--- /dev/null
+package main
+
+import (
+ "context"
+ "errors"
+ "fmt"
+ "strings"
+ "unicode/utf8"
+)
+
+// compactionTries is the most calls for one node.
+const compactionTries = 5
+
+// ruler shows the model the size limit of a line. Models cannot count bytes,
+// and a sample line as the ruler gets its content copied.
+var ruler = strings.Repeat("-", nodeBytes)
+
+// Compactor builds the nodes of one agent with a model. A compaction is a call
+// like a turn, with the same system prompt and tools, so it reads them from the
+// prompt cache of the turns. The tools are never called. After them comes one
+// user message with the compaction view up to the node and the task.
+//
+// When the line is over nodeBytes, the next try sends the same view and task,
+// plus a note with the size of the newest line and its cut at the limit. A try
+// never sends the model's earlier reply or reasoning back, so every try has the
+// same cached prefix and about the same size. After at most compactionTries
+// tries, the shortest line is the node. A few bytes over the limit is fine,
+// because the view measures the real sizes. A call that fails before any line
+// fails the build, and the core tries it again at the next message.
+type Compactor struct {
+ client *Client
+ model ModelConfig
+ instructions string
+ tools []Tool
+}
+
+// newCompactor returns the compactor of the agent name, which sends its calls
+// through client with model.
+func newCompactor(client *Client, name string, model ModelConfig) *Compactor {
+ return &Compactor{
+ client: client,
+ model: model,
+ instructions: prompt(name),
+ tools: agentTools(),
+ }
+}
+
+// Summarize returns the line of the node of task.
+func (c *Compactor) Summarize(ctx context.Context, task Task) (string, error) {
+ view := task.Context + "\n"
+ text, err := compactionTask(task)
+ if err != nil {
+ return "", err
+ }
+
+ var lines []string
+ note := ""
+ for len(lines) < compactionTries {
+ parts := []string{view, text}
+ if note != "" {
+ parts = append(parts, note)
+ }
+
+ var response Response
+ response, err = c.client.Create(ctx, Request{
+ Model: c.model.Model,
+ Effort: c.model.Effort,
+ Instructions: c.instructions,
+ Tools: c.tools,
+ Input: []any{userMessage(parts...)},
+ })
+ if err != nil {
+ break
+ }
+
+ line := strings.TrimSpace(response.Text)
+ if line == "" {
+ err = errors.New("compaction gave no line")
+ break
+ }
+
+ lines = append(lines, line)
+ if len(line) <= nodeBytes {
+ break
+ }
+
+ note = tooLong(line)
+ }
+
+ if len(lines) == 0 {
+ return "", fmt.Errorf("compact node (%d, %d): %w", task.Level, task.Index, err)
+ }
+
+ return shortest(lines), nil
+}
+
+// compactionTask returns the task of a build, with its input.
+func compactionTask(task Task) (string, error) {
+ if task.Level == 0 && len(task.Input) == 1 {
+ return fmt.Sprintf(`Compaction: compress message %d into one line of at most %d bytes
+(about 70 words), the length of this ruler:
+%s
+<input>
+%s
+</input>`, task.Index, nodeBytes, ruler, task.Input[0]), nil
+ }
+
+ if task.Level > 0 && len(task.Input) == 2 {
+ first := task.Index << task.Level
+ half := 1 << (task.Level - 1)
+
+ return fmt.Sprintf(`Compaction: merge lines %d+%d and %d+%d, adjacent, into one line of at most
+%d bytes (about 70 words), the length of this ruler:
+%s
+<chat> may hold their messages, %d to %d, in more detail: take details
+of them from there too.
+<input>
+%s
+%s
+</input>`, first, half, first+half, half, nodeBytes, ruler, first, nodeEnd(task.Level, task.Index)-1, task.Input[0], task.Input[1]), nil
+ }
+
+ return "", fmt.Errorf("node (%d, %d) has %d inputs", task.Level, task.Index, len(task.Input))
+}
+
+// tooLong returns the note for a line over nodeBytes: its size and its first
+// nodeBytes bytes, which show the model where the limit cuts it.
+func tooLong(line string) string {
+ return fmt.Sprintf(`Too long: your last line for this <input> was %d bytes,
+over the %d-byte limit. Write the whole line again, cutting just
+enough of the least valuable items to fit before this cut:
+%s| ← LIMIT`, len(line), nodeBytes, cutLine(line))
+}
+
+// cutLine returns the first nodeBytes bytes of line, without a part of a
+// character at the end.
+func cutLine(line string) string {
+ if len(line) <= nodeBytes {
+ return line
+ }
+
+ cut := line[:nodeBytes]
+ for !utf8.ValidString(cut) {
+ cut = cut[:len(cut)-1]
+ }
+
+ return cut
+}
+
+// shortest returns the first of the shortest lines.
