[tab] src/extension.ts (typescript)
import * as vscode from 'vscode';
import * as http from 'http';
import { Buffer } from 'buffer';
import assert from 'assert';

const HOSTNAME = 'hai001';
const PORT = 30000;

export function activate(context: vscode.ExtensionContext) {

	console.log('[crowd-pilot] Extension activated');

	// Configure terminal to allow tab keybinding to work
	(async () => {
		const config = vscode.workspace.getConfiguration('terminal.integrated');
		const commandsToSkipShell = config.get<string[]>('commandsToSkipShell', []);
		let updated = false;
		if (!commandsToSkipShell.includes('crowd-pilot.modelRun')) {
			commandsToSkipShell.push('crowd-pilot.modelRun');
			updated = true;
		}
		if (!commandsToSkipShell.includes('crowd-pilot.hideUi')) {
			commandsToSkipShell.push('crowd-pilot.hideUi');
			updated = true;
		}
		if (updated) {
			await config.update('commandsToSkipShell', commandsToSkipShell, vscode.ConfigurationTarget.Global);
		}
	})().catch((err) => console.error('[crowd-pilot] Startup initialization error:', err));

	const hideUi = vscode.commands.registerCommand('crowd-pilot.hideUi', () => {
		hidePreviewUI(true);
	});

	const modelRun = vscode.commands.registerCommand('crowd-pilot.modelRun', async () => {
		const editor = vscode.window.activeTextEditor;
		if (!editor) {
			return;
		}
		try {
			// Confirm only when a suggestion is visible
			if (!previewVisible) { return; }
			let action: PlannedAction | undefined = currentAction;
			if (!action) {
				const single = await requestModelActions(editor);
				currentAction = single;
				action = single;
			}
			if (!action) {
				hidePreviewUI();
				return;
			}
			hidePreviewUI(false);
			await executeAction(action);
			autoShowNextAction();
		} catch (err) {
			const errorMessage = err instanceof Error ? err.message : String(err);
			vscode.window.showErrorMessage(`Model run failed: ${errorMessage}`);
		}
	});

	const sglangTest = vscode.commands.registerCommand('crowd-pilot.sglangTest', async () => {
		try {
			await callSGLangChat();
		} catch (err) {
			const errorMessage = err instanceof Error ? err.message : String(err);
			vscode.window.showErrorMessage(`SGLang test failed: ${errorMessage}`);
		}
	});

	// Auto-preview listeners
	const onSelChange = vscode.window.onDidChangeTextEditorSelection((e) => {
		if (e.textEditor === vscode.window.activeTextEditor) {
			suppressAutoPreview = false;
			autoShowNextAction();
		}
	});
	const onActiveChange = vscode.window.onDidChangeActiveTextEditor(() => {
		suppressAutoPreview = false;
		autoShowNextAction();
	});
	const onDocChange = vscode.workspace.onDidChangeTextDocument((e) => {
		if (vscode.window.activeTextEditor?.document === e.document) {
			suppressAutoPreview = false;
			autoShowNextAction();
		}
	});

	context.subscriptions.push(hideUi, sglangTest, modelRun, onSelChange, onActiveChange, onDocChange);
}

export function deactivate() {}

// -------------------- Plan Types & Execution --------------------
type PlannedAction =
| { kind: 'showTextDocument' }
| { kind: 'setSelections', selections: Array<{ start: [number, number], end: [number, number] }> }
| { kind: 'editInsert', position: [number, number], text: string }
| { kind: 'editDelete', range: { start: [number, number], end: [number, number] } }
| { kind: 'editReplace', range: { start: [number, number], end: [number, number] }, text: string }
| { kind: 'terminalShow' }
| { kind: 'terminalSendText', text: string };

let currentAction: PlannedAction | undefined;

