fix(tui): keep the sidebar open under the / command palette

sidebarAvailable grouped suggestionsActive() with the full-screen overlays
(setup, wizards, pickers), whose stated rationale is that they "take over the
chat column and render at full width". That is not true of the `/` palette:
suggestionOverlay draws it through centerRenderedBlock at
minInt(width, suggestionPaletteMaxWidth), a centred box capped at 76 cells
floating over the chat column.

Treating it as full-screen collapsed the whole layout on every `/`: the sidebar
disappeared, the plan panel dropped out of it and re-rendered inline above the
composer, and the transcript re-wrapped to full width -- a jarring reflow for a
popup, and worst mid-run with a live plan on screen.

It cannot overlap the sidebar either: twoColumnTranscriptView renders the
overlay with width = chatColumnWidth, so the palette is capped at
min(chatColumn, 76) and centred inside the chat column. Mouse hit-testing is
unaffected because sidebarLineAtMouse carries its own suggestionsActive() guard,
so clicks still reach the palette rather than the sidebar rows beneath it.

The genuinely full-width overlays keep suppressing the sidebar, pinned by the
new test alongside the palette case.

internal/tools/file_tools_test.go

@@ -829,61 +829,3 @@ func TestGlobSkipsWorkspaceExcludedDirectoriesAndBinaryFiles(t *testing.T) {
 		t.Fatalf("expected only keep.txt, got:\n%s", res.Output)
 	}
 }
-
-// A backwards range (end_line < start_line) is a caller-arithmetic slip, not a
-// fatal error: read_file recovers by reading just start_line and surfaces a note
-// explaining the adjustment, matching how an end_line past EOF is auto-clamped.
-// It must never hard-error the way it used to.
-func TestReadFileToolRecoversBackwardsRange(t *testing.T) {
-	root := t.TempDir()
-	writeTestFile(t, filepath.Join(root, "notes.txt"), "alpha\nbeta\ngamma\ndelta\nepsilon")
-
-	result := NewReadFileTool(root).Run(context.Background(), map[string]any{
-		"path":       "notes.txt",
-		"start_line": 3,
-		"end_line":   2, // backwards
-	})
-
-	if result.Status != StatusOK {
-		t.Fatalf("backwards range must recover, not error; got %s: %s", result.Status, result.Output)
-	}
-	if strings.Contains(result.Output, "must be greater than or equal to start_line") {
-		t.Fatalf("backwards range still hard-errors: %q", result.Output)
-	}
-	for _, want := range []string{
-		"end_line 2 was before start_line 3", // the note
-		"only line 3 was read",
-		"3 | gamma",
-	} {
-		if !strings.Contains(result.Output, want) {
-			t.Fatalf("expected %q in output, got %q", want, result.Output)
-		}
-	}
-	// It read exactly start_line, nothing adjacent.
-	if strings.Contains(result.Output, "beta") || strings.Contains(result.Output, "delta") {
-		t.Fatalf("recovery read the wrong lines: %q", result.Output)
-	}
-}
-
-// A valid range with end_line >= start_line is byte-for-byte unchanged: the
-// recovery path must not touch normal reads (no stray note, exact same window).
-func TestReadFileToolValidRangeUnchangedByRecovery(t *testing.T) {
-	root := t.TempDir()
-	writeTestFile(t, filepath.Join(root, "notes.txt"), "alpha\nbeta\ngamma\ndelta\nepsilon")
-
-	result := NewReadFileTool(root).Run(context.Background(), map[string]any{
-		"path":       "notes.txt",
-		"start_line": 2,
-		"end_line":   4,
-	})
-	if result.Status != StatusOK {
-		t.Fatalf("valid range failed: %s: %s", result.Status, result.Output)
-	}
-	// Byte-for-byte: header, blank separator, the exact selected lines, and no
-	// recovery note or trailing content. An altered header/separator or a stray
-	// out-of-range line would fail this where a substring check would not.
-	const want = "File: notes.txt (lines 2-4 of 5)\n\n2 | beta\n3 | gamma\n4 | delta"
-	if result.Output != want {
-		t.Fatalf("valid-range output changed by the recovery path:\n got: %q\nwant: %q", result.Output, want)
-	}
-}

