refactor(diff): move rendering to output layer

[TFM-HITESH]

Summary

Move vaar diff text and JSON rendering into internal/output/diff and remove the obsolete internal/report compatibility facade.

Why

This completes the existing diff output migration described in Discussion #58 and keeps CLI orchestration separate from typed output rendering.

Closes #71.

Type

• Bug fix
• New rule
• Parser change/fix
• Reporter change/fix
• Documentation
• CI / Release
• Build
• Performance improvement/change
• Internal refactor
• Hotfix

Breaking change

• No
• Yes (describe required migration)

Changes

• Added typed text and JSON renderers under internal/output/diff.
• Updated the diff CLI to delegate rendering to the output layer.
• Removed diff formatting and JSON DTO ownership from internal/cli.
• Deleted the obsolete internal/report compatibility facade.
• Added exact-output, JSON, boundary, and secret-safety tests.

User-visible changes

None. Existing diff output, JSON schema, quiet mode, exit codes, and error behavior are unchanged.

Validation

Commands run:

• gofmt -w <touched Go files>
• make lint
• go test ./...
• go run ./cmd/vaar lint ...

Additional commands:

go test -trimpath ./...
go vet ./...
make build
go test ./internal/output/diff ./internal/cli ./internal/diff

Tests

• Added tests
• Updated existing tests
• No tests needed (explain)

Documentation

• Updated documentation
• Not applicable

Release notes

Moved diff text and JSON rendering into the layered output package and removed the obsolete report facade.

Reviewer notes

Please pay special attention to:

• Exact preservation of text and JSON output.
• Empty JSON arrays remaining arrays rather than null.
• Secret non-disclosure.
• Preservation of --quiet, exit codes, and operational errors.
• Complete removal of internal/report.
• CLI dependency direction toward internal/output/diff.

Checklist

• PR title follows Conventional Commits
• Code is formatted
• Tests pass
• Documentation is updated (if needed)
• Release note added (if needed)
• No real secrets, credentials or sensitive data is included

Summary by CodeRabbit

• New Features

  • Improved diff output for human-readable and JSON formats.
  • JSON results now consistently represent missing keys with empty arrays when applicable.
  • Diff output preserves difference direction and avoids exposing dotenv values.

• Bug Fixes

  • Improved messaging for clean results and singular or plural missing keys.

• Tests

  • Added comprehensive coverage for text and JSON diff rendering, formatting, ordering, and sensitive-value protection.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 480d79cc-045f-4299-89d2-5d26cd859739

📥 Commits

Reviewing files that changed from the base of the PR and between 5db9ddc and 6312393.

📒 Files selected for processing (8)

• internal/cli/diff.go
• internal/cli/diff_test.go
• internal/output/diff/diff.go
• internal/output/diff/diff_test.go
• internal/output/doc.go
• internal/report/json.go
• internal/report/report_test.go
• internal/report/text.go

💤 Files with no reviewable changes (3)

• internal/report/text.go
• internal/report/report_test.go
• internal/report/json.go

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📝 Walkthrough

Walkthrough

The diff CLI now delegates text and JSON rendering to internal/output/diff. The new package preserves output structure, ordering, empty arrays, and value non-disclosure. The obsolete internal/report compatibility package was removed.

Changes

Diff output migration

Layer / File(s)	Summary
Diff renderer implementation internal/output/diff/...	Adds typed text and JSON renderers with exact formatting, stable missing-key ordering, empty-array normalization, and dotenv value non-disclosure tests.
CLI integration and validation internal/cli/diff.go, internal/cli/diff_test.go	The CLI delegates rendering to internal/output/diff. Tests verify the import boundary and update the JSON payload helper name.
Output package scope internal/output/doc.go	Documents the scope of command-specific output subpackages and excludes compatibility facades. The obsolete internal/report package and tests are removed.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related issues

• Issue 71: Directly tracks moving diff rendering into internal/output/diff and removing internal/report.
• Issue 70: Covers the broader migration from internal/report to dedicated internal/output packages.

Possibly related PRs

• envaar/vaar#81: Applies an analogous CLI rendering migration for lint output.
• envaar/vaar#53: Introduces the internal/diff.Result data consumed by the new renderers.

Suggested reviewers: shreyagupta1202

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: moving diff rendering into the output layer.
Linked Issues check	✅ Passed	The changes satisfy issue #71 by moving diff rendering, preserving output behavior, deleting internal/report, and adding required tests.
Out of Scope Changes check	✅ Passed	The changes remain within issue #71, including the documented removal of the obsolete internal/report compatibility facade.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[chatgpt-codex-connector]

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[Copilot]

Pull request overview

Moves vaar diff rendering responsibilities into the output layer (internal/output/diff) and completes removal of the obsolete internal/report facade, keeping CLI orchestration focused on IO/flags/exit codes while typed renderers own formatting.

Changes:

• Added internal/output/diff text + JSON renderers for diff.Result (including empty-array normalization for JSON).
• Updated internal/cli/diff.go to delegate rendering to internal/output/diff.
• Removed the internal/report compatibility package and its tests; updated internal/output package documentation.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/report/text.go	Removed obsolete forwarding facade (lint text).
internal/report/json.go	Removed obsolete forwarding facade (lint JSON).
internal/report/report_test.go	Removed tests for the deleted internal/report facade.
internal/output/doc.go	Clarified output-layer scope (command-specific subpackages like lint/diff).
internal/output/diff/diff.go	New diff text/JSON renderers and JSON empty-array normalization.
internal/output/diff/diff_test.go	Added exact-output tests for diff text/JSON rendering behavior.
internal/cli/diff.go	CLI now delegates diff rendering to internal/output/diff.
internal/cli/diff_test.go	Added import-direction guard test and updated JSON payload type in tests.

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