class ShellModule {
    constructor() {
        this.commands = {};
        this.terminal = null;
        this._vars = {
            HOME: '/',
            USER: 'darkbot',
            SHELL: 'webx11-shell',
            TERM: 'xterm-256color',
            PWD: '/'
        };
        this._scriptDepth = 0;
        this._maxScriptDepth = 3;
    }

    requirements() {
        return { met: true, missing: [] };
    }

    getHelpInfo() {
        return {
            'export': 'export <var>=<value> — Set a shell variable',
            'unset': 'unset <var> — Remove a shell variable',
            'script': 'script <path.sh> — Run a shell script from VFS',
            '$': '$ <command> — Execute with shell parsing (default: auto-detected)',
            'sh': 'sh <path.sh> — Run a shell script from VFS (alias for script)',
            'set': 'set — List all shell variables',
        };
    }

    registerCommands() {
        this.commands['export'] = (args) => this._cmdExport(args);
        this.commands['unset'] = (args) => this._cmdUnset(args);
        this.commands['script'] = (args) => this._cmdScript(args);
        this.commands['sh'] = (args) => this._cmdScript(args);
        this.commands['set'] = () => this._cmdSet();
    }

    // ── Hook into terminal.executeCommand ──

    init() {
        // Guard: prevent double-wrapping if init is called multiple times, and adopt the wrapper
        // if another instance already installed one (shell.js used to be loaded twice — once in
        // critical-ext-bundle.js, once from main.html's extension list — and the two copies could
        // disagree about their version).
        if (this._initialized) return;
        if (this.terminal && this.terminal._shellModule && this.terminal._shellModule !== this) {
            this._initialized = true;
            return;
        }
        this._initialized = true;
        
        // Wrap executeCommand to add shell parsing — only for compound commands
        const origExecute = this.terminal.executeCommand.bind(this.terminal);
        const self = this;
        this.terminal.executeCommand = async function(rawInput) {
            if (!rawInput.trim()) return;
            this.markDirty();
            this.printUserPrompt(rawInput);

            // Save to command history (preserved from original executeCommand)
            const cmdRaw = rawInput.trim();
            if (this.history.length === 0 || this.history[this.history.length - 1] !== cmdRaw) {
                this.history.push(cmdRaw);
            }
            if (this.history.length > this._historyCap) {
                this.history = this.history.slice(-this._historyCap);
            }
            this.historyIndex = this.history.length;
            this._saveCommandHistory();

            // For simple single-word commands without special chars, skip shell parsing
            if (/^[a-zA-Z0-9._\/-]+$/.test(rawInput.trim()) && !rawInput.includes(' ') && !rawInput.includes('$')) {
                try {
                    return await this.security.checkAndRun(rawInput);
                } catch(e) {
                    this.print('Error: ' + e.message, 'error');
                    return;
                }
            }

            // Substitute variables in the raw input
            const substituted = self._substituteVars(rawInput);
            // Split on ; first (sequence)
            const seqParts = self._splitSequence(substituted);
            for (const seqPart of seqParts) {
                if (!seqPart.trim()) continue;
                // Split on && and || — operator now attached to the FOLLOWING segment
                const chainParts = self._splitChain(seqPart.trim());
                let lastOk = true;
                for (const chainPart of chainParts) {
                    if (!chainPart.cmd.trim()) continue;
                    const { cmd: chainCmd, operator } = chainPart;
                    // Check the operator that PRECEDES this command
                    if (operator === '&&' && !lastOk) continue;
                    if (operator === '||' && lastOk) continue;
                    // Check for redirects
                    const redirectInfo = self._extractRedirects(chainCmd);
                    if (redirectInfo.hasRedirect) {
                        // Same capture-and-write path the script runner uses. _executeWithRedirect
                        // handed `>` to builtins, so `echo hi > /f` printed the operator instead of
                        // writing the file.
                        lastOk = await self._runCommand(chainCmd, { $: 0 }, { inScript: false });
                    } else {
                        // Normal or piped command
                        const pipeParts = this.splitPipe(chainCmd);
                        if (pipeParts.length > 1) {
                            await this.executePipeChain(pipeParts);
                        } else {
                            // Single command — check for shell built-ins first
                            // v4.6.132: quote-aware (split(/\s+/) broke `grep "a b" f; ls`)
                            const argv = self._tokenize(chainCmd);
                            if (!argv.length) continue;
                            const cmd = argv[0].toLowerCase();
                            // Globs expand at the prompt too — the script runner did it and the
                            // interactive path did not, so `ls *.txt` printed (empty) but the same
                            // line inside a script worked.
                            const args = self._expandGlobs(argv.slice(1), (this.fs && this.fs.currentPath) || []);
                            const expandedCmd = [cmd].concat(args).join(' ');
                            if (self.commands[cmd]) {
                                try {
                                    this.markDirty();
                                    await self.commands[cmd](args);
                                    lastOk = true;
                                } catch(e) {
                                    this.print('Error: ' + e.message, 'error');
                                    lastOk = false;
                                }
                            } else {
                                try {
                                    await this.security.checkAndRun(expandedCmd);
                                    lastOk = true;
                                } catch(e) {
                                    this.print('Error: ' + e.message, 'error');
                                    lastOk = false;
                                }
                            }
                        }
                    }
                }
            }
        };
        this.terminal._shellModule = this;

