format/status: split FormatStatusSummary aggregation from rendering

[psaab]

Closes #4656.

What

Pure code-motion refactor of FormatStatusSummary
(pkg/dataplane/userspace/format/status.go), which was a ~600-line
god-function (lines 103-711) doing both the single accumulation pass over
the status snapshot and the per-section rendering inline
(codex-review-174 #13, cold-path class-A).

• Aggregation pass extracted into aggregateStatusSummary(status) statusSummaryAggregates
  (the struct holds every counter previously kept in ~90 locals plus the two
  derived residuals).
• Each cohesive rendering block moved into a dedicated writeXxxSection
  helper: overview, event stream, security counters, NAT, source-NAT pools,
  TX+CoS summary, three-color policers, TX-path counters, slow path, worker
  runtime. New helpers live in status_sections.go.
• FormatStatusSummary is now a 22-line orchestrator calling the helpers in
  the original top-to-bottom order.

Guardrails (from the issue) — all preserved

• ONE pass over bindings: aggregateStatusSummary is the only place that
  walks status.Bindings (and Queues, and CoSInterfaces); render helpers
  read the returned struct and never re-iterate. No extra status fetches.
• Deterministic order: same section sequence, same sorts on the source-NAT
  pool and three-color policer tables.
• Omit-zero: every conditional suppression (SYN-cookie, generated-reply
  drops/sent/budget/rate-limit, CoS block, optional slow-path lines,
  worker-runtime dead/idle rows) moved verbatim.

Byte-identity gate

New TestFormatStatusSummaryGolden compares the full rendered output against
testdata/status_summary.golden, generated from the pre-refactor code over a
fixture that exercises every conditional section (wall-clock-relative fields
left zero so the golden is stable). The golden passes byte-for-byte after the
split — proof the output text is unchanged. Existing substring assertions in
status_test.go also stay green.

Validation

• go build ./... clean
• go vet ./pkg/dataplane/userspace/format/ clean
• gofmt -w applied
• go test ./pkg/dataplane/userspace/... green (16 status-summary tests incl. the golden gate)

🤖 Generated with Claude Code

https://claude.ai/code/session_015oARShYtiJJ2H4UB4nXGqi

[Copilot]

Pull request overview

Refactors the userspace dataplane FormatStatusSummary formatter by separating the single-pass snapshot aggregation from the per-section rendering, while adding a golden-output test to ensure byte-for-byte output stability.

Changes:

• Extracted the counter accumulation work into aggregateStatusSummary(status) statusSummaryAggregates.
• Moved each formatting block into focused writeXxxSection helpers in a new status_sections.go.
• Added a golden test (TestFormatStatusSummaryGolden) and fixture output to gate output identity across refactors.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg/dataplane/userspace/format/status.go	Shrinks FormatStatusSummary into an orchestrator that aggregates once and delegates rendering to section helpers.
pkg/dataplane/userspace/format/status_sections.go	Introduces the aggregate struct + single-pass aggregator and the extracted writeXxxSection render helpers.
pkg/dataplane/userspace/format/status_golden_test.go	Adds a deterministic fixture + golden comparison (with -update support) to lock output bytes.
pkg/dataplane/userspace/format/testdata/status_summary.golden	Golden output for full rendered status summary.
_Log.md	Logs the refactor per repository logging rules.