Move skill command handling to AgentSession, update docs

- Skill commands (/skill:name) now expanded in AgentSession instead of
  interactive mode, enabling them in RPC and print modes
- Input event can now intercept /skill:name before expansion
- Updated extensions.md with clearer input event docs and processing order
- Updated rpc.md: hook -> extension terminology, added skill expansion mentions
- Added PR attribution to changelog entries for #761

.pi/extensions/git-diff/index.ts

@@ -1,27 +1,13 @@
 /**
- * Git Diff Extension
- *
- * Shows modified/added/removed files in the git worktree and displays their diffs.
- *
- * Usage:
- * - Press Ctrl+F or type /diff to open the file picker
- * - Select a file to view its diff
- * - Use Up/Down or Left/Right to scroll the diff
- * - Press Escape to close
+ * Git Diff Extension - Ctrl+F or /diff to view git changes
  */
 
+import { appendFileSync } from "node:fs";
+import { readFile } from "node:fs/promises";
+import { join } from "node:path";
 import type { ExtensionAPI, ExtensionContext, Theme } from "@mariozechner/pi-coding-agent";
-import { DynamicBorder } from "@mariozechner/pi-coding-agent";
-import {
-	Container,
-	Key,
-	matchesKey,
-	type SelectItem,
-	SelectList,
-	Text,
-	truncateToWidth,
-	visibleWidth,
-} from "@mariozechner/pi-tui";
+import { DynamicBorder, generateDiffString, renderDiff } from "@mariozechner/pi-coding-agent";
+import { Container, Key, matchesKey, type SelectItem, SelectList, Text, truncateToWidth, visibleWidth } from "@mariozechner/pi-tui";
 
 interface GitFile {
 	status: "M" | "A" | "D" | "R" | "C" | "U" | "?";
@@ -29,383 +15,148 @@ interface GitFile {
 	staged: boolean;
 }
 
-type FileStatus = GitFile["status"];
-
-const STATUS_LABELS: Record<FileStatus, string> = {
-	M: "modified",
-	A: "added",
-	D: "deleted",
-	R: "renamed",
-	C: "copied",
-	U: "unmerged",
-	"?": "untracked",
+const STATUS_LABELS: Record<GitFile["status"], string> = {
+	M: "modified", A: "added", D: "deleted", R: "renamed", C: "copied", U: "unmerged", "?": "untracked",
 };
+const dbg = (msg: string) => appendFileSync("/tmp/git-diff-debug.log", msg + "\n");
 
-const STATUS_COLORS: Record<FileStatus, "warning" | "success" | "error" | "muted"> = {
-	M: "warning",
-	A: "success",
-	D: "error",
-	R: "warning",
-	C: "warning",
-	U: "error",
-	"?": "muted",
-};
-
-/**
- * Parse git status --porcelain output into file list
- */
 function parseGitStatus(output: string): GitFile[] {
+	dbg(`=== parseGitStatus ===`);
+	dbg(`Raw output: ${JSON.stringify(output)}`);
 	const files: GitFile[] = [];
-	const lines = output.trim().split("\n").filter(Boolean);
-
-	for (const line of lines) {
-		if (line.length < 3) continue;
-
-		const indexStatus = line[0];
-		const workTreeStatus = line[1];
-		const path = line.slice(3);
-
-		// Staged changes (index has status, worktree is space or has same status)
-		if (indexStatus !== " " && indexStatus !== "?") {
-			files.push({
-				status: indexStatus as FileStatus,
-				path,
-				staged: true,
-			});
-		}
-
-		// Unstaged changes (worktree has status different from index)
-		if (workTreeStatus !== " " && workTreeStatus !== "?") {
-			// Don't duplicate if same status in both
-			if (indexStatus === " " || indexStatus !== workTreeStatus) {
-				files.push({
-					status: workTreeStatus as FileStatus,
-					path,
-					staged: false,
-				});
-			}
-		}
-
-		// Untracked files
-		if (indexStatus === "?" && workTreeStatus === "?") {
-			files.push({
-				status: "?",
-				path,
-				staged: false,
-			});
-		}
+	for (const line of output.trim().split("\n").filter(Boolean)) {
+		dbg(`Line: ${JSON.stringify(line)} (len=${line.length})`);
+		if (line.length < 4) { dbg("  Skipped: too short"); continue; }
+		const idx = line[0], wt = line[1], path = line.slice(3);
+		dbg(`  idx='${idx}' wt='${wt}' path='${path}'`);
+		if (idx !== " " && idx !== "?") { dbg(`  -> staged`); files.push({ status: idx as GitFile["status"], path, staged: true }); }
+		if (wt !== " " && wt !== "?" && (idx === " " || idx !== wt)) { dbg(`  -> unstaged`); files.push({ status: wt as GitFile["status"], path, staged: false }); }
+		if (idx === "?" && wt === "?") { dbg(`  -> untracked`); files.push({ status: "?", path, staged: false }); }
 	}
-
+	dbg(`Files: ${JSON.stringify(files)}`);
 	return files;
 }
 
