type: user

role: user

content:
Combined spec + code-quality review of Task 9 (textual diff types + Textual()) in worktree `/Users/steve.briggs/projects/operations/.claude/worktrees/birdseye`. Do spec first, then quality.

Diff: `git diff b7ab5b6..16193cc -- apps/birdseye/`

## Spec — What Was Requested

Create:
- `apps/birdseye/internal/diff/types.go` with `FileStatus` enum (`StatusModified=0, StatusAdded, StatusRemoved`), `(s FileStatus) String() string`, `FileDiff{Path, Status, Unified, Adds, Dels}`, `SemanticChange{Kind, Name, Status, Detail}`, `Result{Files, Semantic}`.
- `apps/birdseye/internal/diff/textual.go` with `Textual(a, b archive.Module) []FileDiff`. Behavior:
  - Union of file keys, sorted lexicographically by path
  - Identical bodies skipped
  - Added/Removed/Modified each map to a different `FileDiff` produced by helper functions (`addedDiff`, `removedDiff`, `modifiedDiff`)
  - Modified uses `gotextdiff` myers ComputeEdits + ToUnified, then `.String()` (or equivalent stringification)
  - Adds/Dels populated by `countLines` for modifications and `countNonEmptyLines` for added/removed
- `textual_test.go` with 5 tests covering Added, Removed, Modified, Identical, Sorted

The implementer reports one deviation: `gotextdiff.Unified` implements `fmt.Formatter` not `fmt.Stringer`, so they used `fmt.Sprintf("%v", unified)` instead of `unified.String()`. **This is acceptable** — flag it but do not fail. (Actually verify by reading the actual `gotextdiff` package source if necessary.)

Commit message exact: `feat(birdseye): textual unified diff between extracted modules`.

## Quality Focus

- API correctness: does `fmt.Sprintf("%v", unified)` produce a sensible unified diff format? (Look at the test output via the file body or just rely on tests passing.)
- Style: helpers `addedDiff`/`removedDiff`/`modifiedDiff` cleanly factored?
- Allocation: `prefixLines` uses `strings.Builder` with `Grow`? `Textual` preallocates slices where size is known?
- Correctness: the `+++`/`---` prefix exclusion in `countLines` handles the file header lines properly (so they're not counted as add/del lines)?
- Test independence: helpers `mkArchive` and `findFile` are self-contained?

## Report Format

**Spec:** ✅ compliant OR ❌ issues with file:line
**Quality:**
- Strengths: 1-2 bullets
- Issues: Critical / Important / Minor
- Assessment: APPROVED | NEEDS_CHANGES

Be terse.