async function executeAction(action: PlannedAction): Promise<void> {
	const editor = vscode.window.activeTextEditor;
	if (!editor) { return; }
	const doc = editor.document;
	const term = vscode.window.terminals[0] ?? vscode.window.createTerminal('Test');
	if (action.kind === 'showTextDocument') {
		await vscode.window.showTextDocument(doc);
		return;
	}
	if (action.kind === 'setSelections') {
		editor.selections = action.selections.map(s => new vscode.Selection(
			new vscode.Position(s.start[0], s.start[1]),
			new vscode.Position(s.end[0], s.end[1])
		));
		if (editor.selections.length > 0) {
			editor.revealRange(editor.selections[0], vscode.TextEditorRevealType.InCenterIfOutsideViewport);
		}
		return;
	}
	if (action.kind === 'editInsert') {
		await editor.edit((e: vscode.TextEditorEdit) => e.insert(new vscode.Position(action.position[0], action.position[1]), action.text));
		return;
	}
	if (action.kind === 'editDelete') {
		const range = new vscode.Range(
			new vscode.Position(action.range.start[0], action.range.start[1]),
			new vscode.Position(action.range.end[0], action.range.end[1])
		);
		await editor.edit((e: vscode.TextEditorEdit) => e.delete(range));
		return;
	}
	if (action.kind === 'editReplace') {
		const range = new vscode.Range(
			new vscode.Position(action.range.start[0], action.range.start[1]),
			new vscode.Position(action.range.end[0], action.range.end[1])
		);
		await editor.edit((e: vscode.TextEditorEdit) => e.replace(range, action.text));
		return;
	}
	if (action.kind === 'terminalShow') {
		term.show();
		return;
	}
	if (action.kind === 'terminalSendText') {
		term.sendText(action.text);
		return;
	}
}

// -------------------- UI State & Helpers --------------------
const UI_CONTEXT_KEY = 'crowdPilot.uiVisible';
let previewVisible = false;
let decorationDeleteType: vscode.TextEditorDecorationType | undefined;
let decorationReplaceType: vscode.TextEditorDecorationType | undefined;
let decorationReplaceBlockType: vscode.TextEditorDecorationType | undefined;
let mockStep = 0;
let suppressAutoPreview = false;

function disposePreviewDecorations() {
	try { decorationDeleteType?.dispose(); } catch {}
	try { decorationReplaceType?.dispose(); } catch {}
	try { decorationReplaceBlockType?.dispose(); } catch {}
	decorationDeleteType = undefined;
	decorationReplaceType = undefined;
	decorationReplaceBlockType = undefined;
}

function getDynamicMargin(editor: vscode.TextEditor, anchorLine: number, text: string): string {
	// Count lines in the preview text
	const lines = text.split(/
?
/);
	const height = lines.length;
	
	// We need to check the document lines that will be covered by this panel.
	// The panel starts at 'anchorLine' and extends downwards by 'height' lines.
	// However, visually, since it's 'after', it sits to the right of 'anchorLine',
	// and then flows down.
	// So we check document lines from anchorLine to anchorLine + height - 1.
	
	const doc = editor.document;
	let maxLen = 0;
	const startLine = anchorLine;
	const endLine = Math.min(doc.lineCount - 1, anchorLine + height - 1);
	
	for (let i = startLine; i <= endLine; i++) {
		const lineText = doc.lineAt(i).text;
		// Simple approximation: assume tabs are 4 spaces if we can't get config easily, 
		// or just treat them as 1 char (which might underestimate). 
		// Better to overestimate: treat tab as 4 chars.
		const len = lineText.replace(/	/g, '    ').length;
		if (len > maxLen) {
			maxLen = len;
		}
	}
	
	// Length of the anchor line itself
	const anchorLineText = doc.lineAt(anchorLine).text;
	const anchorLen = anchorLineText.replace(/	/g, '    ').length;
	
	// The offset needed is maxLen - anchorLen.
	// If maxLen <= anchorLen, offset is 0 (margin is just base padding).
	// If maxLen > anchorLen, we need to push right by (maxLen - anchorLen).
	
	const diff = Math.max(0, maxLen - anchorLen);
	// Base margin 2rem is roughly 4ch. Let's use ch units for everything to be consistent.
	// 1ch is width of '0'. In monospace, mostly consistent.
	// Add 3ch extra padding for safety/visual gap.
	const margin = diff + 4; 
	return `${margin}ch`;
}

function showPreviewUI(action: PlannedAction): void {
	const editor = vscode.window.activeTextEditor;
	if (!editor) { return; }
	disposePreviewDecorations();