-/**
- * Render a unified diff with colors
- */
-function renderUnifiedDiff(diffText: string, theme: Theme): string[] {
-	const lines = diffText.split("\n");
-	const result: string[] = [];
-
-	for (const line of lines) {
-		if (line.startsWith("+++") || line.startsWith("---")) {
-			// File headers
-			result.push(theme.fg("muted", line));
-		} else if (line.startsWith("@@")) {
-			// Hunk headers
-			result.push(theme.fg("accent", line));
-		} else if (line.startsWith("+")) {
-			result.push(theme.fg("toolDiffAdded", line));
-		} else if (line.startsWith("-")) {
-			result.push(theme.fg("toolDiffRemoved", line));
-		} else if (line.startsWith("diff --git")) {
-			result.push(theme.fg("dim", line));
-		} else if (line.startsWith("index ") || line.startsWith("new file") || line.startsWith("deleted file")) {
-			result.push(theme.fg("dim", line));
-		} else {
-			result.push(theme.fg("toolDiffContext", line));
-		}
-	}
-
-	return result;
-}
-
-/**
- * Scrollable diff viewer component
- */
 class DiffViewer {
-	private lines: string[] = [];
-	private scrollOffset = 0;
-	private viewportHeight = 20;
-	private filePath: string;
-
+	private lines: string[];
+	private offset = 0;
+	private height = 20;
 	onClose?: () => void;
 
-	constructor(
-		private theme: Theme,
-		filePath: string,
-		diffText: string,
-	) {
-		this.filePath = filePath;
-		this.lines = renderUnifiedDiff(diffText, theme);
+	constructor(private theme: Theme, private path: string, diff: string) {
+		this.lines = renderDiff(diff).split("\n");
 	}
 
 	handleInput(data: string): void {
-		const maxScroll = Math.max(0, this.lines.length - this.viewportHeight + 4);
-
-		if (matchesKey(data, Key.escape)) {
-			this.onClose?.();
-		} else if (matchesKey(data, Key.up) || matchesKey(data, Key.left)) {
-			this.scrollOffset = Math.max(0, this.scrollOffset - 1);
-		} else if (matchesKey(data, Key.down) || matchesKey(data, Key.right)) {
-			this.scrollOffset = Math.min(maxScroll, this.scrollOffset + 1);
-		} else if (matchesKey(data, Key.pageUp) || matchesKey(data, "shift+up")) {
-			this.scrollOffset = Math.max(0, this.scrollOffset - this.viewportHeight);
-		} else if (matchesKey(data, Key.pageDown) || matchesKey(data, "shift+down")) {
-			this.scrollOffset = Math.min(maxScroll, this.scrollOffset + this.viewportHeight);
-		} else if (matchesKey(data, Key.home) || matchesKey(data, "g")) {
-			this.scrollOffset = 0;
-		} else if (matchesKey(data, Key.end) || matchesKey(data, "shift+g")) {
-			this.scrollOffset = maxScroll;
-		}
+		const max = Math.max(0, this.lines.length - this.height + 4);
+		if (matchesKey(data, Key.escape)) this.onClose?.();
+		else if (matchesKey(data, Key.up) || matchesKey(data, Key.left)) this.offset = Math.max(0, this.offset - 1);
+		else if (matchesKey(data, Key.down) || matchesKey(data, Key.right)) this.offset = Math.min(max, this.offset + 1);
+		else if (matchesKey(data, Key.pageUp)) this.offset = Math.max(0, this.offset - this.height);
+		else if (matchesKey(data, Key.pageDown)) this.offset = Math.min(max, this.offset + this.height);
+		else if (matchesKey(data, "g")) this.offset = 0;
+		else if (matchesKey(data, "shift+g")) this.offset = max;
 	}
 