userType: external

entrypoint: cli

gitBranch: worktree-birdseye


content:
- migrate-flux-app: Use when migrating a Flux CD application from the infrastructure/kubernetes/application-deployments repo to the application-deployment repo. Covers copying app folders, updating kustomizations, committing, pushing, and creating merge requests.
- app-infra-generate: Generate an application-infrastructure Terraform module from a YAML spec produced by app-infra-spec. Reads pattern files and a versions manifest to produce main.tf, variables.tf, outputs.tf, overlay guidance, and a triage list.
- app-infra-spec: Structured questionnaire to gather requirements for an application-infrastructure Terraform module. Produces a YAML spec for the app-infra-generate skill.
- obsidian-load: Load context from Obsidian notes in the `Claude/` directory into the current conversation.
- obsidian-save: Save current conversation context to an Obsidian note under the `Claude/` directory.
- mind:search: Search memories for specific content or patterns
- mind:stats: Show memory statistics and storage information
- mind:recent: Show recent memories and activity timeline
- mind:ask: Ask questions about memories and get context-aware answers
- superpowers:using-git-worktrees: Use when starting feature work that needs isolation from current workspace or before executing implementation plans - ensures an isolated workspace exists via native tools or git worktree fallback
- superpowers:receiving-code-review: Use when receiving code review feedback, before implementing suggestions, especially if feedback seems unclear or technically questionable - requires technical rigor and verification, not performative agreement or blind implementation
- superpowers:finishing-a-development-branch: Use when implementation is complete, all tests pass, and you need to decide how to integrate the work - guides completion of development work by presenting structured options for merge, PR, or cleanup
- superpowers:dispatching-parallel-agents: Use when facing 2+ independent tasks that can be worked on without shared state or sequential dependencies
- superpowers:writing-plans: Use when you have a spec or requirements for a multi-step task, before touching code
- superpowers:using-superpowers: Use when starting any conversation - establishes how to find and use skills, requiring Skill tool invocation before ANY response including clarifying questions
- superpowers:writing-skills: Use when creating new skills, editing existing skills, or verifying skills work before deployment
- superpowers:requesting-code-review: Use when completing tasks, implementing major features, or before merging to verify work meets requirements
- superpowers:executing-plans: Use when you have a written implementation plan to execute in a separate session with review checkpoints
- superpowers:verification-before-completion: Use when about to claim work is complete, fixed, or passing, before committing or creating PRs - requires running verification commands and confirming output before making any success claims; evidence before assertions always
- superpowers:brainstorming: You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
- superpowers:systematic-debugging: Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes
- superpowers:test-driven-development: Use when implementing any feature or bugfix, before writing implementation code
- superpowers:subagent-driven-development: Use when executing implementation plans with independent tasks in the current session
- mind:memory: Claude Mind - Search and manage Claude's persistent memory stored in a single portable .mv2 file
- mind:mind: Claude Mind - Search and manage Claude's persistent memory stored in a single portable .mv2 file
- update-config: Use this skill to configure the Claude Code harness via settings.json. Automated behaviors ("from now on when X", "each time X", "whenever X", "before/after X") require hooks configured in settings.json - the harness executes these, not Claude, so memory/preferences cannot fulfill them. Also use for: permissions ("allow X", "add permission", "move permission to"), env vars ("set X=Y"), hook troubleshooting, or any changes to settings.json/settings.local.json files. Examples: "allow npm commands", "add bq permission to global settings", "move permission to user settings", "set DEBUG=true", "when claude stops show X". For simple settings like theme/model, suggest the /config command.
- keybindings-help: Use when the user wants to customize keyboard shortcuts, rebind keys, add chord bindings, or modify ~/.claude/keybindings.json. Examples: "rebind ctrl+s", "add a chord shortcut", "change the submit key", "customize keybindings".
- simplify: Review changed code for reuse, quality, and efficiency, then fix any issues found.
- fewer-permission-prompts: Scan your transcripts for common read-only Bash and MCP tool calls, then add a prioritized allowlist to project .claude/settings.json to reduce permission prompts.
- loop: Run a prompt or slash command on a recurring interval (e.g. /loop 5m /foo). Omit the interval to let the model self-pace. - When the user wants to set up a recurring task, poll for status, or run something repeatedly on an interval (e.g. "check the deploy every 5 minutes", "keep running /babysit-prs"). Do NOT invoke for one-off tasks.
- schedule: Create, update, list, or run scheduled remote agents (routines) that execute on a cron schedule. - When the user wants to schedule a recurring remote agent, set up automated tasks, create a cron job for Claude Code, or manage their scheduled agents/routines. Also use when the user wants a one-time scheduled run ("run this once at 3pm", "remind me to check X tomorrow").
- claude-api: Build, debug, and optimize Claude API / Anthropic SDK apps. Apps built with this skill should include prompt caching. Also handles migrating existing Claude API code between Claude model versions (4.5 → 4.6, 4.6 → 4.7, retired-model replacements).
TRIGGER when: code imports `anthropic`/`@anthropic-ai/sdk`; user asks for the Claude API, Anthropic SDK, or Managed Agents; user adds/modifies/tunes a Claude feature (caching, thinking, compaction, tool use, batch, files, citations, memory) or model (Opus/Sonnet/Haiku) in a file; questions about prompt caching / cache hit rate in an Anthropic SDK project.
SKIP: file imports `openai`/other-provider SDK, filename like `*-openai.py`/`*-generic.py`, provider-neutral code, general programming/ML.
- init: Initialize a new CLAUDE.md file with codebase documentation
- review: Review a pull request
- security-review: Complete a security review of the pending changes on the current branch

type: attachment


type: message

role: assistant

type: text

text: I'll review the implementation by reading the relevant files.

