Fix file-level annotation input overflow and Enter-to-edit (#27)

* add plan: fix-file-annotation-bugs

* feat: fix file-level annotation input width overflow

Add prefixWidth parameter to newAnnotationInput so file-level annotations
use the correct width subtraction (12) matching the wider "💬 file: " prefix,
instead of the line-level value (6) which caused terminal overflow.

Related to #26

* feat: fix Enter key to edit existing file-level annotations

In handleEnterKey, check cursorOnFileAnnotationLine() before falling
through to startAnnotation(). When on a file annotation line
(diffCursor == -1), dispatch to startFileAnnotation() instead.

Related to #26

* fix: deduplicate handleEnterKey annotation branches

Author: umputun

docs/plans/completed/20260405-fix-file-annotation-bugs.md

@@ -0,0 +1,81 @@
+# Fix File-Level Annotation Bugs
+
+## Overview
+Fix two bugs where file-level annotations (`A` key) behave differently from line-level annotations (`a` key).
+Related to #26.
+
+**Bug 1**: file-level annotation input overflows terminal width because `newAnnotationInput`
+subtracts 6 chars (for `"💬 "` prefix) but `renderFileAnnotationHeader` renders the wider
+`"💬 file: "` prefix (6 extra visible chars).
+
+**Bug 2**: pressing Enter on a file annotation line does nothing. `handleEnterKey` always
+calls `startAnnotation()` which returns nil when `diffCursor == -1`. It never dispatches
+to `startFileAnnotation()`.
+
+## Context (from discovery)
+- `ui/annotate.go:15-22`: `newAnnotationInput` — width calc subtracts 6 for prefix
+- `ui/annotate.go:57-62`: `startFileAnnotation` — calls `newAnnotationInput` with same width
+- `ui/diffview.go:55-70`: `renderFileAnnotationHeader` — renders `"💬 file: "` (wider prefix)
+- `ui/model.go:1138-1162`: `handleEnterKey` — always calls `startAnnotation()` in diff pane
+- `ui/annotate.go:212-213`: `cursorOnFileAnnotationLine()` — already exists, checks `diffCursor == -1`
+
+## Development Approach
+- **Testing approach**: regular (code first, then tests)
+- Both fixes are small and isolated
+- **CRITICAL: every task MUST include new/updated tests**
+- **CRITICAL: all tests must pass before starting next task**
+
+## Solution Overview
+- **Bug 1**: pass a width offset parameter to `newAnnotationInput` so file annotations use a larger
+  subtraction. The file prefix `"💬 file: "` is ~12 visible chars vs line prefix `"💬 "` ~6 chars.
+- **Bug 2**: in `handleEnterKey`, check `cursorOnFileAnnotationLine()` before falling through
+  to `startAnnotation()`. If true, call `startFileAnnotation()` instead.
+
+## Implementation Steps
+
+### Task 1: Fix file-level annotation input width overflow
+
+**Files:**
+- Modify: `ui/annotate.go`
+- Modify: `ui/diffview.go`
+- Modify: `ui/model_test.go`
+
+- [x] change `newAnnotationInput` to accept a `prefixWidth int` parameter instead of hardcoded 6
+- [x] update `startAnnotation` call to pass 6 (line-level prefix width)
+- [x] update `startFileAnnotation` call to pass 12 (file-level prefix width: cursor col + `"💬 file: "` + margin)
+- [x] verify the rendered prefix in `renderFileAnnotationHeader` (`"💬 file: "`) matches the offset
+- [x] write test: file-level annotation input width is narrower than line-level to account for wider prefix
+- [x] run tests — must pass before task 2
+
+### Task 2: Fix Enter key to edit existing file annotation
+
+**Files:**
+- Modify: `ui/model.go`
+- Modify: `ui/model_test.go`
+
+- [x] in `handleEnterKey`, add branch before `startAnnotation()`: when `m.cursorOnFileAnnotationLine()`, call `startFileAnnotation()` instead
+- [x] write test: Enter on file annotation line (diffCursor == -1) triggers file annotation edit
+- [x] write test: Enter on file annotation line pre-fills existing annotation text
+- [x] write test: Enter on regular diff line still triggers line annotation (regression check)
+- [x] run tests — must pass before task 3
+
+### Task 3: Verify acceptance criteria
+
+- [x] verify: file-level annotation input stays within terminal width
+- [x] verify: Enter on existing file annotation opens edit with pre-filled text
+- [x] verify: line-level annotations still work identically
+- [x] run full test suite: `make test`
+- [x] run linter: `make lint`
+- [x] run formatters: `make fmt`
+
+### Task 4: [Final] Update documentation
+
+- [x] update CLAUDE.md if new patterns discovered
+- [x] move this plan to `docs/plans/completed/`
+
+## Post-Completion
+
+**Manual verification:**
+- create a file-level annotation with a long text, verify it doesn't overflow
+- navigate to file annotation line, press Enter, verify edit mode opens with pre-filled text
+- verify line-level annotations still work as before