internal/tools/read_file.go

@@ -106,18 +106,8 @@ func renderReadFileRange(absolutePath string, relativePath string, total int, st
 	if endLine == 0 || endLine > total {
 		endLine = total
 	}
-	// A backwards range (end_line < start_line) is a caller slip, not a fatal
-	// error. Recover the way an end_line past EOF is already recovered a few lines
-	// up (clamped down to the last line): clamp end_line UP to start_line and read
-	// just that one line. Erroring here instead cost the caller a whole retry for
-	// an off-by-arithmetic mistake, and it was inconsistent — start_line past EOF
-	// and end_line past EOF both recover gracefully; only this case hard-failed.
-	// The recovery is surfaced in the output (rangeNote) so it is never silent: the
-	// caller sees it read a different range than it asked for and why.
-	rangeNote := ""
 	if endLine < startLine {
-		rangeNote = fmt.Sprintf("(note: end_line %d was before start_line %d, so only line %d was read — pass end_line >= start_line to read a wider range)", endLine, startLine, startLine)
-		endLine = startLine
+		return errorResult("Error: Invalid arguments for read_file: end_line must be greater than or equal to start_line")
 	}
 
 	truncated := false
@@ -145,12 +135,7 @@ func renderReadFileRange(absolutePath string, relativePath string, total int, st
 		budgetedOutput = newHeadTailOutputBudgetBuilder(readOutputBudgetBytes, "use start_line/end_line or max_lines to continue with a smaller range")
 	}
 	budgetedOutput.WriteString(header)
-	budgetedOutput.WriteString("\n")
-	if rangeNote != "" {
-		budgetedOutput.WriteString(rangeNote)
-		budgetedOutput.WriteString("\n")
-	}
-	budgetedOutput.WriteString("\n")
+	budgetedOutput.WriteString("\n\n")
 	if err := appendReadFileRange(budgetedOutput, absolutePath, startLine, selectedLines, width); err != nil {
 		return errorResult("Error reading file " + relativePath + ": " + err.Error())
 	}

internal/tui/provider_wizard.go

@@ -1959,12 +1959,49 @@ func (wizard *providerWizardState) filteredModels() []providerWizardModel {
 	return models
 }
 
-func (model providerWizardModel) displayLabel() string {
-	description := strings.TrimSpace(model.Description)
-	if description != "" && !providerWizardGenericModelDescription(description) {
-		return description
+// A model Description is only a good row label when it reads like a display
+// NAME — "Grok 4.3" for x-ai/grok-4.3 — which is what the field is for, and why
+// the row prefers it over an ugly raw ID.
+//
+// Providers do not all honour that. Aggregators commonly return a prose blurb
+// instead ("Fast DeepSeek model for efficient chat, coding help, and agent
+// loops"), which fails as a label twice over: it overflows the row, and because
+// such blurbs are written per model FAMILY rather than per model, several
+// DIFFERENT models collapse to byte-identical rows. A picker then offers two
+// visually identical entries with the distinguishing ID visible only in the
+// detail line of whichever one is highlighted.
+//
+// providerWizardGenericModelDescription cannot catch these: it rejects
+// descriptions that are vague ("live model", "catalog default"), whereas these
+// are specific — just shared and sentence-shaped. So the test is shape, not
+// wording: a name is short and few-worded; anything longer is prose, and the ID
+// (unique by construction) makes the better label.
+const (
+	providerWizardMaxModelNameChars = 28
+	providerWizardMaxModelNameWords = 4
+)
+
+func providerWizardDescriptionIsDisplayName(description string) bool {
+	trimmed := strings.TrimSpace(description)
+	if trimmed == "" || providerWizardGenericModelDescription(trimmed) {
+		return false
 	}
-	return model.ID
+	if len(trimmed) > providerWizardMaxModelNameChars {
+		return false
+	}
+	return len(strings.Fields(trimmed)) <= providerWizardMaxModelNameWords
+}
+
+func (model providerWizardModel) displayLabel() string {
+	if providerWizardDescriptionIsDisplayName(model.Description) {
+		return strings.TrimSpace(model.Description)
+	}
+	if id := strings.TrimSpace(model.ID); id != "" {
+		return id
+	}
+	// ID-less sentinel rows built in currentModel ("model name required",
+	// "no matching models") would otherwise render blank.
+	return strings.TrimSpace(model.Description)
 }
 