        // Modify pipe chain to add pipe-aware injection and security checks
        const origPipeChain = this.terminal.executePipeChain.bind(this.terminal);
        this.terminal.executePipeChain = async function(pipeParts) {
            // Write pipe input from previous segment as temp file for next segment
            const shellMod = this._shellModule;
            let pipeInput = null;
            for (let i = 0; i < pipeParts.length; i++) {
                const cmdText = pipeParts[i];
                // v4.6.132: quote-aware tokenisation. split(/\s+/) turned `grep "a b" f | wc -l`
                // into args ['"a','b"','f'], and `cmd | | cmd2` into a stage with cmd '' that was
                // still dispatched. The security tokeniser keeps a quoted argument whole and
                // returns [] for an empty stage, so the guard below can skip it.
                const argv = this.security._parseArgs(String(cmdText || '').trim());
                if (argv.length === 0) continue;
                const cmd = argv[0].toLowerCase();
                let args = argv.slice(1);

                // Security gate — replicate the original executePipeChain checks
                const cls = this.security._classify(cmdText);
                if (cls.destructive && this.security.level > 0) {
                    this.print(`⚠️ Security: Destructive command "${cmd}" blocked in pipe at level ${this.security.level}`, 'error');
                    return;
                }
                if (cls.system && this.security.level > 0) {
                    this.print(`⚠️ Security: System command "${cmd}" blocked in pipe at level ${this.security.level}`, 'error');
                    return;
                }
                if (!cls.known && this.security.level >= 2) {
                    this.print(`⚠️ Security: Unknown command "${cmd}" blocked in pipe (paranoid mode)`, 'error');
                    return;
                }

                this._pipeInput = pipeInput;

                if (pipeInput !== null) {
                    // Write pipe input as temp file so file-reading commands can use it
                    this.fs.writeFile('__pipebuf__', pipeInput);
                    // Inject __pipebuf__ as file arg if command is pipe-aware (reads files for input)
                    if (shellMod && shellMod._isPipeAware(cmd)) {
                        // Don't inject if command already has enough file args
                        if (!args.some(a => !a.startsWith('-') && a !== '|' && a !== '>')) {
                            args = args.concat('__pipebuf__');
                        }
                    }
                }

                try {
                    if (i < pipeParts.length - 1) {
                        // v4.6.131: hand the stage's own text to the command (this override is the
                        // one that actually runs — it replaces terminal.executePipeChain), so
                        // `js "a b".length | wc -c` keeps its quotes like a bare command does.
                        pipeInput = await this.capturePipeOutput(cmd, args, cmdText);
                    } else {
                        await this.dispatchCommand(cmd, args, cmdText);
                    }
                } finally {
                    // Clean up temp file
                    if (this.fs.readFile('__pipebuf__') !== null) {
                        delete this.fs.root.content['__pipebuf__'];
                    }
                }
            }
            this._pipeInput = null;
        };
    }

    // ── Tokenizer helpers ──

    /**
     * Split a command line into argv, honouring quotes — the same parser the dispatcher uses
     * (`security._parseArgs`), so the shell paths and the bare-command path cannot drift.
     * v4.6.132: every `.split(/\s+/)` call site in this file turned a quoted argument into several,
     * and dispatched an empty stage as a command named ''.
     */
    _tokenize(cmdText) {
        const src = String(cmdText || '').trim();
        if (!src) return [];
        const sec = (this.terminal && this.terminal.security) || this.security;
        if (sec && typeof sec._parseArgs === 'function') return sec._parseArgs(src);
        return src.split(/\s+/);   // defensive: the terminal always exposes security
    }

    _splitSequence(input) {
        // Split on ; (not inside quotes)
        const parts = [];
        let current = '';
        let inQuote = false;
        let quoteChar = '';
        for (const ch of input) {
            if ((ch === '"' || ch === "'") && !inQuote) {
                inQuote = true; quoteChar = ch; current += ch;
            } else if (ch === quoteChar && inQuote) {
                inQuote = false; quoteChar = ''; current += ch;
            } else if (ch === ';' && !inQuote) {
                parts.push(current.trim());
                current = '';
            } else {
                current += ch;
            }
        }
        parts.push(current.trim());
        return parts;
    }

