[jaredhicks]

Fixes #1101

Problem

A chart that renders annotations: or labels: with nothing under it leaves the map null.
On the strategic merge path, the three-way patch helm-diff computes then deletes the whole map, so --three-way-merge reports every annotation or label added outside the chart as removed.
helm upgrade keeps them, because it merges the release's ownership metadata into every object before it computes its own patch (setMetadataVisitor, pkg/action/validate.go), so the map it sends is never null.

Fix

Add the same ownership metadata to the new manifest before createPatch, so the patch matches the one the upgrade sends.
A new WithRelease(name, namespace) option to manifest.Generate carries the release identity; helm diff upgrade sets it.

The custom resource path is unaffected: cleanMetadataForPatch already removes these keys, and any map they leave empty, before comparing, so the added metadata does not count as a chart change.
The Helm keys are pruned from the output as before.

Tests

• TestCreatePatch_KeepsMetadataAddedOutsideTheChartUnderANullMap applies the patch as the API server does and checks that an annotation and a label added outside the chart survive. It fails without the fix.
• scripts/issues/1101.sh reproduces the issue on a cluster:
  • null annotations and null labels with metadata added outside the chart report no change (exit 2 before the fix);
  • the same with --three-way-merge-mode client;
  • an edit to an annotation the chart sets is still reported as drift;
  • helm upgrade keeps the metadata added outside the chart, which is the behavior the diff must agree with.
• make test and make lint pass; scripts/issues/run.sh passes on a fresh kind cluster for Bug: helm-diff shows - labels, if resource contains only app.kubernetes.io/managed-by label #1064, --three-way-merge reports removal of annotations/labels added outside the chart when the chart renders an empty map #1101, Diff is incorrect when values in values.yaml change and using local Chart #464, Diff failing when diffing helm hook jobs with --take-ownership flag #782 and helm diff --three-way-merge does not detect manual changes on Custom Resources (CRDs) #917.

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🟢 Approval recommended

No active review issues were identified in the changes aligning three-way patch generation with Helm ownership metadata.

No open issues 🎉

What changed in this PR

Addresses #1101 by aligning three-way patch generation with Helm’s ownership metadata handling, preventing false removal reports for externally added annotations and labels when a chart renders null metadata maps.

Changes:

• Passes the release name and namespace into manifest generation.
• Adds Helm ownership metadata to a copy of the target object before computing patches.
• Adds unit and cluster regression tests for metadata preservation and chart-owned annotation drift.

File	Description
scripts/​issues/​1101.sh	Exercises null-map preservation, client merge mode, drift detection, and Helm upgrade behavior.
manifest/​generate.go	Adds release options and injects ownership metadata before patch creation.
manifest/​generate_test.go	Verifies strategic patches preserve externally added annotations and labels.
cmd/​upgrade.go	Resolves the release namespace and passes release identity to manifest generation.

_{Review effort: Balanced}