ui/annotate.go

@@ -12,12 +12,13 @@ import (
 )
 
 // newAnnotationInput creates and focuses a text input for annotation editing.
-func (m *Model) newAnnotationInput(placeholder string) (textinput.Model, tea.Cmd) {
+// prefixWidth accounts for the visible prefix characters (cursor col + emoji + label + margin).
+func (m *Model) newAnnotationInput(placeholder string, prefixWidth int) (textinput.Model, tea.Cmd) {
 	ti := textinput.New()
 	ti.Placeholder = placeholder
 	cmd := ti.Focus()
 	ti.CharLimit = 500
-	ti.Width = max(10, m.diffContentWidth()-6) // cursor col + emoji prefix "💬 " + border margin
+	ti.Width = max(10, m.diffContentWidth()-prefixWidth)
 	return ti, cmd
 }
 
@@ -36,7 +37,7 @@ func (m *Model) startAnnotation() tea.Cmd {
 		return nil
 	}
 
-	ti, cmd := m.newAnnotationInput("annotation...")
+	ti, cmd := m.newAnnotationInput("annotation...", 6) // cursor col + emoji prefix "💬 " + border margin
 
 	// pre-fill with existing annotation if one exists
 	lineNum := m.diffLineNum(dl)
@@ -59,7 +60,7 @@ func (m *Model) startFileAnnotation() tea.Cmd {
 		return nil
 	}
 
-	ti, cmd := m.newAnnotationInput("file-level annotation...")
+	ti, cmd := m.newAnnotationInput("file-level annotation...", 12) // cursor col + "💬 file: " prefix + border margin
 
 	// pre-fill with existing file-level annotation if one exists
 	for _, a := range m.store.Get(m.currFile) {
@@ -74,7 +75,6 @@ func (m *Model) startFileAnnotation() tea.Cmd {
 	m.fileAnnotating = true
 	m.diffCursor = -1 // position cursor on the file annotation line
 	m.viewport.GotoTop()
-	m.viewport.SetContent(m.renderDiff())
 	return cmd
 }
 

ui/model.go

@@ -1154,7 +1154,12 @@ func (m Model) handleEnterKey() (tea.Model, tea.Cmd) {
 		}
 		return m, nil
 	case paneDiff:
-		cmd := m.startAnnotation()
+		var cmd tea.Cmd
+		if m.cursorOnFileAnnotationLine() {
+			cmd = m.startFileAnnotation()
+		} else {
+			cmd = m.startAnnotation()
+		}
 		m.viewport.SetContent(m.renderDiff())
 		return m, cmd
 	}

ui/model_test.go

@@ -2241,6 +2241,34 @@ func TestModel_AnnotationInputWidthNarrowTerminal(t *testing.T) {
 	assert.GreaterOrEqual(t, m.annotateInput.Width, 10, "file text input width should be at least 10")
 }
 