    _splitChain(input) {
        // Split on && and ||, preserving operator info
        // Operator is attached to the FOLLOWING segment (the one it guards)
        const parts = [];
        let current = '';
        let inQuote = false;
        let quoteChar = '';
        let pendingOp = null;  // operator from previous split, applies to next segment
        let i = 0;
        while (i < input.length) {
            const ch = input[i];
            if ((ch === '"' || ch === "'") && !inQuote) {
                inQuote = true; quoteChar = ch; current += ch; i++;
            } else if (ch === quoteChar && inQuote) {
                inQuote = false; quoteChar = ''; current += ch; i++;
            } else if (!inQuote && input.substring(i, i+2) === '&&') {
                parts.push({ cmd: current.trim(), operator: pendingOp });
                pendingOp = '&&';
                current = ''; i += 2;
            } else if (!inQuote && input.substring(i, i+2) === '||') {
                parts.push({ cmd: current.trim(), operator: pendingOp });
                pendingOp = '||';
                current = ''; i += 2;
            } else {
                current += ch; i++;
            }
        }
        parts.push({ cmd: current.trim(), operator: pendingOp });
        return parts;
    }

    _extractRedirects(input) {
        // Find >, >>, < outside quotes
        let cmd = '';
        let hasRedirect = false;
        let redirectOp = '';
        let redirectFile = '';
        let append = false;
        let inQuote = false, quoteChar = '';
        let i = 0;
        const parts = [];
        let current = '';
        while (i < input.length) {
            const ch = input[i];
            if ((ch === '"' || ch === "'") && !inQuote) {
                inQuote = true; quoteChar = ch; current += ch; i++;
            } else if (ch === quoteChar && inQuote) {
                inQuote = false; quoteChar = ''; current += ch; i++;
            } else if (!inQuote) {
                if (input.substring(i, i+2) === '>>') {
                    if (current.trim()) { parts.push(current.trim()); current = ''; }
                    hasRedirect = true;
                    redirectOp = '>>';
                    append = true;
                    i += 2;
                    // Read until next redirect or end
                    let file = '';
                    while (i < input.length && input[i] === ' ') i++;
                    while (i < input.length && input[i] !== '>' && input[i] !== '<' && input[i] !== '|') {
                        file += input[i]; i++;
                    }
                    redirectFile = file.trim();
                    if (i < input.length && (input[i] === '>' || input[i] === '<')) continue;
                    break;
                } else if (input.substring(i, i+1) === '>') {
                    if (current.trim()) { parts.push(current.trim()); current = ''; }
                    hasRedirect = true;
                    redirectOp = '>';
                    append = false;
                    i += 1;
                    let file = '';
                    while (i < input.length && input[i] === ' ') i++;
                    while (i < input.length && input[i] !== '>' && input[i] !== '<' && input[i] !== '|') {
                        file += input[i]; i++;
                    }
                    redirectFile = file.trim();
                    if (i < input.length && (input[i] === '>' || input[i] === '<')) continue;
                    break;
                } else if (input.substring(i, i+1) === '<') {
                    if (current.trim()) { parts.push(current.trim()); current = ''; }
                    hasRedirect = true;
                    redirectOp = '<';
                    i += 1;
                    let file = '';
                    while (i < input.length && input[i] === ' ') i++;
                    while (i < input.length && input[i] !== '>' && input[i] !== '<' && input[i] !== '|') {
                        file += input[i]; i++;
                    }
                    redirectFile = file.trim();
                    if (i < input.length && (input[i] === '>' || input[i] === '<')) continue;
                    break;
                } else {
                    current += ch; i++;
                }
            } else {
                current += ch; i++;
            }
        }
        if (current.trim()) parts.push(current.trim());

        const cmdText = parts.join(' ');
        return {
            hasRedirect,
            redirectOp,
            redirectFile,
            append,
            cmdText,
            exitOk: true
        };
    }

    async _executeWithRedirect(redirectInfo) {
        const { redirectOp, redirectFile, append, cmdText } = redirectInfo;
        const fs = this.terminal.fs;

