feat(simplify): track file hashes to prevent repeated simplification proposals (#32)

* feat(simplify): track file hashes to prevent repeated simplification proposals

* docs: update changelog

Author: kostyay

CHANGELOG.md

@@ -60,7 +60,13 @@ All notable changes to agent-stuff are documented here.
 
 
 
-## docs/auto-generated-file-filtering
+
+
+## feat/persist-simplification-hashes
+
+The simplify extension now persists content hashes of simplified files to prevent repeated simplification proposals (#32). After each simplification run, file hashes are stored in `$PI_CODING_AGENT_DIR/simplify-hashes.json` and checked before proposing future simplifications, ensuring proposals only appear when file content actually changes. This eliminates redundant suggestions that occurred when the simplification tool itself modified files, improving the user experience by reducing unnecessary prompts while maintaining the ability to re-simplify genuinely modified code.
+
+## [1.0.20](https://github.com/kostyay/agent-stuff/pull/31) - 2026-03-07
 
 Updated changelog writing rules and commit guidance to exclude auto-generated files from summaries and descriptions (#31). The changelog writer, commit message guidelines, and PR update skill now consistently ignore lock files (package-lock.json, yarn.lock, pnpm-lock.yaml, go.sum, Cargo.lock), generated code (*.pb.go, *_generated.*, *.gen.*), and build artifacts (dist/, *.min.js, *.min.css) to reduce noise and keep focus on meaningful hand-written changes. This ensures that changelog entries and commit descriptions accurately reflect actual development work rather than dependency or build system artifacts.
 

pi-extensions/simplify.ts

@@ -10,15 +10,18 @@
  *
  * Hooks into `agent_end` to propose running `/simplify` when source files
  * were modified during the agent's turn. Shows a timed confirmation that
- * auto-accepts after 5 seconds.
+ * auto-accepts after 5 seconds. Files are only proposed once — after
+ * simplification their content hashes are persisted and checked before
+ * any subsequent proposal.
  *
  * To add a new language:
  *   1. Create `skills/<lang>-code-simplifier/SKILL.md`
  *   2. Add one entry to FILE_EXTENSIONS below
  */
 
 import type { ExtensionAPI, ExtensionContext } from "@mariozechner/pi-coding-agent";
-import { existsSync, readFileSync, readdirSync } from "node:fs";
+import { createHash } from "node:crypto";
+import { existsSync, mkdirSync, readFileSync, readdirSync, writeFileSync } from "node:fs";
 import { dirname, extname, join, resolve } from "node:path";
 import { fileURLToPath } from "node:url";
 
@@ -142,6 +145,16 @@ function filterByLanguage(files: string[], lang: string): string[] {
 	return files.filter((f) => FILE_EXTENSIONS[fileExtension(f)] === lang);
 }
 
+/** SHA-256 hash of a file's content. Returns null if the file can't be read. */
+function hashFile(filePath: string): string | null {
+	try {
+		const content = readFileSync(filePath);
+		return createHash("sha256").update(content).digest("hex");
+	} catch {
+		return null;
+	}
+}
+
 // ---------------------------------------------------------------------------
 // Settings
 // ---------------------------------------------------------------------------
@@ -180,6 +193,56 @@ function readSettings(): SimplifySettings {
 	}
 }
 
+// ---------------------------------------------------------------------------
+// Persisted simplification hashes
+// ---------------------------------------------------------------------------
+
+/** Keyed by cwd so different projects don't collide. */
+type HashStore = Record<string, Record<string, string>>;
+
+/** Resolve the path to the hash store file. Returns null when unconfigured. */
+function hashStorePath(): string | null {
+	const configDir = process.env.PI_CODING_AGENT_DIR;
+	if (!configDir) return null;
+	return join(configDir, "simplify-hashes.json");
+}
+
+/** Load persisted hashes for the current working directory. */
+function loadHashes(): Map<string, string> {
+	const path = hashStorePath();
+	if (!path || !existsSync(path)) return new Map();
+
+	try {
+		const store = JSON.parse(readFileSync(path, "utf-8")) as HashStore;
+		const project = store[process.cwd()];
+		if (!project || typeof project !== "object") return new Map();
+		return new Map(Object.entries(project));
+	} catch {
+		return new Map();
+	}
+}
+
+/** Persist hashes for the current working directory. */
+function saveHashes(hashes: Map<string, string>): void {
+	const path = hashStorePath();
+	if (!path) return;
+
+	let store: HashStore = {};
+	try {
+		if (existsSync(path)) {
+			store = JSON.parse(readFileSync(path, "utf-8")) as HashStore;
+		}
+	} catch {
+		store = {};
+	}
+
+	store[process.cwd()] = Object.fromEntries(hashes);
+
+	const dir = dirname(path);
+	if (!existsSync(dir)) mkdirSync(dir, { recursive: true });
+	writeFileSync(path, JSON.stringify(store, null, "\t"), "utf-8");
+}
+
 // ---------------------------------------------------------------------------
 // Git helpers
 // ---------------------------------------------------------------------------
@@ -355,7 +418,7 @@ async function triggerSimplify(
 	const relevantFiles = filterByLanguage(files, lang);
 	notify(`Simplifying ${relevantFiles.length} ${lang.toUpperCase()} file(s)…`, "info");
 
