| 1 | package guardian |
| 2 | |
| 3 | import ( |
| 4 | "fmt" |
| 5 | "slices" |
| 6 | "strings" |
| 7 | "unicode/utf8" |
| 8 | |
| 9 | "reasonix/internal/provider" |
| 10 | ) |
| 11 | |
| 12 | // TranscriptEntry is one simplified conversation entry for guardian review. |
| 13 | type TranscriptEntry struct { |
| 14 | Kind string // "user" | "assistant" | "tool" |
| 15 | Text string |
| 16 | } |
| 17 | |
| 18 | // TranscriptCursor remembers which transcript entries have already been sent to |
| 19 | // the guardian session so subsequent reviews can send only the delta. |
| 20 | type TranscriptCursor struct { |
| 21 | HistoryVersion int // agent session RewriteVersion at cursor time |
| 22 | EntryCount int // how many entries have already been sent |
| 23 | } |
| 24 | |
| 25 | const ( |
| 26 | maxMessageEntryTokens = 2000 // per-entry cap for user/assistant |
| 27 | maxToolEntryTokens = 1000 // per-entry cap for tool call/result |
| 28 | maxMessageTranscript = 10000 // total token budget for user/assistant entries |
| 29 | maxToolTranscript = 10000 // total token budget for tool entries |
| 30 | maxRecentEntries = 40 // max non-user entries from the tail |
| 31 | ) |
| 32 | |
| 33 | // ExtractTranscript builds a compact transcript from the agent session messages |
| 34 | // suitable for guardian review. Returns entries in chronological order. |
| 35 | func ExtractTranscript(msgs []provider.Message) []TranscriptEntry { |
| 36 | var entries []TranscriptEntry |
| 37 | for _, m := range msgs { |
| 38 | switch m.Role { |
| 39 | case provider.RoleSystem: |
| 40 | // skip — guardian gets its own system prompt |
| 41 | continue |
| 42 | case provider.RoleUser: |
| 43 | if text := strings.TrimSpace(m.Content); text != "" { |
| 44 | entries = append(entries, TranscriptEntry{Kind: "user", Text: text}) |
| 45 | } |
| 46 | case provider.RoleAssistant: |
| 47 | text := m.Content |
| 48 | if text == "" && len(m.ToolCalls) > 0 { |
| 49 | // assistant turn that only issued tool calls — include as "tool_calls" |
| 50 | for _, tc := range m.ToolCalls { |
| 51 | entries = append(entries, TranscriptEntry{ |
| 52 | Kind: "tool", |
| 53 | Text: fmt.Sprintf("tool %s call: %s", tc.Name, firstRunesStr(tc.Arguments, 500)), |
| 54 | }) |
| 55 | } |
| 56 | continue |
| 57 | } |
| 58 | text = strings.TrimSpace(text) |
| 59 | if text == "" { |
| 60 | continue |
| 61 | } |
| 62 | entries = append(entries, TranscriptEntry{Kind: "assistant", Text: text}) |
| 63 | case provider.RoleTool: |
| 64 | text := strings.TrimSpace(m.Content) |
| 65 | if text == "" { |
| 66 | continue |
| 67 | } |
| 68 | label := fmt.Sprintf("tool %s result", m.Name) |
| 69 | entries = append(entries, TranscriptEntry{Kind: "tool", Text: label + ": " + text}) |
| 70 | } |
| 71 | } |
| 72 | return entries |
| 73 | } |
| 74 | |
| 75 | // renderTranscript selects and formats entries for guardian prompt inclusion. |
| 76 | // Returns the rendered transcript lines and an omission-note (non-empty when some |
| 77 | // entries were dropped due to budget constraints). |
| 78 | func renderTranscript(entries []TranscriptEntry) ([]string, string) { |
| 79 | if len(entries) == 0 { |
| 80 | return []string{"<no retained transcript entries>"}, "" |
| 81 | } |
| 82 | |
| 83 | // Pre-compute rendered text and estimated token counts for every entry. |
| 84 | type rendered struct { |
| 85 | text string |
| 86 | index int |
| 87 | toks int |
| 88 | } |
| 89 | var all []rendered |
| 90 | for i, e := range entries { |
| 91 | tokCap := maxMessageEntryTokens |
| 92 | if e.Kind == "tool" { |
| 93 | tokCap = maxToolEntryTokens |
| 94 | } |
| 95 | text, _ := truncateText(e.Text, tokCap) |
| 96 | line := fmt.Sprintf("[%d] %s: %s", i+1, e.Kind, text) |
| 97 | toks := estimateTokens(line) |
| 98 | all = append(all, rendered{text: line, index: i, toks: toks}) |
| 99 | } |
| 100 | |
| 101 | // Select entries with user-anchored, tool-separated budgets. |
| 102 | included := make([]bool, len(entries)) |
| 103 | msgToks := 0 |
| 104 | toolToks := 0 |
| 105 | |
| 106 | // Find user entry indices. |
| 107 | var userIdx []int |
| 108 | for i, e := range entries { |
| 109 | if e.Kind == "user" { |
| 110 | userIdx = append(userIdx, i) |
| 111 | } |
| 112 | } |
| 113 | |
| 114 | // Always keep the first user entry (anchor). |
| 115 | if len(userIdx) > 0 && userIdx[0] < len(all) { |