service_tier: standard

attributionAgent: general-purpose

attributionPlugin: superpowers

type: assistant


Bash

command: cd /Users/steve.briggs/projects/operations && git diff b7ab5b6..16193cc -- apps/birdseye/ --name-only

description: List files changed in the diff

type: direct

speed: standard


content:
diff --git a/apps/birdseye/go.mod b/apps/birdseye/go.mod
index fdd5177..93c54a8 100644
--- a/apps/birdseye/go.mod
+++ b/apps/birdseye/go.mod
@@ -3,6 +3,7 @@ module github.com/immuta/operations/apps/birdseye
 go 1.25.5

 require (
+	github.com/hexops/gotextdiff v1.0.3
 	github.com/immuta/operations/services/crow v0.0.0-20260512210412-d8eb33139c1a
 	github.com/spf13/cobra v1.9.1
 	golang.org/x/sync v0.20.0
diff --git a/apps/birdseye/go.sum b/apps/birdseye/go.sum
index 7f4069b..f201662 100644
--- a/apps/birdseye/go.sum
+++ b/apps/birdseye/go.sum
@@ -1,4 +1,6 @@
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
+github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
diff --git a/apps/birdseye/internal/diff/textual.go b/apps/birdseye/internal/diff/textual.go
new file mode 100644
index 0000000..1edba21
--- /dev/null
+++ b/apps/birdseye/internal/diff/textual.go
@@ -0,0 +1,119 @@
+package diff
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/hexops/gotextdiff"
+	"github.com/hexops/gotextdiff/myers"
+	"github.com/hexops/gotextdiff/span"
+
+	"github.com/immuta/operations/apps/birdseye/internal/archive"
+)
+
+// Textual returns a FileDiff per file that differs between a and b,
+// sorted by path. Files identical in both archives are not included.
+func Textual(a, b archive.Module) []FileDiff {
+	all := make(map[string]struct{})
+	for k := range a.Files {
+		all[k] = struct{}{}
+	}
+	for k := range b.Files {
+		all[k] = struct{}{}
+	}
+	paths := make([]string, 0, len(all))
+	for k := range all {
+		paths = append(paths, k)
+	}
+	sort.Strings(paths)
+
+	out := make([]FileDiff, 0, len(paths))
+	for _, p := range paths {
+		ab, aok := a.Files[p]
+		bb, bok := b.Files[p]
+		switch {
+		case aok && bok:
+			if string(ab) == string(bb) {
+				continue
+			}
+			out = append(out, modifiedDiff(p, string(ab), string(bb)))
+		case !aok && bok:
+			out = append(out, addedDiff(p, string(bb)))
+		case aok && !bok:
+			out = append(out, removedDiff(p, string(ab)))
+		}
+	}
+	return out
+}
+
+func modifiedDiff(path, oldText, newText string) FileDiff {
+	edits := myers.ComputeEdits(span.URIFromPath(path), oldText, newText)
+	unified := gotextdiff.ToUnified(path, path, oldText, edits)
+	u := fmt.Sprintf("%v", unified)
+	adds, dels := countLines(u)
+	return FileDiff{Path: path, Status: StatusModified, Unified: u, Adds: adds, Dels: dels}
+}
+
+func addedDiff(path, newText string) FileDiff {
+	return FileDiff{
+		Path:    path,
+		Status:  StatusAdded,
+		Unified: "+++ " + path + "\n" + prefixLines(newText, "+"),
+		Adds:    countNonEmptyLines(newText),
+	}
+}
+
+func removedDiff(path, oldText string) FileDiff {
+	return FileDiff{
+		Path:    path,
+		Status:  StatusRemoved,
+		Unified: "--- " + path + "\n" + prefixLines(oldText, "-"),
+		Dels:    countNonEmptyLines(oldText),
+	}
+}
+
+func prefixLines(s, prefix string) string {
+	if s == "" {
+		return ""
+	}
+	lines := strings.Split(strings.TrimRight(s, "\n"), "\n")
+	var sb strings.Builder
+	sb.Grow(len(s) + len(lines)*len(prefix))
+	for _, l := range lines {
+		sb.WriteString(prefix)
+		sb.WriteString(l)
+		sb.WriteByte('\n')
+	}
+	return sb.String()
+}
+
+func countNonEmptyLines(s string) int {
+	if s == "" {
+		return 0
+	}
+	n := strings.Count(s, "\n")
+	if !strings.HasSuffix(s, "\n") {
+		n++
+	}
+	return n
+}
+
+func countLines(unified string) (adds, dels int) {
+	for _, line := range strings.Split(unified, "\n") {
+		if len(line) == 0 {
+			continue
+		}
+		switch line[0] {
+		case '+':
+			if !strings.HasPrefix(line, "+++") {
+				adds++
+			}
+		case '-':
+			if !strings.HasPrefix(line, "---") {
+				dels++
+			}
+		}
+	}
+	return adds, dels
+}
