| 1 | package agent |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "encoding/json" |
| 7 | "fmt" |
| 8 | "slices" |
| 9 | "strings" |
| 10 | "unicode/utf8" |
| 11 | |
| 12 | "reasonix/internal/provider" |
| 13 | "reasonix/internal/tool" |
| 14 | ) |
| 15 | |
| 16 | const ( |
| 17 | // Leave room for the generic tool-result guard to add metadata without |
| 18 | // clipping a task manifest. The aggregate itself owns fair per-task preview |
| 19 | // allocation so every completed child keeps its status and retrieval ref. |
| 20 | subagentAggregateBudgetBytes = maxToolOutputBytes - 512 |
| 21 | subagentResultDefaultBytes = 12 * 1024 |
| 22 | subagentResultMaxBytes = 24 * 1024 |
| 23 | ) |
| 24 | |
| 25 | // SubagentResultTool pages through the retained answer of a persisted |
| 26 | // sub-agent, including partial and retryable failures. Parallel/fleet |
| 27 | // aggregates use this stable reader instead of forcing every child answer |
| 28 | // through one fixed-size tool result. |
| 29 | type SubagentResultTool struct { |
| 30 | store *SubagentStore |
| 31 | workspaceRoot string |
| 32 | } |
| 33 | |
| 34 | func NewSubagentResultTool(task *TaskTool) *SubagentResultTool { |
| 35 | if task == nil { |
| 36 | return &SubagentResultTool{} |
| 37 | } |
| 38 | return &SubagentResultTool{store: task.transcripts, workspaceRoot: task.workspaceRoot} |
| 39 | } |
| 40 | |
| 41 | func (*SubagentResultTool) Name() string { return tool.HostReadSubagentResult } |
| 42 | |
| 43 | func (*SubagentResultTool) Description() string { |
| 44 | return "Read a completed or partial sub-agent's retained answer by the Subagent reference returned from task, parallel_tasks, or fleet. Failed runs may expose their last useful output and an explicit retryability status. Results are scoped to the current conversation lineage and paged by UTF-8 byte offset so large answers remain lossless without overflowing one tool result." |
| 45 | } |
| 46 | |
| 47 | func (*SubagentResultTool) Schema() json.RawMessage { |
| 48 | return json.RawMessage(`{"type":"object","properties":{"ref":{"type":"string","description":"The sa_... value from a Subagent reference line."},"offset_bytes":{"type":"integer","description":"UTF-8 byte offset to start reading from. Omit for the beginning; use next_offset_bytes from the previous page.","minimum":0},"limit_bytes":{"type":"integer","description":"Maximum UTF-8 bytes to return. Defaults to 12288 and is capped at 24576.","minimum":1,"maximum":24576}},"required":["ref"]}`) |
| 49 | } |
| 50 | |
| 51 | func (*SubagentResultTool) ReadOnly() bool { return true } |
| 52 | |
| 53 | func (*SubagentResultTool) PlanModeSafe() bool { return true } |
| 54 | |
| 55 | func (t *SubagentResultTool) Execute(ctx context.Context, args json.RawMessage) (string, error) { |
| 56 | var p struct { |
| 57 | Ref string `json:"ref"` |
| 58 | OffsetBytes int `json:"offset_bytes"` |
| 59 | LimitBytes int `json:"limit_bytes"` |
| 60 | } |
| 61 | dec := json.NewDecoder(bytes.NewReader(args)) |
| 62 | dec.DisallowUnknownFields() |
| 63 | if err := dec.Decode(&p); err != nil { |
| 64 | return "", fmt.Errorf("invalid args: %w", err) |
| 65 | } |
| 66 | p.Ref = strings.TrimSpace(p.Ref) |
| 67 | if p.Ref == "" { |
| 68 | return "", fmt.Errorf("ref is required") |
| 69 | } |
| 70 | if p.OffsetBytes < 0 { |