	// FIXME (f.srambical): add file switch 
	const next = (action.kind === 'editInsert' || action.kind === 'editDelete' || action.kind === 'editReplace' || action.kind === 'terminalSendText' || action.kind === 'setSelections') ? action : undefined;
	if (!next) {
		previewVisible = false;
		vscode.commands.executeCommand('setContext', UI_CONTEXT_KEY, false);
		currentAction = action;
		return;
	}

	const trimText = (t: string) => {
		const oneLine = t.replace(/
?
/g, '\
');
		return oneLine.length > 80 ? oneLine.slice(0, 77) + '…' : oneLine;
	};

	if (next.kind === 'setSelections') {
		// For setSelections, we only preview the primary selection's start/active position
		const selection = next.selections[0];
		const targetPos = new vscode.Position(selection.start[0], selection.start[1]);
		// Check if the target position is visible
		const isVisible = editor.visibleRanges.some(r => r.contains(targetPos));
		
		let anchorPos = targetPos;
		let label = "↳ Move Cursor Here";

		if (!isVisible && editor.visibleRanges.length > 0) {
			const firstVisible = editor.visibleRanges[0].start;
			const lastVisible = editor.visibleRanges[editor.visibleRanges.length - 1].end;
			
			if (targetPos.isBefore(firstVisible)) {
				anchorPos = editor.document.lineAt(firstVisible.line).range.end;
			} else {
				anchorPos = editor.document.lineAt(lastVisible.line).range.end;
			}

			if (targetPos.line < anchorPos.line) {
				label = `↑ Move Cursor to Line ${targetPos.line + 1}`;
			} else {
				label = `↓ Move Cursor to Line ${targetPos.line + 1}`;
			}
		}

		const margin = getDynamicMargin(editor, anchorPos.line, label);

		decorationReplaceBlockType = vscode.window.createTextEditorDecorationType({
			after: {
				contentText: '',
				color: new vscode.ThemeColor('charts.purple'),
				backgroundColor: new vscode.ThemeColor('editor.background'),
				fontStyle: 'italic',
				fontWeight: '600',
				margin: `0 0 0 ${margin}`,
				textDecoration: `none; display: inline-block; white-space: pre; content: "${label}"; border: 1px solid var(--vscode-charts-purple); padding: 4px; border-radius: 4px; box-shadow: 0 4px 8px rgba(0,0,0,0.25); pointer-events: none; position: relative; z-index: 100; vertical-align: top;`
			}
		});
		editor.setDecorations(decorationReplaceBlockType, [{ range: new vscode.Range(anchorPos, anchorPos) }]);
	} else if (next.kind === 'terminalSendText') {
		const cursor = editor.selection.active;
		const lineEnd = editor.document.lineAt(cursor.line).range.end;
		const cmd = next.text.replace(/"/g, '\\"').replace(/
?
/g, '\\A ');
		const margin = getDynamicMargin(editor, cursor.line, "↳ Execute in Terminal:
" + next.text);

		decorationReplaceBlockType = vscode.window.createTextEditorDecorationType({
			after: {
				contentText: '',
				color: new vscode.ThemeColor('charts.purple'),
				backgroundColor: new vscode.ThemeColor('editor.background'),
				fontStyle: 'italic',
				fontWeight: '600',
				margin: `0 0 0 ${margin}`,
				textDecoration: `none; display: inline-block; white-space: pre; content: "↳ Execute in Terminal:\\A ${cmd}"; border: 1px solid var(--vscode-charts-purple); padding: 4px; border-radius: 4px; box-shadow: 0 4px 8px rgba(0,0,0,0.25); pointer-events: none; position: relative; z-index: 100; vertical-align: top;`
			}
		});
		editor.setDecorations(decorationReplaceBlockType, [{ range: new vscode.Range(lineEnd, lineEnd) }]);
	} else if (next.kind === 'editInsert') {
		const posLine = next.position[0];
		const fullBlock = next.text;
		const cssContent = fullBlock
			.replace(/"/g, '\\"')
			.replace(/
?
/g, '\\A ');

		const docLineCount = editor.document.lineCount;
		// If inserting at EOF (or beyond), attach to the last line.
		// Otherwise, attach to the line AT the insertion point and shift visually UP into the gap.
		let anchorLine = posLine;
		let shiftUp = true;
		
		if (anchorLine >= docLineCount) {
			anchorLine = docLineCount - 1;
			shiftUp = false; // At EOF, we just append below or to the right
		}

		const anchorPos = new vscode.Position(anchorLine, Number.MAX_VALUE); 
		