diff --git a/apps/birdseye/internal/diff/textual_test.go b/apps/birdseye/internal/diff/textual_test.go
new file mode 100644
index 0000000..812bf49
--- /dev/null
+++ b/apps/birdseye/internal/diff/textual_test.go
@@ -0,0 +1,86 @@
+package diff
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/immuta/operations/apps/birdseye/internal/archive"
+)
+
+func mkArchive(files map[string]string) archive.Module {
+	out := archive.Module{Files: make(map[string][]byte, len(files))}
+	for k, v := range files {
+		out.Files[k] = []byte(v)
+	}
+	return out
+}
+
+func findFile(t *testing.T, ds []FileDiff, path string) FileDiff {
+	t.Helper()
+	for _, d := range ds {
+		if d.Path == path {
+			return d
+		}
+	}
+	t.Fatalf("no FileDiff for %s; got %d entries", path, len(ds))
+	return FileDiff{}
+}
+
+func TestTextualAdded(t *testing.T) {
+	a := mkArchive(nil)
+	b := mkArchive(map[string]string{"new.tf": "x\n"})
+	ds := Textual(a, b)
+	d := findFile(t, ds, "new.tf")
+	if d.Status != StatusAdded {
+		t.Errorf("status = %v, want Added", d.Status)
+	}
+	if d.Adds != 1 || d.Dels != 0 {
+		t.Errorf("adds/dels = %d/%d", d.Adds, d.Dels)
+	}
+}
+
+func TestTextualRemoved(t *testing.T) {
+	a := mkArchive(map[string]string{"old.tf": "x\n"})
+	b := mkArchive(nil)
+	ds := Textual(a, b)
+	d := findFile(t, ds, "old.tf")
+	if d.Status != StatusRemoved {
+		t.Errorf("status = %v, want Removed", d.Status)
+	}
+	if d.Adds != 0 || d.Dels != 1 {
+		t.Errorf("adds/dels = %d/%d", d.Adds, d.Dels)
+	}
+}
+
+func TestTextualModified(t *testing.T) {
+	a := mkArchive(map[string]string{"m.tf": "alpha\nbeta\n"})
+	b := mkArchive(map[string]string{"m.tf": "alpha\nGAMMA\n"})
+	ds := Textual(a, b)
+	d := findFile(t, ds, "m.tf")
+	if d.Status != StatusModified {
+		t.Errorf("status = %v, want Modified", d.Status)
+	}
+	if !strings.Contains(d.Unified, "-beta") || !strings.Contains(d.Unified, "+GAMMA") {
+		t.Errorf("unified missing expected lines:\n%s", d.Unified)
+	}
+}
+
+func TestTextualIdenticalReturnsEmpty(t *testing.T) {
+	a := mkArchive(map[string]string{"m.tf": "x\n"})
+	b := mkArchive(map[string]string{"m.tf": "x\n"})
+	if got := Textual(a, b); len(got) != 0 {
+		t.Errorf("expected 0 diffs, got %d", len(got))
+	}
+}
+
+func TestTextualSortedByPath(t *testing.T) {
+	a := mkArchive(map[string]string{"z.tf": "a\n", "a.tf": "a\n"})
+	b := mkArchive(map[string]string{"z.tf": "b\n", "a.tf": "b\n"})
+	ds := Textual(a, b)
+	if len(ds) != 2 {
+		t.Fatalf("got %d diffs, want 2", len(ds))
+	}
+	if ds[0].Path != "a.tf" || ds[1].Path != "z.tf" {
+		t.Errorf("expected sorted by path; got %s, %s", ds[0].Path, ds[1].Path)
+	}
+}
diff --git a/apps/birdseye/internal/diff/types.go b/apps/birdseye/internal/diff/types.go
new file mode 100644
index 0000000..f30a14d
--- /dev/null
+++ b/apps/birdseye/internal/diff/types.go
@@ -0,0 +1,51 @@
+// Package diff produces FileDiff entries and optional SemanticChange
+// entries from a pair of extracted Modules. All functions are pure: no
+// I/O, no globals.
+package diff
+
+// FileStatus describes what happened to a file between the two versions.
+type FileStatus int
+
+const (
+	StatusModified FileStatus = iota
+	StatusAdded
+	StatusRemoved
+)
+
+func (s FileStatus) String() string {
+	switch s {
+	case StatusAdded:
+		return "added"
+	case StatusRemoved:
+		return "removed"
+	default:
+		return "modified"
+	}
+}
+
+// FileDiff is a per-file diff result. Unified holds the rendered diff
+// hunks; Adds/Dels are the count of added/removed lines for summary
+// rendering.
+type FileDiff struct {
+	Path    string
+	Status  FileStatus
+	Unified string
+	Adds    int
+	Dels    int
+}
+
+// SemanticChange is a single HCL-aware change. Kind is one of "resource",
+// "variable", "output", "provider", "locals", "data", or "module".
+type SemanticChange struct {
+	Kind   string
+	Name   string
+	Status FileStatus
+	Detail string
+}
+
+// Result is what cmd/diff renders. Semantic is nil unless --semantic was
+// requested.
+type Result struct {
+	Files    []FileDiff
+	Semantic []SemanticChange
+}