| 71 | return "", fmt.Errorf("offset_bytes must be non-negative") |
| 72 | } |
| 73 | if p.LimitBytes == 0 { |
| 74 | p.LimitBytes = subagentResultDefaultBytes |
| 75 | } |
| 76 | if p.LimitBytes < 1 || p.LimitBytes > subagentResultMaxBytes { |
| 77 | return "", fmt.Errorf("limit_bytes must be between 1 and %d", subagentResultMaxBytes) |
| 78 | } |
| 79 | if t == nil || t.store == nil { |
| 80 | return "", fmt.Errorf("subagent result storage is not available in this session") |
| 81 | } |
| 82 | parentSession := ParentSession(ctx) |
| 83 | if parentSession == "" { |
| 84 | return "", fmt.Errorf("subagent result retrieval requires a persisted parent session") |
| 85 | } |
| 86 | |
| 87 | answer, status, err := t.store.ReadFinalAnswer(p.Ref, parentSession, t.workspaceRoot) |
| 88 | if err != nil { |
| 89 | return "", err |
| 90 | } |
| 91 | if p.OffsetBytes > len(answer) { |
| 92 | return "", fmt.Errorf("offset_bytes %d exceeds result size %d", p.OffsetBytes, len(answer)) |
| 93 | } |
| 94 | if p.OffsetBytes < len(answer) && !utf8.RuneStart(answer[p.OffsetBytes]) { |
| 95 | return "", fmt.Errorf("offset_bytes %d is not at a UTF-8 character boundary; use next_offset_bytes from the previous page", p.OffsetBytes) |
| 96 | } |
| 97 | end := min(p.OffsetBytes+p.LimitBytes, len(answer)) |
| 98 | for end > p.OffsetBytes && end < len(answer) && !utf8.RuneStart(answer[end]) { |
| 99 | end-- |
| 100 | } |
| 101 | |
| 102 | var b strings.Builder |
| 103 | fmt.Fprintf(&b, "Subagent result %s (status=%s, bytes %d-%d of %d):\n", p.Ref, status, p.OffsetBytes, end, len(answer)) |
| 104 | b.WriteString(answer[p.OffsetBytes:end]) |
| 105 | if end < len(answer) { |
| 106 | fmt.Fprintf(&b, "\n\nMore remains. Call read_subagent_result with ref=%q and offset_bytes=%d.", p.Ref, end) |
| 107 | } else { |
| 108 | b.WriteString("\n\nEnd of subagent result.") |
| 109 | } |
| 110 | return b.String(), nil |
| 111 | } |
| 112 | |
| 113 | // ReadFinalAnswer returns a completed child answer only when the caller owns |
| 114 | // the parent conversation (or a verified descendant) and the workspace still |
| 115 | // matches. The per-ref lock prevents a read racing the terminal transcript save. |
| 116 | func (s *SubagentStore) ReadFinalAnswer(ref, parentSession, workspaceRoot string) (string, SubagentStatus, error) { |
| 117 | if s == nil { |
| 118 | return "", "", fmt.Errorf("subagent result storage is not available") |
| 119 | } |
| 120 | ref = strings.TrimSpace(ref) |
| 121 | parentSession = strings.TrimSpace(parentSession) |
| 122 | if parentSession == "" { |
| 123 | return "", "", fmt.Errorf("subagent result parent session is required") |
| 124 | } |
| 125 | release, err := s.lock(ref) |
| 126 | if err != nil { |
| 127 | return "", "", err |
| 128 | } |
| 129 | defer release() |
| 130 | |
| 131 | meta, err := s.LoadMeta(ref) |
| 132 | if err != nil { |
| 133 | return "", "", err |
| 134 | } |
| 135 | owner := strings.TrimSpace(meta.ParentSession) |
| 136 | if owner != parentSession { |
| 137 | ok, lineageErr := s.isAncestorSession(owner, parentSession) |
| 138 | if lineageErr != nil { |
| 139 | return "", meta.Status, fmt.Errorf("subagent reference %q ownership could not be verified: %w", ref, lineageErr) |
| 140 | } |
| 141 | if !ok { |
| 142 | return "", meta.Status, fmt.Errorf("subagent reference %q does not belong to the current conversation lineage", ref) |
