[feature]: selective Kustomization reconcile in workload watch

[github-actions]

User Story

As a developer using ksail workload watch on a large Kubernetes repo,
I want the watch command to reconcile only the Kustomization subtree affected by my file changes,
So that reconcile latency is minimised and I get faster feedback without waiting for unrelated Kustomizations to re-run.

Context

The Weekly Roadmap — March 16, 2026 identifies selective Kustomization reconcile as the third highest unshipped "Now" priority:

In repos with 10+ Kustomizations, full-tree reconcile latency is the dominant UX pain point. Selective reconcile significantly reduces iteration latency and converts workload watch from a convenience into a genuinely fast inner-loop tool. No new dependencies required.

ksail workload watch currently triggers a full reconcile of k8s/ (or spec.workload.sourceDirectory) on any file change. In large repos with multiple Kustomization overlays (e.g., k8s/clusters/, k8s/apps/, k8s/infra/), this causes unnecessary reconcile cycles for all unrelated Kustomizations.

Approach

1. Map changed file → containing Kustomization — in the watch event handler, walk up the directory tree from the changed file path to find the nearest kustomization.yaml boundary.
2. Resolve the Flux Kustomization CR — identify which Flux Kustomization CR references the changed subtree by matching spec.path in the cluster's Kustomization objects.
3. Targeted reconcile — trigger flux reconcile kustomization (name) only for the affected Kustomization(s) via pkg/client/flux/ or pkg/client/reconciler/.
4. Full reconcile fallback — if the mapping is ambiguous, the changed file is at the root level, or the targeted CR cannot be determined, fall back to the existing full reconcile.
5. Preserve existing debounce/coalescing — maintain the existing debounce and event coalescing behaviour.

Key files:

• pkg/cli/cmd/workload/watch.go (or equivalent watch lifecycle path) — event handler to modify
• pkg/client/flux/ — Flux reconcile client
• pkg/client/reconciler/ — common reconciler base
• Watch infrastructure: wherever the file-change → reconcile trigger is wired

Acceptance Criteria

• Changing a file in a Kustomization subtree triggers reconcile of only that subtree's Kustomization CR
• Changing a top-level file (e.g., root kustomization.yaml) triggers full reconcile as before
• Ambiguous or unmappable changes fall back to full reconcile (no silent failures)
• Debounce and coalescing logic is preserved
• Unit tests cover the changed file → Kustomization mapping logic
• go build ./... and go test ./... pass
• No regressions in existing workload watch behaviour

Generated by Daily Plan · ◷

[github-actions]

🎯 Agentic Issue Triage

Summary: Backlog issue tracking selective Kustomization reconcile in workload watch — a Now priority item from the Weekly Roadmap — March 16, 2026. This is a valid, well-scoped performance improvement.

Analysis & Context

Roadmap priority: 🟢 Now — third highest unshipped priority. Reduces reconcile latency in multi-Kustomization repos, converting workload watch from a convenience into a genuinely fast inner-loop tool.

Technical approach:
The watch handler needs two new capabilities:

1. File → Kustomization mapping: Walk up the directory tree from the changed file path to find the nearest kustomization.yaml boundary, then match against Flux Kustomization CR spec.path fields
2. Targeted reconcile: Invoke flux reconcile kustomization (name) for only the affected CR(s), with full-reconcile fallback for ambiguous/root-level changes

Key files:

• pkg/cli/cmd/workload/ — watch command lifecycle (find the file-change → reconcile trigger)
• pkg/client/flux/ — Flux reconcile client
• pkg/client/reconciler/ — common reconciler base (shared between Flux and ArgoCD)

Edge cases to handle:

• Root-level kustomization.yaml changes → full reconcile
• Multiple Kustomizations affected by one change → reconcile each
• File outside any Kustomization boundary → full reconcile fallback
• Preserved debounce/coalescing behavior

Labels: Current labels (next, backlog, ai-generated) are appropriate. Note: this is a Now item in the roadmap.

Generated by Daily Plan · ◷