[8.19](backport #7794) refactor: clone ParsedPolicy in processPolicy to prevent shared-state races

[mergify]

Summary

• Adds ParsedPolicy.Clone() which returns a fully independent copy — every slice, map, and pointer field gets its own backing storage: SecretKeys and Policy.Namespaces via slices.Clone; Inputs, Roles (including RoleT.Raw bytes), and Outputs (including Output.Role pointers) deep-copied element by element; Agent and Fleet via maps.Clone; Policy.Data via model.ClonePolicyData.
• Also updates model.ClonePolicyData to clone its Agent and Fleet maps, OutputPermissions bytes, and OTel section maps via cloneOTelSection — necessary because prepareOTelExporters mutates per-component maps in-place; nil Inputs is preserved as nil.
• Moves the clone to the dispatch site in monitor.go: s.ch <- policy.pp.Clone() instead of &policy.pp. Each channel send now transfers an exclusively-owned *ParsedPolicy to its subscriber, so processPolicy receives a copy it already owns and can mutate freely — no implicit contract that callers must clone.
• processPolicy is unchanged in behaviour; the clone just moves upstream to the natural ownership-transfer boundary.
• Adds TestParsedPolicyCloneIsolation to verify that mutating each field of a clone does not affect the original.

References

Relates #7739

🤖 Generated with Claude Code

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This is an automatic backport of pull request #7794 done by Mergify.

[mergify]

Cherry-pick of c907276 has failed:

On branch mergify/bp/8.19/pr-7794
Your branch is up to date with 'origin/8.19'.

You are currently cherry-picking commit c907276.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   internal/pkg/policy/parsed_policy.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   internal/pkg/api/handleCheckin.go
	both modified:   internal/pkg/api/handleCheckin_test.go
	both modified:   internal/pkg/model/ext.go
	both modified:   internal/pkg/policy/monitor.go
	both modified:   internal/pkg/policy/parsed_policy_test.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[github-actions]

TL;DR

check-ci failed because the branch leaves internal/pkg/model/ext.go unformatted, so mage check:ci exits after detecting a required update. Run formatter/lint fixups and commit the resulting file change.

Remediation

• Regenerate formatting on the branch and commit the change in internal/pkg/model/ext.go (the log shows one extra blank line near deepCloneSliceAny/cloneMap, around ext.go line ~148).
• Re-run Buildkite (or locally run mage check:ci) to confirm the working tree stays clean.

Investigation details

Root Cause

This is a code-quality failure (formatting drift), not a runtime/test flake. The Run check-ci step invokes .buildkite/scripts/check_ci.sh → mage check:ci, and that check reports a diff in internal/pkg/model/ext.go then aborts because files would be modified.

Evidence

• Build: https://buildkite.com/elastic/fleet-server/builds/16772
• Job/step: Run check-ci (.buildkite/scripts/check_ci.sh)
• Key log excerpt:

  diff --git a/internal/pkg/model/ext.go b/internal/pkg/model/ext.go
  @@ -148,7 +148,6 @@ func deepCloneSliceAny(s []any) []any {
   	return r
   }
  -
   // cloneMap does a deep copy on a map of objects
  internal/pkg/model/ext.go: needs update
  Error: git update-index failure: running "git update-index --refresh" failed with exit code 1
  

Verification

Not run (detective workflow is read-only; analysis is based on the Buildkite artifact logs and PR metadata).

Follow-up

No matching open flaky-test issue applies here; this failure is deterministic formatting/check-ci drift.

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What is this? | From workflow: PR Buildkite Detective

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