        if (redirectOp === '<') {
            // Read file content as stdin
            const inputContent = fs.readFile(redirectFile);
            if (inputContent === null) {
                this.terminal.print(`shell: ${redirectFile}: No such file`, 'error');
                redirectInfo.exitOk = false;
                return;
            }
            this.terminal._pipeInput = inputContent;
            try {
                // v4.6.132: quote-aware — `cat < "/my file.txt"` and `grep "a b" f < x` lost the
                // quoted argument to split(/\s+/).
                const argv = this._tokenize(cmdText);
                const cmd = (argv[0] || '').toLowerCase();
                const args = argv.slice(1);
                // If command reads files, inject pipe content as temp file
                if (this._isPipeAware(cmd)) {
                    fs.writeFile('__pipebuf__', inputContent);
                    const newArgs = [...args];
                    if (!newArgs.some(a => !a.startsWith('-'))) {
                        newArgs.push('__pipebuf__');
                    }
                    try {
                        await this.terminal.dispatchCommand(cmd, newArgs);
                    } finally {
                        if (fs.readFile('__pipebuf__') !== null) {
                            delete fs.root.content['__pipebuf__'];
                        }
                    }
                } else {
                    await this.terminal.dispatchCommand(cmd, args);
                }
                redirectInfo.exitOk = true;
            } catch(e) {
                this.terminal.print('Error: ' + e.message, 'error');
                redirectInfo.exitOk = false;
            } finally {
                this.terminal._pipeInput = null;
            }
            return;
        }

        // > or >> — capture output, write to file
        let output = '';
        this.terminal._pushPrintCapture(buf => { output += buf; });
        let cmdOk = true;

        try {
            // Check for pipes within the command before redirect
            const pipeParts = this.terminal.splitPipe(cmdText);
            if (pipeParts.length > 1) {
                // Execute pipe chain manually to capture all output
                let pipeInput = null;
                for (let i = 0; i < pipeParts.length; i++) {
                    const pText = pipeParts[i];
                    // v4.6.132: tokenise like the interactive path (and keep the raw text, so a
                    // `js` stage in a script keeps its string literals too).
                    const pArgv = this._tokenize(pText);
                    if (!pArgv.length) continue;
                    const pCmd = pArgv[0].toLowerCase();
                    const pArgs = pArgv.slice(1);
                    if (pipeInput !== null) {
                        fs.writeFile('__pipebuf__', pipeInput);
                    }
                    if (i < pipeParts.length - 1) {
                        let capt = '';
                        this.terminal._pushPrintCapture(buf => { capt += buf; });
                        try {
                            await this.terminal.dispatchCommand(pCmd, pArgs, pText);
                        } finally {
                            this.terminal._popPrintCapture();
                        }
                        pipeInput = capt.trim();
                    } else {
                        await this.terminal.dispatchCommand(pCmd, pArgs, pText);
                    }
                    if (fs.readFile('__pipebuf__') !== null) {
                        delete fs.root.content['__pipebuf__'];
                    }
                }
            } else {
                // v4.6.132: quote-aware, and pass the raw text so `js`/`node -e` keep literals here too
                const argv = this._tokenize(cmdText);
                const cmd = (argv[0] || '').toLowerCase();
                const args = argv.slice(1);
                await this.terminal.dispatchCommand(cmd, args, cmdText);
            }
        } catch(e) {
            cmdOk = false;
            // Pop capture before showing the error
            this.terminal._popPrintCapture();
            this.terminal.print('Error: ' + e.message, 'error');
            redirectInfo.exitOk = false;
            return;
        } finally {
            // Always pop capture — critical: without this, terminal output stays captured
            // (empty stack = normal DOM printing, so pop is idempotent-safe when already popped)
            if (this.terminal._printCaptureStack && this.terminal._printCaptureStack.length > 0) {
                // popped in catch path for error case; success path pops here
                this.terminal._popPrintCapture();
            }
        }

        const captured = output.trimEnd();

        if (captured) {
            if (append) {
                const existing = fs.readFile(redirectFile) || '';
                fs.writeFile(redirectFile, existing + (existing ? '\n' : '') + captured);
            } else {
                fs.writeFile(redirectFile, captured);
            }
            this.terminal.print(`Redirected ${captured.split('\n').length} line(s) to ${redirectFile}`, 'success');
        } else {
            // Write empty file
            if (!append) {
                fs.writeFile(redirectFile, '');
                this.terminal.print(`Redirected (empty) to ${redirectFile}`, 'success');
            }
        }
        redirectInfo.exitOk = cmdOk;
    }

    _isPipeAware(cmd) {
        // Commands that read from files and should use the pipe buffer file. wc is NOT here any
        // more: it reads terminal._pipeInput natively (v4.6.111), and injecting __pipebuf__ gave
        // `3 __pipebuf__` instead of a bare count.
        // grep/head/tail/wc read terminal._pipeInput themselves (v4.6.111-116). Injecting the
        // __pipebuf__ file for them made `cat f | grep x` match twice (the pipe buffer AND the cwd
        // file of the same name) and printed "3 __pipebuf__" from wc.
        return ['sort', 'cut', 'uniq', 'expand'].includes(cmd);
    }