-	simplifyPending = true;
+	pendingSimplifyFiles = relevantFiles;
 	pi.sendUserMessage(buildPrompt(skillContent, relevantFiles, options.extraInstructions));
 	return true;
 }
@@ -404,17 +467,22 @@ function wasAborted(event: unknown): boolean {
 let statsAtStart: Map<string, FileStats> = new Map();
 
 /**
- * Whether simplify has already been proposed since the last user-initiated
- * prompt. Prevents re-proposing after the simplification run itself
- * modifies files. Only reset when the user types a new prompt.
+ * Content hashes of files after their last simplification pass.
+ *
+ * Loaded from `$PI_CODING_AGENT_DIR/simplify-hashes.json` on startup,
+ * updated and persisted after each simplification run. Keyed by relative
+ * file path so proposals are suppressed until the file actually changes.
  */
-let hasProposedSimplify = false;
+const simplifiedHashes: Map<string, string> = loadHashes();
 
 /**
- * Set by `triggerSimplify` before `sendUserMessage` so `before_agent_start`
- * can distinguish programmatic turns from user-initiated ones.
+ * Files being simplified in the current agent turn.
+ *
+ * Set by `triggerSimplify` before `sendUserMessage`. When `agent_end`
+ * sees this is non-null, it hashes the files, persists them, and skips
+ * the proposal.
  */
-let simplifyPending = false;
+let pendingSimplifyFiles: string[] | null = null;
 
 /**
  * Files queued by the `agent_end` auto-simplify confirmation.
@@ -433,10 +501,6 @@ export default function simplifyExtension(pi: ExtensionAPI) {
 	// ── Snapshot dirty files at turn start ──────────────────────────
 
 	pi.on("before_agent_start", async () => {
-		if (!simplifyPending) {
-			hasProposedSimplify = false;
-		}
-		simplifyPending = false;
 		statsAtStart = await snapshotFileStats(pi);
 	});
 
@@ -472,7 +536,18 @@ export default function simplifyExtension(pi: ExtensionAPI) {
 	// ── Auto-simplify proposal after agent turn ─────────────────────
 
 	pi.on("agent_end", async (event: unknown, ctx: ExtensionContext) => {
-		if (!ctx.hasUI || hasProposedSimplify) return;
+		// After a simplify turn, hash the output files and persist.
+		if (pendingSimplifyFiles) {
+			for (const file of pendingSimplifyFiles) {
+				const hash = hashFile(file);
+				if (hash) simplifiedHashes.set(file, hash);
+			}
+			pendingSimplifyFiles = null;
+			saveHashes(simplifiedHashes);
+			return;
+		}
+
+		if (!ctx.hasUI) return;
 		if (wasAborted(event)) return;
 
 		const statsAtEnd = await snapshotFileStats(pi);
@@ -488,27 +563,34 @@ export default function simplifyExtension(pi: ExtensionAPI) {
 		const relevantFiles = filterByLanguage(sourceFiles, lang);
 		if (relevantFiles.length === 0) return;
 
+		// Skip files whose content hasn't changed since last simplification.
+		const unsimplified = relevantFiles.filter((f) => {
+			const currentHash = hashFile(f);
+			if (!currentHash) return false;
+			const storedHash = simplifiedHashes.get(f);
+			return !storedHash || currentHash !== storedHash;
+		});
+		if (unsimplified.length === 0) return;
+
 		const { minChangedLines } = readSettings();
 		if (minChangedLines > 0) {
 			let totalDelta = 0;
-			for (const file of relevantFiles) {
+			for (const file of unsimplified) {
 				totalDelta += modified.get(file) ?? 0;
 			}
 			if (totalDelta < minChangedLines) return;
 		}
 
-		hasProposedSimplify = true;
-
 		const confirmed = await timedConfirm(ctx, {
 			title: "Simplify code",
-			message: buildConfirmMessage(relevantFiles, lang),
+			message: buildConfirmMessage(unsimplified, lang),
 			seconds: 5,
 			defaultValue: true,
 		});
 
 		if (!confirmed) return;
 
-		pendingAutoSimplifyFiles = sourceFiles;
+		pendingAutoSimplifyFiles = unsimplified;
 		pi.sendUserMessage("/simplify");
 	});
 }