fix(delegate-task): add token counting and truncation to prevent context overflow

Fixes #1815, #1733
2026-02-25 14:03:47 +09:00
parent 15519b9580
commit fc1b6e4917
8 changed files with 296 additions and 23 deletions
@@ -0,0 +1,121 @@
+declare const require: (name: string) => unknown
+const { describe, test, expect } = require("bun:test") as {
+  describe: (name: string, fn: () => void) => void
+  test: (name: string, fn: () => void) => void
+  expect: (value: unknown) => {
+    toBe: (expected: unknown) => void
+    toContain: (expected: string) => void
+    not: {
+      toContain: (expected: string) => void
+    }
+    toBeLessThanOrEqual: (expected: number) => void
+    toBeUndefined: () => void
+  }
+}
+
+import {
+  buildSystemContentWithTokenLimit,
+  estimateTokenCount,
+  truncateToTokenBudget,
+} from "./token-limiter"
+
+describe("token-limiter", () => {
+  test("estimateTokenCount uses 1 token per 4 chars approximation", () => {
+    // given
+    const text = "12345678"
+
+    // when
+    const result = estimateTokenCount(text)
+
+    // then
+    expect(result).toBe(2)
+  })
+
+  test("truncateToTokenBudget keeps text within requested token budget", () => {
+    // given
+    const content = "A".repeat(120)
+    const maxTokens = 10
+
+    // when
+    const result = truncateToTokenBudget(content, maxTokens)
+
+    // then
+    expect(estimateTokenCount(result)).toBeLessThanOrEqual(maxTokens)
+  })
+
+  test("buildSystemContentWithTokenLimit returns undefined when there is no content", () => {
+    // given
+    const input = {
+      skillContent: undefined,
+      skillContents: [],
+      categoryPromptAppend: undefined,
+      agentsContext: undefined,
+      planAgentPrepend: "",
+    }
+
+    // when
+    const result = buildSystemContentWithTokenLimit(input, 20)
+
+    // then
+    expect(result).toBeUndefined()
+  })
+
+  test("buildSystemContentWithTokenLimit truncates skills before category and agents context", () => {
+    // given
+    const input = {
+      skillContents: [
+        "SKILL_ALPHA:" + "a".repeat(180),
+        "SKILL_BETA:" + "b".repeat(180),
+      ],
+      categoryPromptAppend: "CATEGORY_APPEND:keep",
+      agentsContext: "AGENTS_CONTEXT:keep",
+      planAgentPrepend: "",
+    }
+
+    // when
+    const result = buildSystemContentWithTokenLimit(input, 80)
+
+    // then
+    expect(result).toContain("AGENTS_CONTEXT:keep")
+    expect(result).toContain("CATEGORY_APPEND:keep")
+    expect(result).toContain("SKILL_ALPHA:")
+    expect(estimateTokenCount(result as string)).toBeLessThanOrEqual(80)
+  })
+
+  test("buildSystemContentWithTokenLimit truncates category after skills are exhausted", () => {
+    // given
+    const input = {
+      skillContents: ["SKILL_ALPHA:" + "a".repeat(220)],
+      categoryPromptAppend: "CATEGORY_APPEND:" + "c".repeat(220),
+      agentsContext: "AGENTS_CONTEXT:keep",
+      planAgentPrepend: "",
+    }
+
+    // when
+    const result = buildSystemContentWithTokenLimit(input, 30)
+
+    // then
+    expect(result).toContain("AGENTS_CONTEXT:keep")
+    expect(result).not.toContain("SKILL_ALPHA:" + "a".repeat(80))
+    expect(estimateTokenCount(result as string)).toBeLessThanOrEqual(30)
+  })
+
+  test("buildSystemContentWithTokenLimit truncates agents context last", () => {
+    // given
+    const input = {
+      skillContents: ["SKILL_ALPHA:" + "a".repeat(220)],
+      categoryPromptAppend: "CATEGORY_APPEND:" + "c".repeat(220),
+      agentsContext: "AGENTS_CONTEXT:" + "g".repeat(220),
+      planAgentPrepend: "",
+    }
+
+    // when
+    const result = buildSystemContentWithTokenLimit(input, 10)
+
+    // then
+    expect(result).toContain("AGENTS_CONTEXT:")
+    expect(result).not.toContain("SKILL_ALPHA:")
+    expect(result).not.toContain("CATEGORY_APPEND:")
+    expect(estimateTokenCount(result as string)).toBeLessThanOrEqual(10)
+  })
+})