 	render(width: number): string[] {
-		const th = this.theme;
-		const result: string[] = [];
-		const innerWidth = width - 2;
+		const th = this.theme, w = width - 2, out: string[] = [];
+		const visible = this.lines.slice(this.offset, this.offset + this.height);
+		const row = (c: string) => th.fg("border", "│") + c + " ".repeat(Math.max(0, w - visibleWidth(c))) + th.fg("border", "│");
 
-		// Calculate viewport (leave room for header, footer, borders)
-		this.viewportHeight = Math.max(5, 20);
-
-		const maxScroll = Math.max(0, this.lines.length - this.viewportHeight + 4);
-		const visibleLines = this.lines.slice(this.scrollOffset, this.scrollOffset + this.viewportHeight);
-
-		// Helper to create bordered line
-		const row = (content: string) => {
-			const vis = visibleWidth(content);
-			const padding = Math.max(0, innerWidth - vis);
-			return th.fg("border", "│") + content + " ".repeat(padding) + th.fg("border", "│");
-		};
-
-		// Top border
-		result.push(th.fg("border", "╭" + "─".repeat(innerWidth) + "╮"));
-
-		// Header with file path
-		const header = ` ${th.fg("accent", th.bold(truncateToWidth(this.filePath, innerWidth - 2)))}`;
-		result.push(row(header));
-		result.push(row(""));
-
-		// Diff content
-		for (const line of visibleLines) {
-			result.push(row(" " + truncateToWidth(line, innerWidth - 2)));
-		}
-
-		// Pad if fewer lines than viewport
-		const paddingNeeded = this.viewportHeight - visibleLines.length;
-		for (let i = 0; i < paddingNeeded; i++) {
-			result.push(row(""));
-		}
-
-		// Scroll indicator
-		const scrollInfo =
-			this.lines.length > this.viewportHeight
-				? `${this.scrollOffset + 1}-${Math.min(this.scrollOffset + this.viewportHeight, this.lines.length)} of ${this.lines.length}`
-				: `${this.lines.length} lines`;
-		result.push(row(""));
-		result.push(row(` ${th.fg("dim", scrollInfo)}`));
-
-		// Footer with help
-		result.push(row(` ${th.fg("dim", "↑↓/←→ scroll • PgUp/PgDn page • g/G start/end • Esc close")}`));
-
-		// Bottom border
-		result.push(th.fg("border", "╰" + "─".repeat(innerWidth) + "╯"));
-
-		return result;
+		out.push(th.fg("border", "╭" + "─".repeat(w) + "╮"));
+		out.push(row(` ${th.fg("accent", th.bold(truncateToWidth(this.path, w - 2)))}`));
+		out.push(row(""));
+		for (const l of visible) out.push(row(" " + truncateToWidth(l, w - 2)));
+		for (let i = visible.length; i < this.height; i++) out.push(row(""));
+		const info = this.lines.length > this.height ? `${this.offset + 1}-${Math.min(this.offset + this.height, this.lines.length)} of ${this.lines.length}` : `${this.lines.length} lines`;
+		out.push(row(""));
+		out.push(row(` ${th.fg("dim", info)}`));
+		out.push(row(` ${th.fg("dim", "↑↓/←→ scroll • PgUp/PgDn • g/G • Esc")}`));
+		out.push(th.fg("border", "╰" + "─".repeat(w) + "╯"));
+		return out;
 	}
 
