages so users can diagnose |
| 52 | // engine failures without leaving Claude Desktop. |
| 53 | type RunResult struct { |
| 54 | Stdout []byte |
| 55 | Stderr []byte |
| 56 | ExitCode int |
| 57 | TimedOut bool |
| 58 | } |
| 59 | |
| 60 | // Run shells out to python3 with last30days.py inside cacheDir. The child |
| 61 | // receives the parent environment (so MCPB user_config env-injection |
| 62 | // reaches the engine) plus ExtraEnv and a PYTHONPATH that points at the |
| 63 | // cache so the engine's `from lib import ...` statements resolve. |
| 64 | // |
| 65 | // A missing interpreter, a non-zero exit, and a timeout each surface as |
| 66 | // distinct errors so the tool handler can map them to user-facing |
| 67 | // messages without re-parsing stderr. |
| 68 | func Run(ctx context.Context, opts RunOptions) (*RunResult, error) { |
| 69 | if opts.CacheDir == "" { |
| 70 | return nil, errors.New("engine: CacheDir is required") |
| 71 | } |
| 72 | pythonPath, err := resolvePython(opts.PythonPath) |
| 73 | if err != nil { |
| 74 | return nil, err |
| 75 | } |
| 76 | |
| 77 | scriptPath := filepath.Join(opts.CacheDir, "last30days.py") |
| 78 | if _, err := os.Stat(scriptPath); err != nil { |
| 79 | return nil, fmt.Errorf("engine: last30days.py not found in cache %s: %w", opts.CacheDir, err) |
| 80 | } |
| 81 | |
| 82 | timeout := resolveTimeout(opts.Timeout) |
| 83 | subCtx, cancel := context.WithTimeout(ctx, timeout) |
| 84 | defer cancel() |
| 85 | |
| 86 | args := append([]string{scriptPath}, opts.Args...) |
| 87 | cmd := exec.CommandContext(subCtx, pythonPath, args...) |
| 88 | cmd.Env = buildEnv(opts.CacheDir, opts.ExtraEnv) |
| 89 | |
| 90 | var stdout, stderr bytes.Buffer |
| 91 | cmd.Stdout = &stdout |
| 92 | cmd.Stderr = &stderr |
| 93 | |
| 94 | err = cmd.Run() |
| 95 | res := &RunResult{ |
| 96 | Stdout: stdout.Bytes(), |
| 97 | Stderr: stderr.Bytes(), |
| 98 | ExitCode: 0, |
| 99 | TimedOut: errors.Is(subCtx.Err(), context.DeadlineExceeded), |
| 100 | } |
| 101 | if err == nil { |
| 102 | return res, nil |
| 103 | } |
| 104 | |
| 105 | var exitErr *exec.ExitError |
| 106 | if errors.As(err, &exitErr) { |
| 107 | res.ExitCode = exitErr.ExitCode() |
| 108 | if res.TimedOut { |
| 109 | return res, fmt.Errorf("engine: subprocess exceeded %s timeout", timeout) |
| 110 | } |
| 111 | return res, fmt.Errorf("engine: subprocess exited with code %d", res.ExitCode) |
| 112 | } |
| 113 | return res, fmt.Errorf("engine: subprocess failed to start: %w", err) |
| 114 | } |
| 115 | |
| 116 | // resolvePython returns an absolute path to the interpreter or an error |
| 117 | // naming the install URL. If the caller supplied a path we trust it - tests |
| 118 | // rely on this to inject a stub. Otherwise we look up python3 on PATH. |
| 119 | func resolvePython(override string) (string, error) { |
| 120 | if override != "" { |
| 121 | return override, nil |
| 122 | } |
| 123 | path, err := exec.LookPath(DefaultPythonBinary) |
| 124 | if err == nil { |
| 125 | return path, nil |
| 126 | } |
| 127 | return "", fmt.Errorf( |
| 128 | "engine: %s not found on PATH (need Python %s+, install from %s; current GOOS=%s)", |
| 129 | DefaultPythonBinary, MinPythonVersion, PythonInstallURL, runtime.GOOS, |
| 130 | ) |
| 131 | } |
| 132 | |
| 133 | func resolveTimeout(explicit time.Duration) time.Duration { |
| 134 | if explicit > 0 { |
| 135 | return explicit |
| 136 | } |
| 137 | if raw := os.Getenv(TimeoutEnvOverride); raw != "" { |
| 138 | if d, err := time.ParseDuration(raw); err == nil && d > 0 { |
| 139 | return d |
| 140 | } |
| 141 | // Accept bare integer seconds (e.g. "300") as documented. |
| 142 | if secs, err := strconv.Atoi(raw); err == nil && secs > 0 { |
| 143 | return time.Duration(secs) * time.Second |
| 144 | } |
| 145 | } |
| 146 | return DefaultTimeout |
| 147 | } |
| 148 | |
| 149 | // buildEnv stitches PYTHONPATH onto os.Environ + ExtraEnv. Any pre-existing |
| 150 | // PYTHONPATH in the parent environment is dropped before appending the |
| 151 | // cache dir; otherwise the child sees two PYTHONPATH= entries and POSIX |
| 152 | // getenv returns the first one, so the user's value wins and the engine's |
| 153 | // `from lib import ...` fails with ModuleNotFoundError. The engine is |
| 154 | // self-contained and does not need the user's Python module search path. |
| 155 | func buildEnv(cacheDir string, extra []string) []string { |
| 156 | const pyKey = "PYTHONPATH=" |
| 157 | parent := os.Environ() |
| 158 | base := make([]string, 0, len(parent)+1+len(extra)) |
| 159 | for _, kv := range parent { |
| 160 | if strings.HasPrefix(kv, pyKey) { |
| 161 | continue |
| 162 | } |
| 163 | base = append(base, kv) |
| 164 | } |
| 165 | base = append(base, pyKey+cacheDir) |
| 166 | base = append(base, extra...) |
| 167 | return base |
| 168 | } |
| 169 |