    // ── Variable substitution ──

    _substituteVars(input) {
        // Replace $VAR and ${VAR} (not inside single quotes)
        let result = '';
        let inSingle = false;
        let i = 0;
        while (i < input.length) {
            const ch = input[i];
            if (ch === "'") {
                inSingle = !inSingle;
                result += ch;
                i++;
            } else if (ch === '$' && !inSingle && i + 1 < input.length) {
                // Check for $(
                if (input[i+1] === '(') {
                    result += ch;
                    i++;
                    continue;
                }
                // Check for ${VAR}
                if (input[i+1] === '{') {
                    let end = input.indexOf('}', i);
                    if (end !== -1) {
                        const varName = input.substring(i+2, end);
                        const val = this._getVar(varName);
                        result += val !== undefined ? val : '$' + varName;
                        i = end + 1;
                        continue;
                    }
                }
                // Check for $VAR (alphanumeric/underscore)
                let j = i + 1;
                if (j < input.length && /[A-Za-z_]/.test(input[j])) {
                    while (j < input.length && /\w/.test(input[j])) j++;
                    const varName = input.substring(i+1, j);
                    const val = this._getVar(varName);
                    result += val !== undefined ? val : '';
                    i = j;
                    continue;
                }
                // $ followed by digit — not a var
                result += ch;
                i++;
            } else {
                result += ch;
                i++;
            }
        }
        return result;
    }

    _getVar(name) {
        if (name === 'PWD') return '/' + this.terminal.fs.currentPath.join('/');
        return this._vars[name] !== undefined ? this._vars[name] : undefined;
    }

    _setVar(name, value) {
        this._vars[name] = value;
    }

    // ── Commands ──

    _cmdExport(args) {
        if (!args[0] || !args[0].includes('=')) {
            return this.terminal.print('Usage: export <var>=<value>', 'warning');
        }
        const eqIdx = args[0].indexOf('=');
        const name = args[0].substring(0, eqIdx);
        let value = args[0].substring(eqIdx + 1);
        // Support quoted values: export FOO="hello world"
        if (args.length > 1) {
            const rest = args.slice(1).join(' ');
            if (value.endsWith('"') || value.endsWith("'")) {
                // First part ended quote — fine
            } else if (value.startsWith('"') || value.startsWith("'")) {
                value = value + (rest ? ' ' + rest : '');
            }
        }
        // Strip surrounding quotes
        if ((value.startsWith('"') && value.endsWith('"')) ||
            (value.startsWith("'") && value.endsWith("'"))) {
            value = value.substring(1, value.length - 1);
        }
        this._setVar(name, value);
        this.terminal.print(`Shell ${name}=${value}`, 'success');
    }

    _cmdUnset(args) {
        if (!args[0]) return this.terminal.print('Usage: unset <var>', 'warning');
        delete this._vars[args[0]];
        this.terminal.print(`Shell var removed: ${args[0]}`, 'info');
    }

    _cmdSet() {
        const fs = this.terminal.fs;
        this.terminal.print('Shell variables:', 'info');
        for (const [k, v] of Object.entries(this._vars)) {
            this.terminal.print(`${k}=${v}`, 'info');
        }
        this.terminal.print(`PWD=/${fs.currentPath.join('/')}`, 'info');
    }