| 143 | } |
| 144 | } |
| 145 | if want := strings.TrimSpace(workspaceRoot); want != "" && strings.TrimSpace(meta.WorkspaceRoot) != want { |
| 146 | return "", meta.Status, fmt.Errorf("subagent reference %q belongs to a different workspace", ref) |
| 147 | } |
| 148 | if meta.Status == SubagentRunning { |
| 149 | return "", meta.Status, fmt.Errorf("subagent reference %q is still in progress", ref) |
| 150 | } |
| 151 | if meta.Status == SubagentInterrupted && meta.Outcome != string(SubagentOutcomeCancelled) { |
| 152 | return "", meta.Status, fmt.Errorf("subagent reference %q was interrupted; only completed or retained partial results can be read", ref) |
| 153 | } |
| 154 | |
| 155 | sess, err := LoadSession(s.sessionPath(ref)) |
| 156 | if err != nil { |
| 157 | return "", meta.Status, fmt.Errorf("load subagent transcript %q: %w", ref, err) |
| 158 | } |
| 159 | msgs := sess.Snapshot() |
| 160 | for _, v := range slices.Backward(msgs) { |
| 161 | if v.Role == provider.RoleAssistant && strings.TrimSpace(v.Content) != "" { |
| 162 | status := meta.Status |
| 163 | if meta.Outcome != "" { |
| 164 | status = SubagentStatus(meta.Outcome) |
| 165 | } |
| 166 | return v.Content, status, nil |
| 167 | } |
| 168 | } |
| 169 | return "", meta.Status, fmt.Errorf("subagent reference %q has no final assistant answer", ref) |
| 170 | } |
| 171 | |
| 172 | type subagentAggregateItem struct { |
| 173 | header string |
| 174 | status string |
| 175 | answer string |
| 176 | ref string |
| 177 | detail string |
| 178 | } |
| 179 | |
| 180 | func formatBoundedSubagentAggregate(prefix string, items []subagentAggregateItem) string { |
| 181 | // Attestations are reserved before prose gets any budget: a long child |
| 182 | // answer must never truncate away what the host saw it change. They |
| 183 | // degrade to header plus violations only if they would starve previews. |
| 184 | prose := make([]string, len(items)) |
| 185 | receipts := make([]string, len(items)) |
| 186 | receiptBytes := 0 |
| 187 | for i, item := range items { |
| 188 | prose[i], receipts[i] = splitHostReceipts(item.answer) |
| 189 | receiptBytes += len(receipts[i]) + 1 |
| 190 | } |
| 191 | if reserve := subagentAggregateBudgetBytes / 2; receiptBytes > reserve && len(items) > 0 { |
| 192 | receiptBytes = 0 |
| 193 | for i := range receipts { |
| 194 | receipts[i] = boundedHostReceipts(receipts[i], reserve/len(items)) |
| 195 | receiptBytes += len(receipts[i]) + 1 |
| 196 | } |
| 197 | } |
| 198 | |
| 199 | baseBytes := len(prefix) + receiptBytes |
| 200 | completed := 0 |
| 201 | for i, item := range items { |
| 202 | baseBytes += len(item.header) + len(item.status) + len(item.detail) |
| 203 | if item.ref != "" { |
| 204 | baseBytes += len("Subagent reference: \n") + len(item.ref) |
| 205 | } |
| 206 | if prose[i] != "" { |
| 207 | baseBytes += len("Final answer preview:\n\n") |
| 208 | completed++ |
| 209 | } |
| 210 | } |
| 211 | available := max(subagentAggregateBudgetBytes-baseBytes, 0) |
| 212 | perAnswer := 0 |
| 213 | if completed > 0 { |
| 214 | perAnswer = available / completed |
| 215 | } |
| 216 | |
| 217 | var b strings.Builder |
| 218 | b.Grow(minInt(subagentAggregateBudgetBytes, baseBytes+available)) |
| 219 | b.WriteString(prefix) |
| 220 | for i, item := range items { |
| 221 | b.WriteString(item.header) |
| 222 | b.WriteString(item.status) |