| 116 | first := userIdx[0] |
| 117 | included[first] = true |
| 118 | msgToks += all[first].toks |
| 119 | } |
| 120 | |
| 121 | // Always keep the last user entry (anchor), if different. |
| 122 | if len(userIdx) > 1 && userIdx[len(userIdx)-1] != userIdx[0] { |
| 123 | last := userIdx[len(userIdx)-1] |
| 124 | if last < len(all) && !included[last] && msgToks+all[last].toks <= maxMessageTranscript { |
| 125 | included[last] = true |
| 126 | msgToks += all[last].toks |
| 127 | } |
| 128 | } |
| 129 | |
| 130 | // Fill remaining message budget with user entries from newest to oldest. |
| 131 | for _, v := range slices.Backward(userIdx) { |
| 132 | idx := v |
| 133 | if idx >= len(all) || included[idx] { |
| 134 | continue |
| 135 | } |
| 136 | if msgToks+all[idx].toks > maxMessageTranscript { |
| 137 | continue |
| 138 | } |
| 139 | included[idx] = true |
| 140 | msgToks += all[idx].toks |
| 141 | } |
| 142 | |
| 143 | // Add recent non-user entries from newest to oldest. |
| 144 | recent := 0 |
| 145 | for i := len(entries) - 1; i >= 0 && recent < maxRecentEntries; i-- { |
| 146 | if included[i] || entries[i].Kind == "user" { |
| 147 | continue |
| 148 | } |
| 149 | add := all[i].toks |
| 150 | if entries[i].Kind == "tool" { |
| 151 | if toolToks+add > maxToolTranscript { |
| 152 | continue |
| 153 | } |
| 154 | toolToks += add |
| 155 | } else { |
| 156 | if msgToks+add > maxMessageTranscript { |
| 157 | continue |
| 158 | } |
| 159 | msgToks += add |
| 160 | } |
| 161 | included[i] = true |
| 162 | recent++ |
| 163 | } |
| 164 | |
| 165 | // Build the result. |
| 166 | var lines []string |
| 167 | for i, r := range all { |
| 168 | if included[i] { |
| 169 | lines = append(lines, r.text) |
| 170 | } |
| 171 | } |
| 172 | omitted := false |
| 173 | for _, b := range included { |
| 174 | if !b { |
| 175 | omitted = true |
| 176 | break |
| 177 | } |
| 178 | } |
| 179 | if omitted { |
| 180 | return lines, "Some conversation entries were omitted." |
| 181 | } |
| 182 | return lines, "" |
| 183 | } |
| 184 | |
| 185 | // FormatTranscript returns a complete guardian transcript prompt block. |
| 186 | func FormatTranscript(entries []TranscriptEntry) string { |
| 187 | lines, omission := renderTranscript(entries) |
| 188 | var b strings.Builder |
| 189 | b.WriteString(">>> TRANSCRIPT START\n") |
| 190 | for _, line := range lines { |
| 191 | b.WriteString(line) |
| 192 | b.WriteByte('\n') |
| 193 | } |
| 194 | b.WriteString(">>> TRANSCRIPT END\n") |
| 195 | if omission != "" { |
| 196 | b.WriteByte('\n') |
| 197 | b.WriteString(omission) |
| 198 | b.WriteByte('\n') |
| 199 | } |
| 200 | return b.String() |
| 201 | } |
| 202 | |
| 203 | // truncateText trims text to roughly tokCap tokens, keeping head and tail. |
| 204 | // Returns the truncated text and whether truncation occurred. |
| 205 | func truncateText(content string, tokCap int) (string, bool) { |
| 206 | if content == "" { |
| 207 | return content, false |
| 208 | } |
| 209 | est := estimateTokens(content) |
| 210 | if est <= tokCap { |
| 211 | return content, false |
| 212 | } |
| 213 | // Simple truncation: keep head + tail with marker. |
| 214 | maxBytes := tokCap * 4 // rough byte estimate |
| 215 | if len(content) <= maxBytes { |
| 216 | return content, false |
| 217 | } |
| 218 | marker := "<truncated>" |
| 219 | avail := maxBytes - len(marker) |
| 220 | if avail <= 0 { |
| 221 | return marker, true |
| 222 | } |
| 223 | head := avail / 2 |
| 224 | tail := avail - head |
| 225 | |
| 226 | // Convert to runes for safe boundary alignment. |
| 227 | runes := []rune(content) |
| 228 | // Estimate how many runes fit in head/tail bytes (conservative: assume |
| 229 | // max 4 bytes per rune). |
| 230 | headRunes := min(head/4, len(runes)) |
| 231 | tailRunes := max(min(tail/4, len(runes)-headRunes), 0) |
| 232 | return string(runes[:headRunes]) + marker + string(runes[len(runes)-tailRunes:]), true |
| 233 | } |
| 234 | |
| 235 | // estimateTokens gives a rough token count for display purposes (not API-accurate). |
| 236 | func estimateTokens(s string) int { |
| 237 | bytes := len(s) |
| 238 | runes := utf8.RuneCountInString(s) |
| 239 | byBytes := (bytes + 3) / 4 // ~4 chars per token for English |
| 240 | if runes > byBytes { |
| 241 | return runes |
| 242 | } |
| 243 | return byBytes |
| 244 | } |
| 245 |