    async _cmdScript(args) {
        if (!args[0]) return this.terminal.print('Usage: script <path.sh>', 'warning');
        if (this._scriptDepth >= this._maxScriptDepth) {
            return this.terminal.print(`script: max recursion depth (${this._maxScriptDepth}) reached`, 'error');
        }
        const path = args[0];
        const content = this.terminal.fs.readFile(path);
        if (content === null) return this.terminal.print(`script: ${path}: No such file`, 'error');
        this._scriptDepth++;
        try {
            this.terminal.print(`Running script: ${path}`, 'info');
            const env = Object.assign({ $: 0 }, this._scriptEnv || {});
            this._inScript = true;
            let result = { ran: 0 };
            try {
                const tree = this._parseBlocks(content.split('\n'));
                result = await this._runInstructions(tree, env, { path, inScript: true });
            } catch (e) {
                // A parse error (unclosed block, bad for-header) must read as a script error, not
                // as a crashed terminal.
                this.terminal.print(`Script ${path} failed: ${e.message}`, 'error');
                result = { ran: 0 };
            } finally {
                this._inScript = false;
            }
            this._scriptEnv = env;
            this.terminal.print(`Script ${path} completed (${result.ran} statements, exit ${env.$})`, 'success');
        } finally {
            // Always decrement — even on error or thrown exception
            this._scriptDepth--;
        }
    }
    // Parse a script into an instruction tree. Line-by-line execution cannot express a loop body,
    // which is why `for … done` used to be fed to the AI one line at a time.
    _parseBlocks(lines) {
        const root = { body: [] };
        const stack = [root];
        const cur = () => stack[stack.length - 1];
        const push = (node) => {
            const top = cur();
            if (top.op === 'if') { (top.inElse ? top.else : top.then).push(node); }
            else { top.body.push(node); }
        };
        // `if [ -f /x ]; then echo y; fi` on one line is common enough to support: split atoms on
        // ';' when the line carries a block keyword, and keep quoted text intact otherwise.
        const atoms = [];
        lines.forEach((raw) => {
            const l = String(raw).replace(/\r$/, '');
            if (l.includes(';') && /\b(then|do|done|fi|else)\b/.test(l)) l.split(';').forEach(p => atoms.push(p));
            else atoms.push(l);
        });
        atoms.forEach((raw, idx) => {
            const line = String(raw).replace(/\r$/, '').trim();
            const lineNo = idx + 1;
            if (!line || line.startsWith('#')) return;
            const head = line.split(/\s+/)[0];
            if (head === 'for') {
                const m = line.match(/^for\s+([A-Za-z_][A-Za-z0-9_]*)\s+in\s+(.*)$/);
                if (!m) throw new Error('line ' + lineNo + ": expected 'for <var> in <items>'");
                const node = { op: 'for', line: lineNo, var: m[1], items: m[2].trim().split(/\s+/).filter(Boolean), body: [] };
                push(node); stack.push(node); return;
            }
            if (head === 'while') {
                const node = { op: 'while', line: lineNo, test: line.slice(5).trim(), body: [] };
                push(node); stack.push(node); return;
            }
            if (head === 'if') {
                const node = { op: 'if', line: lineNo, test: line.slice(2).trim(), then: [], else: [], inElse: false };
                push(node); stack.push(node); return;
            }
            if (head === 'then' || head === 'do') {
                // `then echo y` on the same atom still means "run echo y"
                const rest = line.slice(head.length).trim();
                if (rest) push({ op: 'simple', line: lineNo, text: rest });
                return;
            }
            if (head === 'else') {
                const top = cur();
                if (top.op !== 'if') throw new Error('line ' + lineNo + ": 'else' without 'if'");
                top.inElse = true;
                const rest = line.slice(4).trim();
                if (rest) push({ op: 'simple', line: lineNo, text: rest });
                return;
            }
            if (head === 'done' || head === 'fi') {
                const top = stack.pop();
                const want = !top ? null : (top.op === 'if' ? 'fi' : 'done');
                if (!want) throw new Error('line ' + lineNo + ": '" + head + "' without an open block");
                if (head !== want) throw new Error('line ' + lineNo + ": expected '" + want + "' to close '" + top.op + "' from line " + top.line);
                return;
            }
            push({ op: 'simple', line: lineNo, text: line });
        });
        if (stack.length !== 1) {
            const open = stack[stack.length - 1];
            throw new Error("unclosed '" + open.op + "' from line " + open.line + " — expected '" + (open.op === 'if' ? 'fi' : 'done') + "'");
        }
        const fix = (nodes) => nodes.map(n => {
            if (n.op === 'if') { n.body = n.then; n.elseBody = n.else; }
            if (n.body && (n.op === 'for' || n.op === 'while')) fix(n.body);
            if (n.body && n.op === 'if') fix(n.body);
            if (n.elseBody) fix(n.elseBody);
            return n;
        });
        return fix(root.body);
    }

    // Same rules as _substituteVars, but against an explicit env so a loop body sees `$i`, and
    // `$?` carries the previous statement's exit status.
    _expandVars(input, env) {
        const src = String(input);
        let out = '', inSingle = false, inDouble = false;
        for (let i = 0; i < src.length; i++) {
            const ch = src[i];
            if (ch === "'" && !inDouble) { inSingle = !inSingle; out += ch; continue; }
            if (ch === '"' && !inSingle) { inDouble = !inDouble; out += ch; continue; }
            if (ch !== '$' || inSingle) { out += ch; continue; }
            const next = src[i + 1];
            if (next === '?') { out += String(env.$ == null ? 0 : env.$); i++; continue; }
            let name = '';
            if (next === '{') {
                const end = src.indexOf('}', i + 2);
                if (end === -1) { out += ch; continue; }
                name = src.slice(i + 2, end); i = end;
            } else {
                const m = /^[A-Za-z_][A-Za-z0-9_]*/.exec(src.slice(i + 1));
                if (!m) { out += ch; continue; }
                name = m[0]; i += name.length;
            }
            out += (env[name] == null ? '' : String(env[name]));
        }
        return out;
    }