+func shortest(lines []string) string {
+ best := lines[0]
+ for _, line := range lines[1:] {
+ if len(line) < len(best) {
+ best = line
+ }
+ }
+
+ return best
+}
--- /dev/null
+package main
+
+import (
+ "encoding/json"
+ "io"
+ "net/http"
+ "path/filepath"
+ "strconv"
+ "strings"
+ "testing"
+ "unicode/utf8"
+
+ "github.com/stretchr/testify/require"
+)
+
+func TestCompactorSendsThePromptToolsAndTask(t *testing.T) {
+ server := newFakeResponses(t)
+ compactor := newTestCompactor(t, server)
+
+ line, err := compactor.Summarize(t.Context(), Task{
+ Level: 0,
+ Index: 7,
+ Context: "<chat>\n0+4|user: earlier\n</chat>",
+ Input: []string{"user: " + strings.Repeat("x", 600)},
+ })
+ require.NoError(t, err)
+ require.Equal(t, "a line", line)
+ require.Equal(t, 1, server.Calls())
+
+ body := server.Call(0).body
+ require.Equal(t, prompt("Ada"), body["instructions"])
+ require.Equal(t, "gpt-test", body["model"])
+ require.Equal(t, map[string]any{"effort": "high"}, body["reasoning"])
+ require.Equal(t, "agent-key", body["prompt_cache_key"])
+
+ tools, err := json.Marshal(agentTools())
+ require.NoError(t, err)
+
+ sent, err := json.Marshal(body["tools"])
+ require.NoError(t, err)
+ require.JSONEq(t, string(tools), string(sent))
+
+ parts := inputParts(t, server.Call(0))
+ require.Equal(t, []string{
+ "<chat>\n0+4|user: earlier\n</chat>\n",
+ "Compaction: compress message 7 into one line of at most 512 bytes\n" +
+ "(about 70 words), the length of this ruler:\n" +
+ strings.Repeat("-", 512) + "\n" +
+ "<input>\nuser: " + strings.Repeat("x", 600) + "\n</input>",
+ }, parts)
+}
+
+func TestCompactorWritesTheMergeTask(t *testing.T) {
+ text, err := compactionTask(Task{
+ Level: 2,
+ Index: 3,
+ Input: []string{"left line", "right line"},
+ })
+ require.NoError(t, err)
+ require.Equal(t, "Compaction: merge lines 12+2 and 14+2, adjacent, into one line of at most\n"+
+ "512 bytes (about 70 words), the length of this ruler:\n"+
+ strings.Repeat("-", 512)+"\n"+
+ "<chat> may hold their messages, 12 to 15, in more detail: take details\n"+
+ "of them from there too.\n"+
+ "<input>\nleft line\nright line\n</input>", text)
+}
+
+func TestCompactorRetriesALongLineWithTheNewestNote(t *testing.T) {
+ long := []string{strings.Repeat("a", 600), strings.Repeat("b", 550), strings.Repeat("c", 400)}
+ server := newFakeResponses(t)
+ server.reply = func(w http.ResponseWriter, call fakeCall) {
+ writeEvents(w, completedEvent([]any{messageItem(long[call.number])}, 100, 0, 5))
+ }
+
+ line, err := newTestCompactor(t, server).Summarize(t.Context(), leafTask())
+ require.NoError(t, err)
+ require.Equal(t, long[2], line)
+ require.Equal(t, 3, server.Calls())
+
+ first := inputParts(t, server.Call(0))
+ require.Len(t, first, 2)
+ for n, want := range []string{long[0], long[1]} {
+ call := server.Call(n + 1)
+ parts := inputParts(t, call)
+ require.Equal(t, first, parts[:2])
+ require.Equal(t, []string{tooLong(want)}, parts[2:])
+ require.Contains(t, parts[2], "was "+strconv.Itoa(len(want))+" bytes,")
+ require.Contains(t, parts[2], "\n"+want[:512]+"| ← LIMIT")
+
+ note, err := json.Marshal(map[string]string{
+ "type": "input_text",
+ "text": parts[2],
+ })
+ require.NoError(t, err)
+ require.LessOrEqual(t, len(call.raw), len(server.Call(0).raw)+len(",")+len(note))
+ }
+}
+
+func TestCompactorKeepsTheShortestOfFiveLines(t *testing.T) {
+ sizes := []int{700, 530, 600, 520, 560, 513}
+ server := newFakeResponses(t)
+ server.reply = func(w http.ResponseWriter, call fakeCall) {
+ writeEvents(w, completedEvent([]any{messageItem(strings.Repeat("z", sizes[call.number]))}, 100, 0, 5))