		// We attach to the line AT the insertion point.
		// The panel floats to the right of this line.
		// The dashed line connects the start of this line to the panel.
		// This indicates that the new text will be inserted at this line position (pushing the current line down).
		const marginCheckLine = anchorLine;
		const margin = getDynamicMargin(editor, marginCheckLine, fullBlock);

		const topOffset = '0';

		// Dashed line style
		// We use 'before' decoration for the line.
		// It needs to be absolute, full width (or enough to reach left), 
		// and aligned with the panel top.
		const beforeDecoration = {
			contentText: '',
			textDecoration: `none; position: absolute; left: 0; width: 100vw; border-top: 1px dashed var(--vscode-charts-purple); top: 0; height: 0; z-index: 99; pointer-events: none;`
		};

		decorationReplaceBlockType = vscode.window.createTextEditorDecorationType({
			before: beforeDecoration,
			after: {
				contentText: '',
				color: new vscode.ThemeColor('charts.purple'),
				backgroundColor: new vscode.ThemeColor('editor.background'),
				fontStyle: 'italic',
				fontWeight: '600',
				margin: `0 0 0 ${margin}`,
				textDecoration: `none; display: inline-block; white-space: pre; content: "${cssContent}"; border: 1px solid var(--vscode-charts-purple); padding: 4px; border-radius: 4px; box-shadow: 0 4px 8px rgba(0,0,0,0.25); pointer-events: none; position: relative; z-index: 100; vertical-align: top; top: ${topOffset};`
			}
		});
		editor.setDecorations(decorationReplaceBlockType, [{ range: new vscode.Range(anchorPos, anchorPos) }]);
	} else if (next.kind === 'editDelete') {
		const range = new vscode.Range(
			new vscode.Position(next.range.start[0], next.range.start[1]),
			new vscode.Position(next.range.end[0], next.range.end[1])
		);
		decorationDeleteType = vscode.window.createTextEditorDecorationType({
			backgroundColor: 'rgba(255, 60, 60, 0.18)',
			border: '1px solid rgba(255, 60, 60, 0.35)',
			textDecoration: 'line-through'
		});
		editor.setDecorations(decorationDeleteType, [{ range }]);
	} else if (next.kind === 'editReplace') {
		const range = new vscode.Range(
			new vscode.Position(next.range.start[0], next.range.start[1]),
			new vscode.Position(next.range.end[0], next.range.end[1])
		);
		// Highlight original range (to be replaced)
		decorationReplaceType = vscode.window.createTextEditorDecorationType({
			backgroundColor: 'rgba(255,165,0,0.15)',
			border: '1px dashed rgba(255,165,0,0.45)',
			color: new vscode.ThemeColor('disabledForeground'),
			textDecoration: 'line-through'
		});
		editor.setDecorations(decorationReplaceType, [{ range }]);

		// Show replacement block to the right of the first replaced line
		const fullBlock = next.text;
		
		// CSS-escape the text for the 'content' property:
		// - Escape double quotes
		// - Replace newlines with \A (CSS newline)
		const cssContent = fullBlock
			.replace(/"/g, '\\"')
			.replace(/
?
/g, '\\A '); 

		// Attach 'after' decoration to the start of the replacement range
		// (Actually, attaching to the end of the first line is safer for 'after')
		const anchorLine = range.start.line;
		const anchorPos = new vscode.Position(anchorLine, Number.MAX_VALUE);
		const margin = getDynamicMargin(editor, anchorLine, fullBlock);

		decorationReplaceBlockType = vscode.window.createTextEditorDecorationType({
			after: {
				contentText: '', // Handled by CSS content
				color: new vscode.ThemeColor('charts.purple'),
				backgroundColor: new vscode.ThemeColor('editor.background'),
				fontStyle: 'italic',
				fontWeight: '600',
				margin: `0 0 0 ${margin}`,
				textDecoration: `none; display: inline-block; white-space: pre; content: "${cssContent}"; border: 1px solid var(--vscode-charts-purple); padding: 4px; border-radius: 4px; box-shadow: 0 4px 8px rgba(0,0,0,0.25); pointer-events: none; position: relative; z-index: 100; vertical-align: top;`
			}
		});
		editor.setDecorations(decorationReplaceBlockType, [{ range: new vscode.Range(anchorPos, anchorPos) }]);
	}