 func (model providerWizardModel) secondaryText() string {

internal/tui/provider_wizard_test.go

@@ -1787,3 +1787,37 @@ func providerWizardIDs(descriptors []providercatalog.Descriptor) []string {
 	}
 	return ids
 }
+
+// A provider that returns prose blurbs instead of display names must not
+// collapse distinct models into identical rows. Reproduces the reported picker
+// where two "Open-weight GPT model..." and two "Kimi multimodal agent model..."
+// rows were indistinguishable, with the ID visible only for the highlighted one.
+func TestProviderWizardModelRowsStayDistinctWithProseDescriptions(t *testing.T) {
+	wizard := &providerWizardState{
+		step:        providerWizardStepModel,
+		modelSource: "models.dev",
+		models: []providerWizardModel{
+			{ID: "gpt-oss-120b", Description: "Open-weight GPT model for self-hosted reasoning and instruction-following workloads"},
+			{ID: "gpt-oss-20b", Description: "Open-weight GPT model for self-hosted reasoning and instruction-following workloads"},
+			{ID: "kimi-k2-thinking", Description: "Kimi multimodal agent model for visual understanding, coding, and planning"},
+			{ID: "kimi-k2-instruct", Description: "Kimi multimodal agent model for visual understanding, coding, and planning"},
+			{ID: "x-ai/grok-4.3", Description: "Grok 4.3"},
+		},
+	}
+	view := plainRender(t, strings.Join(wizard.renderModelStep(96), "\n"))
+
+	// every prose-described model is identified by its unique ID
+	for _, id := range []string{"gpt-oss-120b", "gpt-oss-20b", "kimi-k2-thinking", "kimi-k2-instruct"} {
+		if !strings.Contains(view, id) {
+			t.Errorf("model %q is not identifiable in the list:\n%s", id, view)
+		}
+	}
+	// a genuine display name is still preferred over the raw id
+	if !strings.Contains(view, "Grok 4.3") {
+		t.Errorf("friendly display name was lost:\n%s", view)
+	}
+	// the prose blurb must not be a row label
+	if strings.Contains(view, "❯ Open-weight GPT model") {
+		t.Errorf("prose blurb still used as a row label:\n%s", view)
+	}
+}

internal/tui/sidebar.go

@@ -94,12 +94,26 @@ func (m model) sidebarAvailable() bool {
 	if widthTier(m.width) < tierMedium {
 		return false
 	}
-	// Full-screen overlays (setup, wizards, pickers, the empty-state suggestion
-	// list) take over the chat column and render at full width; suppress the
-	// second column while any is active so their geometry and mouse hit-testing
-	// stay full-width as before.
+	// Full-screen overlays (setup, wizards, pickers) take over the chat column and
+	// render at full width; suppress the second column while any is active so
+	// their geometry and mouse hit-testing stay full-width as before.
+	//
+	// The `/` command palette is deliberately NOT in this list. It is not a
+	// full-screen overlay: suggestionOverlay draws it via centerRenderedBlock at
+	// minInt(width, suggestionPaletteMaxWidth) — a centred box capped at 76 cells
+	// — floating over the chat column rather than replacing it. Suppressing the
+	// sidebar for it collapsed the whole layout on every keystroke of `/`: the
+	// plan panel dropped out of the sidebar and re-rendered inline at the bottom
+	// and the transcript re-wrapped to full width, which is at its most jarring
+	// mid-run with a live plan on screen. Since the sidebar already requires the
+	// medium tier (>= 80 cells) the palette is always strictly narrower than the
+	// chat column here, so the two never contend for the same cells.
+	//
+	// Mouse hit-testing is unaffected: sidebarLineAtMouse carries its own
+	// suggestionsActive() guard, so clicks still go to the palette and not to the
+	// sidebar rows underneath it.
 	if m.setup.visible || m.helpOverlay || m.leaderHelpOverlay || m.providerWizard != nil || m.mcpAddWizard != nil ||
-		m.mcpManager != nil || m.picker != nil || m.suggestionsActive() {
+		m.mcpManager != nil || m.picker != nil {
 		return false
 	}
 	// Home/welcome screen: stay single-column until there's real conversation, so