text: Now let me verify the `gotextdiff` package to confirm the `fmt.Formatter` vs `fmt.Stringer` question.


command: find /Users/steve.briggs/projects/operations/apps/birdseye -path "*/hexops/gotextdiff" -type d 2>/dev/null | head -5

description: Find gotextdiff package in vendor or module cache


command: find ~/go/pkg/mod/github.com/hexops -name "*.go" 2>/dev/null | head -20

description: Find gotextdiff in Go module cache


content: (Bash completed with no output)


content:
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/unified.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/diff_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/diff.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/myers/diff_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/myers/diff.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/difftest/difftest.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/difftest/difftest_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/testenv/testenv.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/testenv/testenv_112.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/token111.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/uri_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/token.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/uri_windows_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/utf16_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/token_test.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/uri.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/utf16.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/span.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/token112.go
/Users/steve.briggs/go/pkg/mod/github.com/hexops/gotextdiff@v1.0.3/span/parse.go


content:
1	// Copyright 2019 The Go Authors. All rights reserved.
2	// Use of this source code is governed by a BSD-style
3	// license that can be found in the LICENSE file.
4
5	package gotextdiff
6
7	import (
8		"fmt"
9		"strings"
10	)
11
12	// Unified represents a set of edits as a unified diff.
13	type Unified struct {
14		// From is the name of the original file.
15		From string
16		// To is the name of the modified file.
17		To string
18		// Hunks is the set of edit hunks needed to transform the file content.
19		Hunks []*Hunk
20	}
21
22	// Hunk represents a contiguous set of line edits to apply.
23	type Hunk struct {
24		// The line in the original source where the hunk starts.
25		FromLine int
26		// The line in the original source where the hunk finishes.
27		ToLine int
28		// The set of line based edits to apply.
29		Lines []Line
30	}
31
32	// Line represents a single line operation to apply as part of a Hunk.
33	type Line struct {
34		// Kind is the type of line this represents, deletion, insertion or copy.
35		Kind OpKind
36		// Content is the content of this line.
37		// For deletion it is the line being removed, for all others it is the line
38		// to put in the output.
39		Content string
40	}
41
42	// OpKind is used to denote the type of operation a line represents.
43	type OpKind int
44
45	const (
46		// Delete is the operation kind for a line that is present in the input
47		// but not in the output.
48		Delete OpKind = iota
49		// Insert is the operation kind for a line that is new in the output.
50		Insert
51		// Equal is the operation kind for a line that is the same in the input and
52		// output, often used to provide context around edited lines.
53		Equal
54	)
55
56	// String returns a human readable representation of an OpKind. It is not
57	// intended for machine processing.
58	func (k OpKind) String() string {
59		switch k {
60		case Delete:
61			return "delete"
62		case Insert:
63			return "insert"
64		case Equal:
65			return "equal"
66		default:
67			panic("unknown operation kind")
68		}
69	}
70
71	const (
72		edge = 3