	previewVisible = true;
	vscode.commands.executeCommand('setContext', UI_CONTEXT_KEY, true);
	currentAction = action;
}

function hidePreviewUI(suppress?: boolean): void {
	disposePreviewDecorations();
	previewVisible = false;
	vscode.commands.executeCommand('setContext', UI_CONTEXT_KEY, false);
	if (suppress) {
		suppressAutoPreview = true;
	}
}

// -------------------- Hardcoded single-step actions --------------------
function getHardcodedNextAction(editor: vscode.TextEditor): PlannedAction | undefined {
	const cursor = editor.selection.active;
	const doc = editor.document;
	const lineCount = doc.lineCount;
	const clamp = (n: number, min: number, max: number) => Math.max(min, Math.min(max, n));

	// Step 0: Insert multiline content two lines below the cursor (start of target line)
	if (mockStep === 0) {
		const targetLine = clamp(cursor.line + 2, 0, Math.max(0, lineCount - 1));
		return {
			kind: 'editInsert',
			position: [targetLine, 0],
			text: '/* crowd-pilot: insert start */
line A
line B
/* crowd-pilot: insert end */
'
		};
	}
	// Step 1: Replace a two-line range three and four lines below the cursor
	if (mockStep === 1) {
		const startLine = clamp(cursor.line + 3, 0, Math.max(0, lineCount - 1));
		const endLine = clamp(startLine + 1, 0, Math.max(0, lineCount - 1));
		const endChar = doc.lineAt(endLine).range.end.character;
		const range = {
			start: [startLine, 0] as [number, number],
			end: [endLine, endChar] as [number, number]
		};
		const replacement = [
			'/* crowd-pilot: replacement */',
			'REPLACED LINE 1',
			'REPLACED LINE 2'
		].join('
');
		return { kind: 'editReplace', range, text: replacement };
	}
	// Step 2: Delete a three-line range six to eight lines below the cursor
	if (mockStep === 2) {
		const startLine = clamp(cursor.line + 6, 0, Math.max(0, lineCount - 1));
		const endLine = clamp(startLine + 2, 0, Math.max(0, lineCount - 1));
		
		// To fully delete the lines including the newline, we target the start of the next line.
		let endPosLine = endLine + 1;
		let endPosChar = 0;
		
		if (endPosLine >= lineCount) {
			// If deleting the last line(s), just go to the end of the document
			endPosLine = lineCount - 1;
			endPosChar = doc.lineAt(endPosLine).range.end.character;
		}

		const range = {
			start: [startLine, 0] as [number, number],
			end: [endPosLine, endPosChar] as [number, number]
		};
		return { kind: 'editDelete', range };
	}
	// Step 3: Execute in Terminal
	if (mockStep === 3) {
		return { kind: 'terminalSendText', text: 'echo "Hello World"' };
	}
	// Step 4: Move Cursor to End of File
	if (mockStep === 4) {
		const lastLine = doc.lineCount - 1;
		const lastChar = doc.lineAt(lastLine).range.end.character;
		return {
			kind: 'setSelections',
			selections: [{ start: [lastLine, lastChar], end: [lastLine, lastChar] }]
		};
	}
	return undefined;
}

function advanceMockStep(): void {
	mockStep = (mockStep + 1) % 5;
}

async function autoShowNextAction(): Promise<void> {
	if (suppressAutoPreview) { return; }
	const editor = vscode.window.activeTextEditor;
	if (!editor) { return; }
	try {
		const next = await requestModelActions(editor);
		if (next) {
			showPreviewUI(next);
		} else {
			hidePreviewUI();
		}
	} catch (err) {
		hidePreviewUI();
	}
}