 	invalidate(): void {}
 }
 
-/**
- * Show the diff for a file
- */
-async function showFileDiff(file: GitFile, ctx: ExtensionContext, pi: ExtensionAPI): Promise<void> {
-	// Get the diff
-	let diffArgs: string[];
+async function getDiff(file: GitFile, ctx: ExtensionContext, pi: ExtensionAPI): Promise<{ diff: string } | { error: string }> {
+	const abs = join(ctx.cwd, file.path);
+
 	if (file.status === "?") {
-		// Untracked file: show full content as "added"
-		const result = await pi.exec("cat", [file.path], { cwd: ctx.cwd });
-		if (result.code !== 0) {
-			ctx.ui.notify(`Failed to read ${file.path}`, "error");
-			return;
-		}
-		// Create a fake diff showing all lines as added
-		const lines = result.stdout.split("\n");
-		const diffText = [
-			`diff --git a/${file.path} b/${file.path}`,
-			"new file",
-			`--- /dev/null`,
-			`+++ b/${file.path}`,
-			`@@ -0,0 +1,${lines.length} @@`,
-			...lines.map((l) => "+" + l),
-		].join("\n");
-
-		await showDiffViewer(file.path, diffText, ctx);
-		return;
+		try { return { diff: generateDiffString("", await readFile(abs, "utf-8")).diff }; }
+		catch (e) { return { error: `Read failed: ${e}` }; }
 	}
 
+	if (file.status === "D") {
+		const r = await pi.exec("git", ["show", `HEAD:${file.path}`], { cwd: ctx.cwd });
+		return r.code === 0 ? { diff: generateDiffString(r.stdout, "").diff } : { error: `Git show failed: ${r.stderr}` };
+	}
+
+	let old = "", cur = "";
 	if (file.staged) {
-		diffArgs = ["diff", "--cached", "--", file.path];
+		const h = await pi.exec("git", ["show", `HEAD:${file.path}`], { cwd: ctx.cwd });
+		old = h.code === 0 ? h.stdout : "";
+		const i = await pi.exec("git", ["show", `:${file.path}`], { cwd: ctx.cwd });
+		if (i.code !== 0) return { error: `Staged content failed for '${file.path}': ${i.stderr}` };
+		cur = i.stdout;
 	} else {
-		diffArgs = ["diff", "--", file.path];
+		const i = await pi.exec("git", ["show", `:${file.path}`], { cwd: ctx.cwd });
+		old = i.code === 0 ? i.stdout : (await pi.exec("git", ["show", `HEAD:${file.path}`], { cwd: ctx.cwd })).stdout || "";
+		try { cur = await readFile(abs, "utf-8"); }
+		catch (e) { return { error: `Read failed: ${e}` }; }
 	}
-
-	const result = await pi.exec("git", diffArgs, { cwd: ctx.cwd });
-	if (result.code !== 0) {
-		ctx.ui.notify(`Failed to get diff for ${file.path}: ${result.stderr}`, "error");
-		return;
-	}
-
-	if (!result.stdout.trim()) {
-		ctx.ui.notify(`No diff available for ${file.path}`, "info");
-		return;
-	}
-
-	await showDiffViewer(file.path, result.stdout, ctx);
+	return { diff: generateDiffString(old, cur).diff };
 }
 