73		gap  = edge * 2
74	)
75
76	// ToUnified takes a file contents and a sequence of edits, and calculates
77	// a unified diff that represents those edits.
78	func ToUnified(from, to string, content string, edits []TextEdit) Unified {
79		u := Unified{
80			From: from,
81			To:   to,
82		}
83		if len(edits) == 0 {
84			return u
85		}
86		c, edits, partial := prepareEdits(content, edits)
87		if partial {
88			edits = lineEdits(content, c, edits)
89		}
90		lines := splitLines(content)
91		var h *Hunk
92		last := 0
93		toLine := 0
94		for _, edit := range edits {
95			start := edit.Span.Start().Line() - 1
96			end := edit.Span.End().Line() - 1
97			switch {
98			case h != nil && start == last:
99				//direct extension
100			case h != nil && start <= last+gap:
101				//within range of previous lines, add the joiners
102				addEqualLines(h, lines, last, start)
103			default:
104				//need to start a new hunk
105				if h != nil {
106					// add the edge to the previous hunk
107					addEqualLines(h, lines, last, last+edge)
108					u.Hunks = append(u.Hunks, h)
109				}
110				toLine += start - last
111				h = &Hunk{
112					FromLine: start + 1,
113					ToLine:   toLine + 1,
114				}
115				// add the edge to the new hunk
116				delta := addEqualLines(h, lines, start-edge, start)
117				h.FromLine -= delta
118				h.ToLine -= delta
119			}
120			last = start
121			for i := start; i < end; i++ {
122				h.Lines = append(h.Lines, Line{Kind: Delete, Content: lines[i]})
123				last++
124			}
125			if edit.NewText != "" {
126				for _, line := range splitLines(edit.NewText) {
127					h.Lines = append(h.Lines, Line{Kind: Insert, Content: line})
128					toLine++
129				}
130			}
131		}
132		if h != nil {
133			// add the edge to the final hunk
134			addEqualLines(h, lines, last, last+edge)
135			u.Hunks = append(u.Hunks, h)
136		}
137		return u
138	}
139
140	func splitLines(text string) []string {
141		lines := strings.SplitAfter(text, "\n")
142		if lines[len(lines)-1] == "" {
143			lines = lines[:len(lines)-1]
144		}
145		return lines
146	}
147
148	func addEqualLines(h *Hunk, lines []string, start, end int) int {
149		delta := 0
150		for i := start; i < end; i++ {
151			if i < 0 {
152				continue
153			}
154			if i >= len(lines) {
155				return delta
156			}
157			h.Lines = append(h.Lines, Line{Kind: Equal, Content: lines[i]})
158			delta++
159		}
160		return delta
161	}
162
163	// Format converts a unified diff to the standard textual form for that diff.
164	// The output of this function can be passed to tools like patch.
165	func (u Unified) Format(f fmt.State, r rune) {
166		if len(u.Hunks) == 0 {
167			return
168		}
169		fmt.Fprintf(f, "--- %s\n", u.From)
170		fmt.Fprintf(f, "+++ %s\n", u.To)
171		for _, hunk := range u.Hunks {
172			fromCount, toCount := 0, 0
173			for _, l := range hunk.Lines {
174				switch l.Kind {
175				case Delete:
176					fromCount++
177				case Insert:
178					toCount++
179				default:
180					fromCount++
181					toCount++
182				}
183			}
184			fmt.Fprint(f, "@@")
185			if fromCount > 1 {
186				fmt.Fprintf(f, " -%d,%d", hunk.FromLine, fromCount)
187			} else {
188				fmt.Fprintf(f, " -%d", hunk.FromLine)
189			}
190			if toCount > 1 {
191				fmt.Fprintf(f, " +%d,%d", hunk.ToLine, toCount)
192			} else {
193				fmt.Fprintf(f, " +%d", hunk.ToLine)
194			}
195			fmt.Fprint(f, " @@\n")
196			for _, l := range hunk.Lines {
197				switch l.Kind {
198				case Delete:
199					fmt.Fprintf(f, "-%s", l.Content)
200				case Insert:
201					fmt.Fprintf(f, "+%s", l.Content)
202				default:
203					fmt.Fprintf(f, " %s", l.Content)
204				}
205				if !strings.HasSuffix(l.Content, "\n") {
206					fmt.Fprintf(f, "\n\\ No newline at end of file\n")
207				}
208			}
209		}
210	}
211


text: Good. Now I have everything I need. Let me also verify the worktree files directly exist as expected.


