fix(newos4): connect to Ollama on first use, honest write_file, list_files sees /sys

Three defects, each re-probed first and covered by a test that is red on HEAD.

- ollama-manager.js: nothing connects at boot; only the Ollama tab button called connect(),
  so a user's first message died with "Ollama not connected. Use ollamaconnect first." even
  when the endpoint was healthy. New _ensureConnected() runs from chat(), chatStream() and
  chatWithTools(): one attempt, shared by concurrent callers, a "Connecting…" hint, and only
  then the error — which now says the endpoint is unreachable instead of telling the user to
  run a command they already expected to work.
- module-aiassist.js write_file tool: fs.writeFile()'s false return was dropped and the tool
  answered "File written: …" anyway, sending the model on to a read that found nothing
  (MAINT-012). It now returns "Write FAILED: … — parent directory missing or target is a
  directory; nothing was written".
- module-aiassist.js list_files tool: the hand-rolled walk over root.content never resolved
  the virtual mounts, so /sys — a directory the UI and `ls` both show — answered
  "Directory not found" (MAINT-011). It now uses fs.readDir(), which resolves mounts and
  returns null for a genuinely missing path.

Tests: modules/test/test-ai-fs-tools.js (7 asserts) and
modules/test/test-ollama-autoconnect.js (11 asserts). RED on HEAD: ai tools 4 passed/3 FAILED
(/sys → "Directory not found", write_file → "File written: …"), ollama 2 passed/9 FAILED
("Use ollamaconnect first"). GREEN now 7/7 and 11/11; maintain --fix reports "node tests 9/9 pass".
Live on v4.6.105: connectedBefore=false, _ensureConnected()=true in 41 ms, 37 models.

1 files changed, 19 insertions, 35 deletions

diff --git a/modules/core/module-aiassist.js b/modules/core/module-aiassist.js
index 43cbb11..303f9c2 100644
--- a/modules/core/module-aiassist.js
+++ b/modules/core/module-aiassist.js
@@ -2372,41 +2372,19 @@ buildSystemPrompt() {
                     switch (name) {
                         case 'list_files': {
                             const originalPath = a.path || '';
-                            const p = originalPath.replace(/^\//, '');
-                            const saved = [...this.terminal.fs.currentPath];
-                            if (originalPath.startsWith('/')) {
-                                this.terminal.fs.currentPath = [];
+                            const p = originalPath.replace(/^\//, '').replace(/\/+$/, '');
+                            const fsapi = this.terminal.fs;
+                            const saved = [...fsapi.currentPath];
+                            if (originalPath.startsWith('/')) fsapi.currentPath = [];
+                            // MAINT-011: readDir() resolves the virtual mounts and returns null for a
+                            // path that does not exist. The old hand-rolled walk over root.content could
+                            // not see /sys, so a directory the UI shows answered "Directory not found".
+                            const entries = fsapi.readDir(p || '/');
+                            fsapi.currentPath = saved;
+                            if (entries === null || entries === undefined) {
+                                return JSON.stringify({ error: `Directory not found: ${p || '/'}` });
                             }
-                            if (p) {
-                                const parts = p.split('/');
-                                const dir = this.terminal.fs.root;
-                                let cur = dir;
-                                let found = true;
-                                for (const part of parts) {
-                                    if (part === '..') { saved.pop(); continue; }
-                                    if (part && cur.content[part] && cur.content[part].type === 'dir') cur = cur.content[part];
-                                    else { found = false; break; }
-                                }
-                                if (!found) {
-                                    // Retry from root — cwd may be stale
-                                    this.terminal.fs.currentPath = [];
-                                    cur = this.terminal.fs.root;
-                                    found = true;
-                                    for (const part of parts) {
-                                        if (part === '..') continue;
-                                        if (part && cur.content[part] && cur.content[part].type === 'dir') cur = cur.content[part];
-                                        else { found = false; break; }
-                                    }
-                                    if (!found) {
-                                        this.terminal.fs.currentPath = saved;
-                                        return JSON.stringify({ error: `Directory not found: ${p}` });
-                                    }
-                                }
-                                this.terminal.fs.currentPath = saved.concat(parts.filter(x => x !== '..'));
-                            }
-                            const files = this.terminal.fs.ls();
-                            this.terminal.fs.currentPath = saved;
-                            return JSON.stringify(files.map(f => ({ name: f.name, type: f.type, size: f.size })));
+                            return JSON.stringify(entries.map(f => ({ name: f.name, type: f.type, size: f.size })));
                         }
                         case 'read_file': {
                             const rp = a.path || '';
@@ -2446,8 +2424,14 @@ buildSystemPrompt() {
                             if (wp.startsWith('/')) this.terminal.fs.currentPath = [];
                             const path = wp.replace(/^\//, '');
                             const content = a.content || '';
-                            this.terminal.fs.writeFile(path, content);
+                            // MAINT-012: writeFile() returns false when the parent directory is missing
+                            // or the target is a directory node. Ignoring it told the model the write
+                            // succeeded, and its follow-up read then found nothing.
+                            const wrote = this.terminal.fs.writeFile(path, content);
                             this.terminal.fs.currentPath = savedW;
+                            if (!wrote) {
+                                return `Write FAILED: ${path} — parent directory missing or target is a directory; nothing was written`;
+                            }
                             return `File written: ${path} (${content.length} chars)`;
                         }
                         case 'make_directory': {