feat(agent,agent-installer): add transactional policy store

[Benoît Cortier (CBenoit)]

Adds authenticated transactional package-policy management to Devolutions Agent, including deterministic validation, optimistic concurrency, atomic JSON persistence, secure path and ACL enforcement, and stable old-or-new runtime snapshots.

Adds structured tracing and Windows Event Log auditing, fail-closed watcher reconciliation, administrator and elevation enforcement for writes, and split unelevated/LocalSystem end-to-end coverage.

Stacked on #1937.
Final Gateway head: c1b72fe33b36dc1d80d79ee6d8d759d76ef9e275.
Shared contract: Devolutions/now-libraries#99 at ec592a91f95a66c8a79b7d612ed73d931ef74aeb.
Downstream integration: draft Devolutions/UniGetUI#5335 at 92e2d8c26ecefd0f9542909530aef228bcd1fa2f.
Validation: CI run 33254105745 passed all jobs.

[Benoît Cortier (CBenoit)]

Implementation notes:

• Replaces the watcher-owned policy mutation path with one serialized PolicyStore that publishes immutable Active/Missing/Invalid snapshots.
• Uses the exact ec592a91f95a66c8a79b7d612ed73d931ef74aeb now-libraries contract, keyed validation receipts, opaque disk-state tokens, and explicit Create/Update/Repair/ReplaceIdentity semantics.
• Restricts writable policy storage to securely resolved JSON paths with SYSTEM/Administrators-only protection, same-directory atomic publication, post-write verification, and synchronous post-publication reconciliation.
• Requires the existing caller-signature validation plus actual elevation and enabled Administrators membership for writes; the development signature bypass does not bypass authorization.
• Audits attempts and outcomes through structured tracing and the Agent Windows Event Log without policy content.
• Validation completed: diff check and rustfmt; 409 default and 413 dev-skip broker tests passed except the existing host-specific Winget AppExecAlias DACL baseline; sysevent-codes (1), sysevent-winevent (8), and win-api-wrappers (25) tests passed; workspace check and Clippy with warnings denied passed; Agent debug and release message-resource builds passed; unelevated Agent policy E2E passed. LocalSystem E2E is wired into Windows CI but could not run in this medium-integrity shell because PsExec could not install PSEXESVC.

Note

Human-tuned, LLM-assisted content.

[Benoît Cortier (CBenoit)]

CI repair update (be3a9edf):

• Resolves the verified policy parent through its held handle before comparing the leaf, so 8.3 parent aliases and case-only leaf differences are accepted without weakening location checks.
• Rejects policy files with multiple hard links using FILE_STANDARD_INFO.NumberOfLinks instead of relying on which link name GetFinalPathNameByHandleW reports.
• Runs the unelevated E2E suite through PsExec -l; the tester now fails immediately unless its token is both non-elevated and lacks enabled Administrators membership. LocalSystem remains a separate mode.
• Selects and validates one deterministic mc.exe result before exporting WindowsSdkVerBinPath.

Focused validation passed: 37 policy-store Windows tests, 3 token-wrapper tests, agent-policy-tester check, direct unelevated E2E with token assertion, rustfmt, diff check, and targeted Clippy with warnings denied. Workflow assertions for restricted launch and single message-compiler selection also passed; actionlint is not installed locally.

Note

Human-tuned, LLM-assisted content.

[Benoît Cortier (CBenoit)]

Follow-up CI repair (9c85810a): the restricted PsExec process could not create its transcript in the protected checkout. The wrapper now uses the user's low-integrity LocalLow\Temp directory for test artifacts and streams stdout/stderr back through the parent CI process, preserving the explicit non-elevated/non-admin token assertion and expected 403 behavior.

Local script parsing, workflow assertions, diff/rustfmt, agent-policy-tester check, and targeted Clippy passed.

Note

Human-tuned, LLM-assisted content.

[Benoît Cortier (CBenoit)]

Final CI status: run 33254105745 passed at c1b72fe33b36dc1d80d79ee6d8d759d76ef9e275, including the restricted unelevated and LocalSystem Agent policy E2E modes, Windows path/hardlink tests, and Agent release message-resource build. The worktree is clean and the pushed upstream SHA matches locally.

Note

Human-tuned, LLM-assisted content.