// -------------------- SGLang Client (simple test) --------------------
async function callSGLangChat(): Promise<void> {
	const requestBody = {
		model: 'qwen/qwen2.5-0.5b-instruct',
		messages: [
			{ role: 'user', content: 'What is the capital of France?' }
		]
	};
	const postData = JSON.stringify(requestBody);

	const options = {
		hostname: HOSTNAME,
		port: PORT,
		path: '/v1/chat/completions',
		method: 'POST',
		headers: {
			'Content-Type': 'application/json',
			'Content-Length': Buffer.byteLength(postData)
		}
	};

	try {
		const json = await new Promise<any>((resolve, reject) => {
			const req = http.request(options, (res: http.IncomingMessage) => {
				let data = '';
				res.on('data', (chunk: Buffer) => {
					data += chunk.toString();
				});
				res.on('end', () => {
					try {
						resolve(JSON.parse(data));
					} catch (err) {
						reject(new Error(`Failed to parse response: ${err instanceof Error ? err.message : String(err)}`));
					}
				});
			});

			req.on('error', (err: Error) => {
				reject(err);
			});

			req.write(postData);
			req.end();
		});

		vscode.window.showInformationMessage(`SGLang response: ${JSON.stringify(json, null, 2)}`);
	} catch (err) {
		const errorMessage = err instanceof Error ? err.message : String(err);
		vscode.window.showErrorMessage(`SGLang request failed: ${errorMessage}`);
	}
}

// -------------------- Model-planned Actions --------------------
async function requestModelActions(editor: vscode.TextEditor): Promise<PlannedAction> {
	const schemaDescription = [
		'Role: You suggest the next VS Code editor/terminal action to progress the current task.',
		'Output ONLY a JSON object (no prose, no code fences).',
		'Coordinates are zero-based [line, column].',
		'Allowed actions (JSON schema-like):',
		'{ kind: "showTextDocument" }',
		'{ kind: "setSelections", selections: Array<{ start: [number, number], end: [number, number] }> }',
		'{ kind: "editInsert", position: [number, number], text: string }',
		'{ kind: "editDelete", range: { start: [number, number], end: [number, number] } }',
		'{ kind: "editReplace", range: { start: [number, number], end: [number, number] }, text: string }',
		'{ kind: "terminalShow" }',
		'{ kind: "terminalSendText", text: string }',
		'Guidelines:',
		'- If you you insert text, insert until the logical end of the current statement or block.',
		'- When inserting text, make sure to not repeat existing text (except when replacing existing text).',
		'- Use double-quoted JSON strings.'
	].join('
');

	const doc = editor.document;
	const cursor = editor.selection.active;
	const contextRange = new vscode.Range(new vscode.Position(0, 0), cursor);
	const contextCode = doc.getText(contextRange);
	const maxContextChars = 20000;
	const allLines = contextCode.split(/
?
/);
	let startLineIndex = 0;
	let visibleLines = allLines;
	if (contextCode.length > maxContextChars) {
		let acc = 0;
		let idx = allLines.length;
		while (idx > 0 && acc <= maxContextChars) {
			idx--;
			acc += allLines[idx].length + 1;
		}
		startLineIndex = idx;
		visibleLines = allLines.slice(idx);
	}
	const numberedContext = visibleLines.map((line, i) => `${startLineIndex + i}: ${line}`).join('
');

	const tabbingPrompt = [
		'Your role: Propose the single next action according to the schema to help the developer progress.',
		'',
		'Available context:',
		`- File: ${doc.fileName}`,
		`- Language: ${doc.languageId}`,
		`- Cursor: (${cursor.line}, ${cursor.character})`,
		'',
		'Current file content up to the cursor (zero-based line numbers):',
		'```',
		numberedContext,
		'```',
		'',
		'Respond with ONLY a JSON object containing exactly one action.'
	].join('
');

	const requestBody = {
		model: 'qwen/qwen2.5-0.5b-instruct',
		messages: [
			{ role: 'system', content: schemaDescription },
			{ role: 'user', content: tabbingPrompt }
		]
	};

	const postData = JSON.stringify(requestBody);
	const options = {
		hostname: HOSTNAME,
		port: PORT,
		path: '/v1/chat/completions',
		method: 'POST',
		headers: {
			'Content-Type': 'application/json',
			'Content-Length': Buffer.byteLength(postData)
		}
	};