+ }
+
+ line, err := newTestCompactor(t, server).Summarize(t.Context(), leafTask())
+ require.NoError(t, err)
+ require.Equal(t, compactionTries, server.Calls())
+ require.Len(t, line, 520)
+}
+
+func TestCompactorFailsWithoutALine(t *testing.T) {
+ testCases := []struct {
+ name string
+ reply func(http.ResponseWriter, fakeCall)
+ want string
+ }{
+ {
+ name: "failed call",
+ reply: func(w http.ResponseWriter, call fakeCall) {
+ w.WriteHeader(http.StatusInternalServerError)
+ _, _ = io.WriteString(w, "down")
+ },
+ want: "HTTP 500",
+ },
+ {
+ name: "tool call and no text",
+ reply: func(w http.ResponseWriter, call fakeCall) {
+ writeEvents(w, completedEvent([]any{map[string]any{"type": "function_call", "name": "zoom", "arguments": "{}"}}, 100, 0, 5))
+ },
+ want: "no line",
+ },
+ }
+
+ for _, tc := range testCases {
+ t.Run(tc.name, func(t *testing.T) {
+ server := newFakeResponses(t)
+ server.reply = tc.reply
+
+ _, err := newTestCompactor(t, server).Summarize(t.Context(), leafTask())
+ require.ErrorContains(t, err, tc.want)
+ require.Equal(t, 1, server.Calls())
+ })
+ }
+}
+
+func TestCutLineKeepsWholeCharacters(t *testing.T) {
+ line := strings.Repeat("a", 511) + "é" + "tail"
+ cut := cutLine(line)
+ require.Equal(t, strings.Repeat("a", 511), cut)
+ require.True(t, utf8.ValidString(cut))
+ require.Equal(t, "short", cutLine("short"))
+}
+
+func TestCompactorBuildsNodesInTheCore(t *testing.T) {
+ server := newFakeResponses(t)
+ server.reply = func(w http.ResponseWriter, call fakeCall) {
+ if call.number == 0 {
+ w.WriteHeader(http.StatusServiceUnavailable)
+ return
+ }
+
+ writeEvents(w, completedEvent([]any{messageItem("summary of the long output")}, 100, 0, 5))
+ }
+
+ memory, err := openMemory(t.Context(), t.TempDir(), newTestClock().Now, newTestCompactor(t, server))
+ require.NoError(t, err)
+
+ defer func() {
+ require.NoError(t, memory.Close())
+ }()
+
+ _, err = memory.Append("echo", strings.Repeat("output ", 200))
+ require.NoError(t, err)
+ require.NoError(t, memory.Wait(t.Context()))
+ require.False(t, isBuilt(t, memory.tree, 0, 0))
+
+ _, err = memory.Append("user", "next")
+ require.NoError(t, err)
+ require.NoError(t, memory.Wait(t.Context()))
+
+ node := readNode(t, memory.tree, 0, 0)
+ require.Equal(t, "summary of the long output", node.Text)
+ require.Equal(t, "<chat>\n0+1|summary of the long output\n1+1|user: next\n</chat>", memory.View())
+ require.Equal(t, 2, server.Calls())
+}
+
+func newTestCompactor(t *testing.T, server *fakeResponses) *Compactor {
+ t.Helper()
+
+ client := newClient(server.URL, apiKey(testKey), "agent-key", filepath.Join(t.TempDir(), "usage.jsonl"))
+
+ return newCompactor(client, "Ada", ModelConfig{
+ Model: "gpt-test",
+ Effort: "high",
+ })
+}
+
+func leafTask() Task {
+ return Task{
+ Level: 0,
+ Index: 0,
+ Context: "<chat>\n</chat>",
+ Input: []string{"user: " + strings.Repeat("y", 600)},
+ }
+}
+
+// inputParts returns the texts of the one user message of call.
+func inputParts(t *testing.T, call fakeCall) []string {
+ t.Helper()
+
+ var body struct {
+ Input []struct {
+ Role string `json:"role"`
+ Content []struct {
+ Type string `json:"type"`
+ Text string `json:"text"`
+ } `json:"content"`
+ } `json:"input"`
+ }
+
+ require.NoError(t, json.Unmarshal(call.raw, &body))
+ require.Len(t, body.Input, 1)
+ require.Equal(t, "user", body.Input[0].Role)
+
+ texts := make([]string, len(body.Input[0].Content))
+ for n, part := range body.Input[0].Content {
+ require.Equal(t, "input_text", part.Type)
+ texts[n] = part.Text
+ }
+
+ return texts
+}
projects / onechat / commitdiff