internal/tui/sidebar_test.go

@@ -631,3 +631,58 @@ func TestTwoColumnTranscriptViewWidth(t *testing.T) {
 func stripSidebar(lines []string) string {
 	return ansiPattern.ReplaceAllString(strings.Join(lines, "\n"), "")
 }
+
+// The `/` command palette must NOT collapse the sidebar. It is a centred box
+// capped at suggestionPaletteMaxWidth floating over the chat column, not a
+// full-screen overlay — suppressing the second column for it dropped the plan
+// out of the sidebar and re-rendered it inline at the bottom on every `/`,
+// which is at its most disruptive mid-run with a live plan on screen. The
+// genuinely full-width overlays must still suppress it.
+func TestSidebarSurvivesCommandPalette(t *testing.T) {
+	base := func() model {
+		m := runningPlanModel(t, 3)
+		m.altScreen = true
+		m.height = 40
+		m.headerPrinted = true
+		m.transcript = append(m.transcript, transcriptRow{kind: rowToolCall, tool: "read_file", detail: "main.go"})
+		return m
+	}
+
+	m := base()
+	if !m.sidebarActive() {
+		t.Fatal("precondition: sidebar should be active for a wide alt-screen model with a plan")
+	}
+
+	// `/` palette open: sidebar stays, so the plan keeps its home and the layout
+	// does not reflow.
+	m.suggestions = []commandSuggestion{{Name: "/model", Desc: "Pick a model."}, {Name: "/plan", Desc: "Show planning mode status."}}
+	if !m.suggestionsActive() {
+		t.Fatal("precondition: suggestions should be active")
+	}
+	if !m.sidebarActive() {
+		t.Error("command palette must not collapse the sidebar")
+	}
+	if got := m.renderPinnedPlanPanel(m.chatColumnWidth(), 10); got != "" {
+		t.Errorf("plan must stay in the sidebar, not fall back to the pinned panel:\n%s", got)
+	}
+	// The palette never contends for the sidebar's cells: the two-column path
+	// renders it at width = chatColumnWidth, so it is centred inside the chat
+	// column and cannot overlap the sidebar.
+	chatW := m.chatColumnWidth()
+	for _, line := range strings.Split(plainRender(t, m.suggestionOverlay(chatW)), "\n") {
+		if w := lipgloss.Width(line); w > chatW {
+			t.Errorf("palette line is %d wide, wider than the chat column %d — it would overlap the sidebar", w, chatW)
+		}
+	}
+	// Clicks still belong to the palette, not the sidebar rows beneath it.
+	if _, ok := m.sidebarLineAtMouse(tea.MouseClickMsg{Button: tea.MouseLeft}); ok {
+		t.Error("sidebar must not take mouse hits while the palette is open")
+	}
+
+	// A genuinely full-width overlay still suppresses the sidebar.
+	full := base()
+	full.picker = &commandPicker{}
+	if full.sidebarActive() {
+		t.Error("a full-screen picker must still collapse the sidebar")
+	}
+}