description: List diff package files in worktree


description: Check recent commits in worktree


content:
drwxr-xr-x steve.briggs staff 160 B  Tue May 12 23:39:15 2026 ..
.rw-r--r-- steve.briggs staff 2.2 KB Tue May 12 23:39:29 2026 textual_test.go
.rw-r--r-- steve.briggs staff 1.1 KB Tue May 12 23:39:42 2026 types.go
.rw-r--r-- steve.briggs staff 2.6 KB Tue May 12 23:44:54 2026 textual.go
drwxr-xr-x steve.briggs staff 160 B  Tue May 12 23:44:54 2026 .


content:
16193cc feat(birdseye): textual unified diff between extracted modules
b7ab5b6 chore(birdseye): promote x/sync to direct dep and clean swallowed-error comment
743c194 feat(birdseye): registry with cache-first Fetch and concurrent FetchPair
a278a7a feat(birdseye): on-disk module tarball cache with atomic writes
51ae45c feat(birdseye): registry cache interface and in-memory impl


text:
Good. Commit message matches exactly. Now I have all the information needed for the full review.

---

**Spec:** COMPLIANT

All required files are present with correct structure. Every spec item is satisfied:

- `types.go`: `FileStatus` enum with correct iota ordering (`StatusModified=0, StatusAdded, StatusRemoved`), `String()`, `FileDiff`, `SemanticChange`, `Result` — all present and correct.
- `textual.go`: `Textual()` unions file keys, sorts lexicographically, skips identical bodies, routes to `addedDiff`/`removedDiff`/`modifiedDiff` as specified. `modifiedDiff` uses `myers.ComputeEdits` + `gotextdiff.ToUnified`. `Adds`/`Dels` populated via `countLines` for modified and `countNonEmptyLines` for added/removed.
- `textual_test.go`: 5 tests covering Added, Removed, Modified, Identical, Sorted — all present.
- Commit message matches exactly: `feat(birdseye): textual unified diff between extracted modules`.

**Deviation confirmed acceptable:** `gotextdiff.Unified` implements `fmt.Formatter` (via `Format(f fmt.State, r rune)`) and does NOT implement `fmt.Stringer`. `fmt.Sprintf("%v", unified)` correctly invokes `Format`, producing proper unified diff output. The deviation report is accurate.

---

**Quality:**

Strengths:
- `prefixLines` uses `strings.Builder` with `Grow(len(s) + len(lines)*len(prefix))` — correct preallocation accounting for both original content and prefix overhead.
- `Textual` preallocates both `paths` (`make([]string, 0, len(all))`) and `out` (`make([]FileDiff, 0, len(paths))`), holding to the spec and project style guide.

Issues:

**Minor — `countNonEmptyLines` name vs behavior mismatch (`textual.go:94-100`):** The function counts all lines with content, but it actually counts non-empty lines by excluding the trailing newline via `HasSuffix` logic. However it does NOT skip blank lines in the middle of a file (e.g., `"a\n\nb\n"` → 3, not 2). The name implies empty lines are excluded but only the trailing newline is handled. This is unlikely to matter for Terraform files but the name is misleading. `countLines` (without "NonEmpty") would be more accurate.

**Minor — `addedDiff`/`removedDiff` use different header format from `modifiedDiff` (`textual.go:56-70`):** Modified files get `--- path` / `+++ path` from `gotextdiff.Format`. Added files get only `+++ path`, removed only `--- path`. This is reasonable and intentional, but there's no hunk header (`@@ ... @@`) for added/removed diffs — they're synthetic, not real unified diff format. This is a conscious simplification but worth noting if downstream consumers parse the `Unified` field as standard diff.

**Minor — `countLines` `@@` hunk header lines are not filtered (`textual.go:103-116`):** Lines starting with `@@` are context lines in unified diff; they begin with `@` not `+`/`-`, so they are correctly unaffected. However `\ No newline at end of file` lines (starting with `\`) are also silently ignored — correct by accident since `\` is not `+` or `-`. No bug, but fragile if the format ever changes.

**Assessment: APPROVED**

The implementation is clean, allocation-conscious, and fully spec-compliant. The minor naming imprecision in `countNonEmptyLines` is the only substantive note; it does not affect correctness for the expected input domain.