-async function showDiffViewer(filePath: string, diffText: string, ctx: ExtensionContext): Promise<void> {
-	await ctx.ui.custom<void>((tui, theme, _kb, done) => {
-		const viewer = new DiffViewer(theme, filePath, diffText);
-		viewer.onClose = () => done();
-
-		return {
-			render: (w) => viewer.render(w),
-			invalidate: () => viewer.invalidate(),
-			handleInput: (data) => {
-				viewer.handleInput(data);
-				tui.requestRender();
-			},
-		};
+async function showViewer(path: string, diff: string, ctx: ExtensionContext): Promise<void> {
+	await ctx.ui.custom<void>((tui, theme, _, done) => {
+		const v = new DiffViewer(theme, path, diff);
+		v.onClose = () => done();
+		return { render: (w) => v.render(w), invalidate: () => v.invalidate(), handleInput: (d) => { v.handleInput(d); tui.requestRender(); } };
 	}, { overlay: true });
 }
 
-/**
- * Show the file picker overlay
- */
-async function showFilePicker(files: GitFile[], ctx: ExtensionContext, pi: ExtensionAPI): Promise<void> {
-	// Group files by status
-	const items: SelectItem[] = files.map((file) => {
-		const statusLabel = STATUS_LABELS[file.status];
-		const stagedLabel = file.staged ? " (staged)" : "";
-		return {
-			value: file,
-			label: file.path,
-			description: `${statusLabel}${stagedLabel}`,
-		};
-	});
+async function showPicker(files: GitFile[], ctx: ExtensionContext, pi: ExtensionAPI): Promise<void> {
+	const items: SelectItem[] = files.map((f, i) => ({ value: i, label: f.path, description: `${STATUS_LABELS[f.status]}${f.staged ? " (staged)" : ""}` }));
 
-	const result = await ctx.ui.custom<GitFile | null>((tui, theme, _kb, done) => {
-		const container = new Container();
-
-		// Top border
-		container.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));
-
-		// Title
-		const title = new Text(theme.fg("accent", theme.bold("Git Changes")) + theme.fg("dim", ` (${files.length} files)`), 1, 0);
-		container.addChild(title);
-
-		// File list
-		const selectList = new SelectList(items, Math.min(items.length, 15), {
-			selectedPrefix: (t) => theme.fg("accent", t),
-			selectedText: (t) => theme.fg("accent", t),
-			description: (t) => {
-				// Color description based on status keyword
-				if (t.startsWith("modified")) return theme.fg("warning", t);
-				if (t.startsWith("added")) return theme.fg("success", t);
-				if (t.startsWith("deleted")) return theme.fg("error", t);
-				if (t.startsWith("untracked")) return theme.fg("muted", t);
-				if (t.startsWith("renamed") || t.startsWith("copied")) return theme.fg("warning", t);
-				if (t.startsWith("unmerged")) return theme.fg("error", t);
-				return theme.fg("muted", t);
-			},
-			scrollInfo: (t) => theme.fg("dim", t),
-			noMatch: (t) => theme.fg("warning", t),
+	const idx = await ctx.ui.custom<number | null>((tui, theme, _, done) => {
+		const c = new Container();
+		c.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));
+		c.addChild(new Text(`${theme.fg("accent", theme.bold("Git Changes"))} ${theme.fg("dim", `(${files.length})`)}`, 1, 0));
+		const list = new SelectList(items, Math.min(items.length, 15), {
+			selectedPrefix: (t) => theme.fg("accent", t), selectedText: (t) => theme.fg("accent", t),
+			description: (t) => theme.fg(t.startsWith("modified") ? "warning" : t.startsWith("added") ? "success" : t.startsWith("deleted") ? "error" : "muted", t),
+			scrollInfo: (t) => theme.fg("dim", t), noMatch: (t) => theme.fg("warning", t),
 		});
-
-		selectList.onSelect = (item) => done(item.value as GitFile);
-		selectList.onCancel = () => done(null);
-		container.addChild(selectList);
-
-		// Help text
-		container.addChild(new Text(theme.fg("dim", "↑↓ navigate • enter select • type to filter • esc close"), 1, 0));
-
-		// Bottom border
-		container.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));
-
-		return {
-			render: (w) => container.render(w),
-			invalidate: () => container.invalidate(),
-			handleInput: (data) => {
-				selectList.handleInput(data);
-				tui.requestRender();
-			},
-		};
+		list.onSelect = (item) => done(item.value as number);
+		list.onCancel = () => done(null);
+		c.addChild(list);
+		c.addChild(new Text(theme.fg("dim", "↑↓ nav • enter select • type filter • esc close"), 1, 0));
+		c.addChild(new DynamicBorder((s: string) => theme.fg("accent", s)));
+		return { render: (w) => c.render(w), invalidate: () => c.invalidate(), handleInput: (d) => { list.handleInput(d); tui.requestRender(); } };
 	}, { overlay: true });
 
