fix(memory): add config-memory prompt block to prevent SDK auto-include truncation (#90)

Mirror the working-memory.ts truncation pattern for phantom-config/memory/
files (heartbeat-log.md, presence-log.md, corrections.md, principles.md).
Each file is capped at 100 lines with header + recent tail + compaction
nudge, preventing the SDK from silently replacing large memory files with
stubs at session start.

Excludes agent-notes.md to preserve the existing architecture decision
(agent reads its own writes via Read tool to avoid feedback loop).

10 new tests, all 1839 project tests pass.

Author: kagura-agent

src/agent/prompt-assembler.ts

@@ -2,8 +2,10 @@ import { existsSync } from "node:fs";
 import { join } from "node:path";
 import type { PhantomConfig } from "../config/types.ts";
 import type { EvolvedConfig } from "../evolution/types.ts";
+import { getPhantomConfigMemoryRoot } from "../memory-files/paths.ts";
 import type { RoleTemplate } from "../roles/types.ts";
 import { buildAgentMemoryInstructions } from "./prompt-blocks/agent-memory-instructions.ts";
+import { buildConfigMemory } from "./prompt-blocks/config-memory.ts";
 import { buildDashboardAwarenessLines } from "./prompt-blocks/dashboard-awareness.ts";
 import { buildEvolvedSections } from "./prompt-blocks/evolved.ts";
 import { buildInstructions } from "./prompt-blocks/instructions.ts";
@@ -69,6 +71,12 @@ export function assemblePrompt(
 		sections.push(workingMemory);
 	}
 
+	// 8.5. Config memory - phantom-config/memory/ files (agent-notes.md, corrections.md, etc.)
+	const configMemory = buildConfigMemory(getPhantomConfigMemoryRoot());
+	if (configMemory) {
+		sections.push(configMemory);
+	}
+
 	// 9. Memory context - what you remember (dynamic, changes per query)
 	if (memoryContext) {
 		sections.push(buildMemorySection(memoryContext));

src/agent/prompt-blocks/__tests__/config-memory.test.ts

@@ -0,0 +1,140 @@
+import { afterEach, beforeEach, describe, expect, test } from "bun:test";
+import { existsSync, mkdirSync, rmSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { buildConfigMemory } from "../config-memory.ts";
+
+describe("buildConfigMemory", () => {
+	const testDir = join(process.cwd(), "test-config-memory");
+
+	beforeEach(() => {
+		if (existsSync(testDir)) {
+			rmSync(testDir, { recursive: true, force: true });
+		}
+		mkdirSync(testDir, { recursive: true });
+	});
+
+	afterEach(() => {
+		if (existsSync(testDir)) {
+			rmSync(testDir, { recursive: true, force: true });
+		}
+	});
+
+	test("returns empty string when directory does not exist", () => {
+		const nonExistentDir = join(testDir, "does-not-exist");
+		const result = buildConfigMemory(nonExistentDir);
+		expect(result).toBe("");
+	});
+
+	test("returns empty string when directory exists but has no known files", () => {
+		const result = buildConfigMemory(testDir);
+		expect(result).toBe("");
+	});
+
+	test("returns empty string when files exist but are empty", () => {
+		writeFileSync(join(testDir, "agent-notes.md"), "");
+		writeFileSync(join(testDir, "corrections.md"), "");
+		const result = buildConfigMemory(testDir);
+		expect(result).toBe("");
+	});
+
+	test("returns file content with heading when file is under MAX_LINES", () => {
+		const content = "# Test Notes\n\nThis is a short note.\nAnother line.";
+		writeFileSync(join(testDir, "corrections.md"), content);
+
+		const result = buildConfigMemory(testDir);
+
+		expect(result).toContain("# Config Memory Files");
+		expect(result).toContain("## corrections.md");
+		expect(result).toContain("This is a short note.");
+		expect(result).toContain("Another line.");
+		expect(result).not.toContain("was truncated");
+	});
+
+	test("truncates file when over MAX_LINES with header + tail + compaction nudge", () => {
+		const lines = ["# Header Line 1", "## Header Line 2", "### Header Line 3"];
+		for (let i = 4; i <= 150; i++) {
+			lines.push(`Line ${i}`);
+		}
+		const content = lines.join("\n");
+		writeFileSync(join(testDir, "corrections.md"), content);
+
+		const result = buildConfigMemory(testDir);
+
+		expect(result).toContain("# Config Memory Files");
+		expect(result).toContain("## corrections.md");
+		expect(result).toContain("# Header Line 1");
+		expect(result).toContain("## Header Line 2");
+		expect(result).toContain("### Header Line 3");
+		expect(result).toContain("<!-- corrections.md was truncated. Please compact this file. -->");
+		expect(result).toContain("Line 150");
+		// Middle lines should be omitted
+		expect(result).not.toContain("Line 50");
+	});
+
+	test("processes multiple files independently", () => {
+		writeFileSync(join(testDir, "corrections.md"), "# Corrections\n\nCorrection 1");
+		writeFileSync(join(testDir, "principles.md"), "# Principles\n\nPrinciple 1");
+
+		const result = buildConfigMemory(testDir);
+
+		expect(result).toContain("## corrections.md");
+		expect(result).toContain("Correction 1");
+		expect(result).toContain("## principles.md");
+		expect(result).toContain("Principle 1");
+	});
+
+	test("only reads known memory files, not arbitrary files", () => {
+		writeFileSync(join(testDir, "corrections.md"), "# Known File\n\nThis should appear.");
+		writeFileSync(join(testDir, "unknown-file.md"), "# Unknown File\n\nThis should NOT appear.");
+
+		const result = buildConfigMemory(testDir);
+
+		expect(result).toContain("corrections.md");
+		expect(result).toContain("This should appear.");
+		expect(result).not.toContain("unknown-file.md");
+		expect(result).not.toContain("This should NOT appear.");
+	});
+
+	test("skips files that cannot be read", () => {
+		writeFileSync(join(testDir, "corrections.md"), "# Good File\n\nContent here.");
+		// Create a file but then remove it to simulate read failure scenario
+		const badPath = join(testDir, "principles.md");
+		writeFileSync(badPath, "temp");
+		rmSync(badPath);
+
+		const result = buildConfigMemory(testDir);
+
+		// Should still process the good file
+		expect(result).toContain("corrections.md");
+		expect(result).toContain("Content here.");
+		// Should not fail, just skip the missing file
+		expect(result).not.toContain("principles.md");
+	});
+
+	test("handles all known memory files", () => {
+		const knownFiles = ["corrections.md", "principles.md", "heartbeat-log.md", "presence-log.md"];
+
+		for (const fileName of knownFiles) {
+			writeFileSync(join(testDir, fileName), `# ${fileName}\n\nTest content for ${fileName}`);
+		}
+
+		const result = buildConfigMemory(testDir);
+
+		for (const fileName of knownFiles) {
+			expect(result).toContain(`## ${fileName}`);
+			expect(result).toContain(`Test content for ${fileName}`);
+		}
+	});
+
+	test("excludes agent-notes.md to avoid feedback loop", () => {
+		writeFileSync(join(testDir, "agent-notes.md"), "# Agent Notes\n\nThis should NOT appear.");
+		writeFileSync(join(testDir, "corrections.md"), "# Corrections\n\nThis should appear.");
+
+		const result = buildConfigMemory(testDir);
+
+		expect(result).not.toContain("agent-notes.md");
+		expect(result).not.toContain("This should NOT appear.");
+		expect(result).toContain("corrections.md");
+		expect(result).toContain("This should appear.");
+	});
+});