+func TestModel_FileAnnotationInputWidthNarrowerThanLineLevel(t *testing.T) {
+	// file-level annotation has wider prefix ("💬 file: " vs "💬 "), so input should be narrower
+	lines := []diff.DiffLine{
+		{NewNum: 1, Content: "line1", ChangeType: diff.ChangeAdd},
+	}
+	m := testModel([]string{"a.go"}, nil)
+	m.tree = newFileTree([]string{"a.go"})
+	m.currFile = "a.go"
+	m.diffLines = lines
+	m.diffCursor = 0
+	m.focus = paneDiff
+	m.width = 120
+	m.treeWidth = 30
+	m.treeHidden = false
+
+	// line-level annotation
+	m.startAnnotation()
+	lineWidth := m.annotateInput.Width
+
+	// file-level annotation
+	m.annotating = false
+	m.startFileAnnotation()
+	fileWidth := m.annotateInput.Width
+
+	assert.Greater(t, lineWidth, fileWidth, "file-level input should be narrower than line-level due to wider prefix")
+	assert.Equal(t, 6, lineWidth-fileWidth, "width difference should match prefix width difference (12-6=6)")
+}
+
 func TestModel_FileAnnotationSavesWithLineZero(t *testing.T) {
 	lines := []diff.DiffLine{
 		{NewNum: 1, Content: "line1", ChangeType: diff.ChangeContext},
@@ -2330,6 +2358,66 @@ func TestModel_FileAnnotationCursorHighlighted(t *testing.T) {
 	assert.Contains(t, rendered, "file: file note", "file annotation should be rendered")
 }
 
+func TestModel_EnterOnFileAnnotationLineTriggersFileAnnotation(t *testing.T) {
+	lines := []diff.DiffLine{
+		{NewNum: 1, Content: "line1", ChangeType: diff.ChangeContext},
+	}
+	m := testModel([]string{"a.go"}, nil)
+	m.tree = newFileTree([]string{"a.go"})
+	m.currFile = "a.go"
+	m.diffLines = lines
+	m.focus = paneDiff
+	m.diffCursor = -1 // on file annotation line
+	m.store.Add(annotation.Annotation{File: "a.go", Line: 0, Type: "", Comment: "existing note"})
+
+	// press enter on file annotation line - should start file annotation mode
+	result, cmd := m.Update(tea.KeyMsg{Type: tea.KeyEnter})
+	model := result.(Model)
+	assert.True(t, model.annotating, "enter on file annotation line should start annotation mode")
+	assert.True(t, model.fileAnnotating, "enter on file annotation line should set fileAnnotating")
+	assert.NotNil(t, cmd, "should return textinput blink command")
+}
+
+func TestModel_EnterOnFileAnnotationLinePreFillsText(t *testing.T) {
+	lines := []diff.DiffLine{
+		{NewNum: 1, Content: "line1", ChangeType: diff.ChangeContext},
+	}
+	m := testModel([]string{"a.go"}, nil)
+	m.tree = newFileTree([]string{"a.go"})
+	m.currFile = "a.go"
+	m.diffLines = lines
+	m.focus = paneDiff
+	m.diffCursor = -1 // on file annotation line
+	m.store.Add(annotation.Annotation{File: "a.go", Line: 0, Type: "", Comment: "pre-existing comment"})
+
+	// press enter - should pre-fill with existing annotation text
+	result, _ := m.Update(tea.KeyMsg{Type: tea.KeyEnter})
+	model := result.(Model)
+	assert.Equal(t, "pre-existing comment", model.annotateInput.Value(), "should pre-fill with existing file annotation")
+}
+
+func TestModel_EnterOnRegularDiffLineStillTriggersLineAnnotation(t *testing.T) {
+	lines := []diff.DiffLine{
+		{NewNum: 1, Content: "line1", ChangeType: diff.ChangeContext},
+		{NewNum: 2, Content: "added", ChangeType: diff.ChangeAdd},
+	}
+	m := testModel([]string{"a.go"}, nil)
+	m.tree = newFileTree([]string{"a.go"})
+	m.currFile = "a.go"
+	m.diffLines = lines
+	m.focus = paneDiff
+	m.diffCursor = 1 // on regular diff line, not file annotation
+	// add a file annotation to ensure it doesn't interfere
+	m.store.Add(annotation.Annotation{File: "a.go", Line: 0, Type: "", Comment: "file note"})
+
+	// press enter on regular line - should start line annotation, not file annotation
+	result, cmd := m.Update(tea.KeyMsg{Type: tea.KeyEnter})
+	model := result.(Model)
+	assert.True(t, model.annotating, "enter on regular line should start annotation mode")
+	assert.False(t, model.fileAnnotating, "enter on regular line should not set fileAnnotating")
+	assert.NotNil(t, cmd, "should return textinput blink command")
+}
+
 func TestModel_DeleteFileAnnotationViaD(t *testing.T) {
 	lines := []diff.DiffLine{
 		{NewNum: 1, Content: "line1", ChangeType: diff.ChangeContext},