-	if (result) {
-		await showFileDiff(result, ctx, pi);
-		// After viewing diff, show file picker again
-		await showFilePicker(files, ctx, pi);
+	if (idx !== null) {
+		const file = files[idx];
+		const r = await getDiff(file, ctx, pi);
+		if ("error" in r) ctx.ui.notify(r.error, "error");
+		else if (!r.diff.trim()) ctx.ui.notify(`No changes in ${file.path}`, "info");
+		else await showViewer(file.path, r.diff, ctx);
+		await showPicker(files, ctx, pi);
 	}
 }
 
-/**
- * Main handler for showing the diff overlay
- */
-async function showDiffOverlay(ctx: ExtensionContext, pi: ExtensionAPI): Promise<void> {
-	// Check if we're in a git repo
-	const gitCheck = await pi.exec("git", ["rev-parse", "--git-dir"], { cwd: ctx.cwd });
-	if (gitCheck.code !== 0) {
-		ctx.ui.notify("Not in a git repository", "error");
-		return;
-	}
-
-	// Get changed files
-	const statusResult = await pi.exec("git", ["status", "--porcelain"], { cwd: ctx.cwd });
-	if (statusResult.code !== 0) {
-		ctx.ui.notify(`Git status failed: ${statusResult.stderr}`, "error");
-		return;
-	}
-
-	if (!statusResult.stdout.trim()) {
-		ctx.ui.notify("No changes in working tree", "info");
-		return;
-	}
-
-	const files = parseGitStatus(statusResult.stdout);
-	if (files.length === 0) {
-		ctx.ui.notify("No changes in working tree", "info");
-		return;
-	}
-
-	await showFilePicker(files, ctx, pi);
+async function run(ctx: ExtensionContext, pi: ExtensionAPI): Promise<void> {
+	if ((await pi.exec("git", ["rev-parse", "--git-dir"], { cwd: ctx.cwd })).code !== 0) { ctx.ui.notify("Not a git repo", "error"); return; }
+	const s = await pi.exec("git", ["status", "--porcelain"], { cwd: ctx.cwd });
+	if (s.code !== 0) { ctx.ui.notify(`Git failed: ${s.stderr}`, "error"); return; }
+	if (!s.stdout.trim()) { ctx.ui.notify("No changes", "info"); return; }
+	const files = parseGitStatus(s.stdout);
+	if (!files.length) { ctx.ui.notify("No changes", "info"); return; }
+	await showPicker(files, ctx, pi);
 }
 
-export default function gitDiffExtension(pi: ExtensionAPI) {
-	// Register Ctrl+F shortcut
-	pi.registerShortcut(Key.ctrl("f"), {
-		description: "Show git diff overlay",
-		handler: async (ctx) => {
-			await showDiffOverlay(ctx, pi);
-		},
-	});
-
-	// Register /diff command
-	pi.registerCommand("diff", {
-		description: "Show modified files and their diffs",
-		handler: async (_args, ctx) => {
-			await showDiffOverlay(ctx, pi);
-		},
-	});
+export default function (pi: ExtensionAPI) {
+	pi.registerShortcut(Key.ctrl("f"), { description: "Git diff overlay", handler: (ctx) => run(ctx, pi) });
+	pi.registerCommand("diff", { description: "Show git changes", handler: (_, ctx) => run(ctx, pi) });
 }