    // Wildcards only expand for unquoted arguments, and only against the VFS — `ls *.txt` used to
    // return an empty list because the literal pattern was handed to ls.
    _expandGlobs(args, cwdSegments) {
        const globToRe = (pat) => new RegExp('^' + pat.replace(/[.+^${}()|[\]\\]/g, '\\$&')
            .replace(/\*/g, '[^/]*').replace(/\?/g, '[^/]') + '$');
        const dirOf = (p) => {
            const segs = String(p).split('/').filter(Boolean);
            segs.pop();
            return segs;
        };
        return args.flatMap((arg) => {
            const a = String(arg);
            if (/^['"]/.test(a) || !/[*?]/.test(a)) return [a];
            const segs = a.split('/').filter(Boolean);
            const namePat = segs.pop() || '*';
            const rawDir = a.startsWith('/') ? segs : cwdSegments.concat(segs);
            // cwd segments may arrive as ['work'] or ['/work'] — normalise both
            const dirPath = '/' + rawDir.map(s => String(s).split('/').filter(Boolean).join('/'))
                .filter(Boolean).join('/');
            let entries = [];
            try {
                const fsv = this.terminal.fs;
                // ls() is the canonical lister; readDir() is the fallback so the helper also works
                // against a bare fake fs (and against any future module that only implements one).
                entries = (fsv && (fsv.ls ? fsv.ls(dirPath) : null)) || (fsv && fsv.readDir ? fsv.readDir(dirPath) : null) || [];
            } catch (e) { entries = []; }
            const re = globToRe(namePat);
            const hits = entries.filter(e => re.test(e.name)).map(e => (dirPath === '/' ? '' : dirPath) + '/' + e.name);
            return hits.length ? hits : [a];
        });
    }


    // Evaluate the only condition syntaxes the runner supports: test -f/-d/-e/-z/-n, `a = b`,
    // and the bracket spelling of the same. Anything else is false, never a crash.
    _evalTest(expr, env) {
        const t = this._expandVars(String(expr == null ? '' : expr), env || {})
            .trim()
            .replace(/^\[\s*/, '')      // `[ -f x ]`
            .replace(/\s*\]$/, '')
            .replace(/^test\s+/, '')     // `test -f x` — without this every `if test` was false
            .trim();
        if (!t) return false;
        const fs = this.terminal.fs;
        // v4.6.132: quote-aware — `[ -f "/my file.txt" ]` was false because the path was split.
        const parts = this._tokenize(t);
        const p = parts[1];
        switch (parts[0]) {
            case '-f': return typeof fs.readFile(p) === 'string';
            case '-d': return !!fs.readDir(p);
            case '-e': return typeof fs.readFile(p) === 'string' || !!fs.readDir(p);
            case '-z': return !p;
            case '-n': return !!p;
            case '!': return !this._evalTest(parts.slice(1).join(' '), env);
        }
        if (parts.length === 3 && (parts[1] === '=' || parts[1] === '==')) return parts[0] === parts[2];
        if (parts.length === 3 && parts[1] === '!=') return parts[0] !== parts[2];
        return false;
    }

    async _runInstructions(nodes, env, ctx) {
        let ran = 0;
        for (const node of nodes) {
            if (node.op === 'for') {
                for (const rawItem of node.items) {
                    const expanded = this._expandVars(rawItem, env);
                    // `for f in /work/*.txt` used to run ONCE with $f set to the literal pattern,
                    // because only command arguments went through glob expansion.
                    const cwd = (this.terminal.fs && this.terminal.fs.currentPath) || [];
                    const items = this._expandGlobs([expanded], cwd);
                    for (const item of items) {
                        env[node.var] = item;
                        const r = await this._runInstructions(node.body, env, ctx);
                        ran += r.ran + 1;
                    }
                }
                continue;
            }
            if (node.op === 'while') {
                let guard = 0;
                const cap = this._maxLoopIterations || 1000;
                while (guard++ < cap && this._evalTest(node.test, env)) {
                    const r = await this._runInstructions(node.body, env, ctx);
                    ran += r.ran + 1;
                }
                if (guard > cap) this.terminal.print('script: while loop hit the iteration limit (' + cap + ')', 'warning');
                continue;
            }
            if (node.op === 'if') {
                const take = this._evalTest(node.test, env);
                env.$ = take ? 0 : 1;
                const r = await this._runInstructions(take ? node.body : (node.elseBody || []), env, ctx);
                ran += r.ran + 1;
                continue;
            }
            const r = await this._runSimple(this._expandVars(node.text, env), env, Object.assign({}, ctx, { line: node.line }));
            ran += r.ran;
        }
        return { ran };
    }