| 223 | if item.ref != "" { |
| 224 | fmt.Fprintf(&b, "Subagent reference: %s\n", item.ref) |
| 225 | } |
| 226 | if item.detail != "" { |
| 227 | b.WriteString(item.detail) |
| 228 | } |
| 229 | if prose[i] != "" { |
| 230 | b.WriteString("Final answer preview:\n") |
| 231 | b.WriteString(subagentAnswerPreview(prose[i], item.ref, perAnswer)) |
| 232 | b.WriteByte('\n') |
| 233 | } |
| 234 | if receipts[i] != "" { |
| 235 | b.WriteString(receipts[i]) |
| 236 | b.WriteByte('\n') |
| 237 | } |
| 238 | } |
| 239 | return b.String() |
| 240 | } |
| 241 | |
| 242 | func subagentAnswerPreview(answer, ref string, limit int) string { |
| 243 | answer = strings.TrimSpace(answer) |
| 244 | if len(answer) <= limit { |
| 245 | return answer |
| 246 | } |
| 247 | if limit <= 0 { |
| 248 | return "" |
| 249 | } |
| 250 | marker := "\n…[preview truncated; full result unavailable in this ephemeral run]…\n" |
| 251 | if ref != "" { |
| 252 | marker = fmt.Sprintf("\n…[preview truncated; read the full result with read_subagent_result(ref=%q)]…\n", ref) |
| 253 | } |
| 254 | if len(marker) >= limit { |
| 255 | return utf8Prefix(answer, limit) |
| 256 | } |
| 257 | keep := limit - len(marker) |
| 258 | headBytes := keep / 2 |
| 259 | tailBytes := keep - headBytes |
| 260 | head := utf8Prefix(answer, headBytes) |
| 261 | tail := utf8Suffix(answer, tailBytes) |
| 262 | return head + marker + tail |
| 263 | } |
| 264 | |
| 265 | func utf8Prefix(s string, limit int) string { |
| 266 | if limit >= len(s) { |
| 267 | return s |
| 268 | } |
| 269 | if limit <= 0 { |
| 270 | return "" |
| 271 | } |
| 272 | for limit > 0 && !utf8.RuneStart(s[limit]) { |
| 273 | limit-- |
| 274 | } |
| 275 | return s[:limit] |
| 276 | } |
| 277 | |
| 278 | func utf8Suffix(s string, limit int) string { |
| 279 | if limit >= len(s) { |
| 280 | return s |
| 281 | } |
| 282 | if limit <= 0 { |
| 283 | return "" |
| 284 | } |
| 285 | start := len(s) - limit |
| 286 | for start < len(s) && !utf8.RuneStart(s[start]) { |
| 287 | start++ |
| 288 | } |
| 289 | return s[start:] |
| 290 | } |
| 291 | |
| 292 | func boundedInline(s string, limit int) string { |
| 293 | s = strings.Join(strings.Fields(s), " ") |
| 294 | if len(s) <= limit { |
| 295 | return s |
| 296 | } |
| 297 | if limit <= len("…") { |
| 298 | return utf8Prefix(s, limit) |
| 299 | } |
| 300 | return utf8Prefix(s, limit-len("…")) + "…" |
| 301 | } |
| 302 | |
| 303 | func splitSubagentRunResult(output string) (answer, ref string) { |
| 304 | ref = extractSubagentRef(output) |
| 305 | if ref == "" { |
| 306 | return strings.TrimSpace(output), "" |
| 307 | } |
| 308 | const marker = "\n\nFinal answer:\n" |
| 309 | if _, after, ok := strings.Cut(output, marker); ok { |
| 310 | return strings.TrimSpace(after), ref |
| 311 | } |
| 312 | return strings.TrimSpace(output), ref |
| 313 | } |
| 314 | |
| 315 | func extractSubagentRef(output string) string { |
| 316 | const prefix = "Subagent reference: " |
| 317 | if !strings.HasPrefix(output, prefix) { |
| 318 | return "" |
| 319 | } |
| 320 | line := output |
| 321 | if end := strings.IndexByte(line, '\n'); end >= 0 { |
| 322 | line = line[:end] |
| 323 | } |
| 324 | ref := strings.TrimSpace(strings.TrimPrefix(line, prefix)) |
| 325 | if validSubagentRef(ref) { |
| 326 | return ref |
| 327 | } |
| 328 | return "" |
| 329 | } |
| 330 |