	const json = await new Promise<any>((resolve, reject) => {
		const req = http.request(options, (res: http.IncomingMessage) => {
			let data = '';
			res.on('data', (chunk: Buffer) => { data += chunk.toString(); });
			res.on('end', () => {
				try {
					resolve(JSON.parse(data));
				} catch (err) {
					reject(new Error(`Failed to parse response: ${err instanceof Error ? err.message : String(err)}`));
				}
			});
		});
		req.on('error', (err: Error) => reject(err));
		req.write(postData);
		req.end();
	});

	const content = extractChatContent(json);
	if (typeof content !== 'string' || content.trim().length === 0) {
		throw new Error('Empty model content');
	}
	const action = parsePlannedAction(content);
	if (!action) {
		throw new Error('No valid action parsed from model output');
	}
	return action;
}

function extractChatContent(json: any): string | undefined {
	try {
		if (json && Array.isArray(json.choices) && json.choices[0]) {
			const choice = json.choices[0];
			if (choice.message && typeof choice.message.content === 'string') {
				return choice.message.content;
			}
			if (typeof choice.text === 'string') {
				return choice.text;
			}
		}
		return undefined;
	} catch {
		return undefined;
	}
}

function parsePlannedAction(raw: string): PlannedAction | undefined {
	let text = raw.trim();
	text = text.replace(/^```(?:json)?\s*/i, '').replace(/```\s*$/i, '').trim();
	let parsed: any;
	try {
		parsed = JSON.parse(text);
	} catch (err) {
		return undefined;
	}
	assert (!Array.isArray(parsed), 'Model must not output an array');
	switch (parsed.kind) {
		case 'showTextDocument':
			return { kind: 'showTextDocument' };
		case 'setSelections': {
			const selections = Array.isArray(parsed.selections) ? parsed.selections : [];
			const norm = selections.map((s: any) => ({
				start: Array.isArray(s?.start) && s.start.length === 2 ? [Number(s.start[0]) || 0, Number(s.start[1]) || 0] as [number, number] : [0, 0] as [number, number],
				end: Array.isArray(s?.end) && s.end.length === 2 ? [Number(s.end[0]) || 0, Number(s.end[1]) || 0] as [number, number] : [0, 0] as [number, number]
			}));
			return { kind: 'setSelections', selections: norm };
		}
		case 'editInsert': {
			const pos = Array.isArray(parsed.position) && parsed.position.length === 2 ? [Number(parsed.position[0]) || 0, Number(parsed.position[1]) || 0] as [number, number] : [0, 0] as [number, number];
			const textVal = typeof parsed.text === 'string' ? parsed.text : '';
			return { kind: 'editInsert', position: pos, text: textVal };
		}
		case 'editDelete': {
			const start = Array.isArray(parsed.range?.start) && parsed.range.start.length === 2 ? [Number(parsed.range.start[0]) || 0, Number(parsed.range.start[1]) || 0] as [number, number] : [0, 0] as [number, number];
			const end = Array.isArray(parsed.range?.end) && parsed.range.end.length === 2 ? [Number(parsed.range.end[0]) || 0, Number(parsed.range.end[1]) || 0] as [number, number] : [0, 0] as [number, number];
			return { kind: 'editDelete', range: { start, end } };
		}
		case 'editReplace': {
			const start = Array.isArray(parsed.range?.start) && parsed.range.start.length === 2 ? [Number(parsed.range.start[0]) || 0, Number(parsed.range.start[1]) || 0] as [number, number] : [0, 0] as [number, number];
			const end = Array.isArray(parsed.range?.end) && parsed.range.end.length === 2 ? [Number(parsed.range.end[0]) || 0, Number(parsed.range.end[1]) || 0] as [number, number] : [0, 0] as [number, number];
			const textVal = typeof parsed.text === 'string' ? parsed.text : '';
			return { kind: 'editReplace', range: { start, end }, text: textVal };
		}
		case 'terminalShow':
			return { kind: 'terminalShow' };
		case 'terminalSendText': {
			const textVal = typeof parsed.text === 'string' ? parsed.text : '';
			return { kind: 'terminalSendText', text: textVal };
		}
		default:
			return undefined;
	}
}