    async _runSimple(text, env, ctx) {
        const seqParts = this._splitSequence(text);
        let lastOk = true;
        for (const seqPart of seqParts) {
            if (!seqPart.trim()) continue;
            lastOk = true;
            for (const chainPart of this._splitChain(seqPart.trim())) {
                if (!chainPart.cmd.trim()) continue;
                if (chainPart.operator === '&&' && !lastOk) continue;
                if (chainPart.operator === '||' && lastOk) continue;
                lastOk = await this._runCommand(chainPart.cmd, env, ctx);
            }
        }
        env.$ = lastOk ? 0 : 1;
        return { ran: 1, ok: lastOk };
    }

    async _runCommand(cmdText, env, ctx) {
        const redirectInfo = this._extractRedirects(cmdText);
        if (redirectInfo.hasRedirect) {
            const cap = { output: '', onChunk: null };
            const stack = this.terminal._printCaptureStack || (this.terminal._printCaptureStack = []);
            stack.push(cap);
            let ok = true;
            try { ok = await this._runCommand(redirectInfo.cmdText, env, ctx); }
            catch (e) { this.terminal.print('Error: ' + e.message, 'error'); ok = false; }
            finally { stack.pop(); }
            const target = redirectInfo.redirectFile;
            const prev = redirectInfo.append ? (this.terminal.fs.readFile(target) || '') : '';
            const wrote = this.terminal.fs.writeFile(target, prev + cap.output);
            if (!wrote) { this.terminal.print('script: cannot write ' + target, 'error'); return false; }
            return ok;
        }
        const pipeParts = this.terminal.splitPipe ? this.terminal.splitPipe(cmdText) : [cmdText];
        if (pipeParts.length > 1) {
            await this.terminal.executePipeChain(pipeParts);
            return true;
        }
        return this._dispatchOne(cmdText, env, ctx);
    }

    async _dispatchOne(cmdText, env, ctx) {
        // v4.6.132: quote-aware tokenisation (split(/\s+/) split `grep "a b" f` into three args)
        const argv = this._tokenize(cmdText);
        const cmd = (argv[0] || '').toLowerCase();
        const cwd = (this.terminal.fs && this.terminal.fs.currentPath) || [];
        const args = this._expandGlobs(argv.slice(1), cwd);
        if (this.commands[cmd]) {
            try { this.terminal.markDirty(); await this.commands[cmd](args); return true; }
            catch (e) { this.terminal.print('Error: ' + e.message, 'error'); return false; }
        }
        const known = (this.terminal.moduleManager && this.terminal.moduleManager.getAllCommands
            ? this.terminal.moduleManager.getAllCommands() : {})[cmd];
        if (ctx && ctx.inScript && !known) {
            // A script must never answer an unknown command by calling the AI.
            this.terminal.print('script:' + ctx.path + ':' + (ctx.line || '?') + ': ' + cmd + ': command not found', 'error');
            return false;
        }
        // Dispatch the EXPANDED argument list — passing cmdText here silently dropped the glob
        // results, so `ls /g*.txt` still reached the fs as a literal pattern.
        const rebuilt = [cmd].concat(args).join(' ');
        try { await this.terminal.security.checkAndRun(rebuilt); return true; }
        catch (e) { this.terminal.print('Error: ' + e.message, 'error'); return false; }
    }

}
if (typeof window.webx11 !== 'undefined' && window.webx11) {
    // Register with a cache-busting query: an unversioned URL let the browser keep serving a
    // pre-v4.6.111 shell.js after the bundle had already shipped the new runner.
    const _mm = window.webx11.moduleManager;
    const _ver = (_mm && (_mm.LATEST_VER || _mm.latestVer)) || ('t' + Date.now());
    const _inst = new ShellModule();
    webx11.moduleManager.registerModule(_inst,
        'https://webx11.duckdns.org/spaces/newos4/modules/ext/shell.js?v=' + _ver);
    // registerModule() does not call init(); only loadModule() does. A module registered from the
    // boot bundle therefore never installed its executeCommand wrapper, so prompt-level globbing
    // and redirects silently did nothing. Init it here, once.
    if (typeof _inst.init === 'function' && !_inst._initialized) {
        try { _inst.init(); } catch (e) { console.warn('ShellModule init failed:', e && e.message); }
    }
}