src/agent/prompt-blocks/config-memory.ts

@@ -0,0 +1,56 @@
+import { existsSync, readFileSync } from "node:fs";
+import { join } from "node:path";
+
+// Known append-only memory files in phantom-config/memory/ that the agent
+// writes during evolution and that we need to truncate to avoid SDK auto-
+// include size budget truncation. Each file is processed independently and
+// returned as a subsection.
+//
+// NOTE: agent-notes.md is explicitly excluded. The agent reads its own
+// writes with the Read tool when needed, avoiding a feedback loop that
+// would re-present the agent's past entries as canonical context on every
+// query (see prompt-assembler.ts section 6b comment).
+const KNOWN_MEMORY_FILES = ["corrections.md", "principles.md", "heartbeat-log.md", "presence-log.md"];
+
+// Reads memory files from phantom-config/memory/ and truncates each to
+// MAX_LINES with a compaction warning so unbounded append-only logs cannot
+// blow up the context window. Returns an empty string when no files exist.
+export function buildConfigMemory(configMemoryDir: string): string {
+	const sections: string[] = [];
+	const MAX_LINES = 100;
+
+	for (const fileName of KNOWN_MEMORY_FILES) {
+		const filePath = join(configMemoryDir, fileName);
+		try {
+			if (!existsSync(filePath)) continue;
+			const content = readFileSync(filePath, "utf-8").trim();
+			if (!content) continue;
+
+			const lines = content.split("\n");
+			let processedContent: string;
+
+			if (lines.length > MAX_LINES) {
+				const header = lines.slice(0, 3);
+				const recent = lines.slice(-(MAX_LINES - 5));
+				const truncated = [
+					...header,
+					"",
+					`<!-- ${fileName} was truncated. Please compact this file. -->`,
+					"",
+					...recent,
+				].join("\n");
+				processedContent = truncated;
+			} else {
+				processedContent = content;
+			}
+
+			sections.push(`## ${fileName}\n\n${processedContent}`);
+		} catch {
+			// Skip files that cannot be read
+		}
+	}
+
+	if (sections.length === 0) return "";
+
+	return `# Config Memory Files\n\nThese files contain your learnings and observations from past sessions. They live in phantom-config/memory/ and grow over time.\n\n${sections.join("\n\n")}`;
+}