Implement Stage A: rule engine, validation, audit, and safety gates

Completes 109 of 121 tasks. Every remaining task needs a tenant connection
(T055, T056, T101-T103) or an Azure Automation account (T115-T121).

  354 offline Pester tests      PASS
  Engine purity (Principle IV)  PASS
  Sanitization (SC-013)         PASS  (156 files)
  Graph module loaded in tests  none  (SC-008 holds)

What landed
  - Four-layer configuration validation with stable finding codes, covering
    every VR-002 and VR-003 condition, plus a 23-fixture invalid-config corpus
  - Run loop, audit records (NDJSON through a single sink), summaries,
    reconciliation, and exit codes 0-6
  - Persistence behind a single write-body builder whose result always has
    exactly one key
  - Invoke-PersonaEngine.ps1 and Edit-PersonaEngineConfig.ps1
  - Six docs, two pipelines, traceability matrix, V-5a and sanitization records

Three deviations from tasks.md, each recorded in its status block

  T033 is not in Resolve-UserPersona. evaluationErrorThreshold is run-level
  state and the rule engine is pure; a counter there would break Principle IV.
  It lives in New-PersonaRunCounter and is applied in the run loop.

  A new src/Engine/ layer holds Invoke-PersonaEngineRun. The entry script
  imports the manifest, which requires Microsoft.Graph.Authentication, so a
  loop living only inside it could not run on a machine without the Graph SDK
  and SC-004 could not be proven at all. The entry script is now a thin
  wrapper and what ships is what is tested.

  The invalid-config corpus is generated by a committed script, with the
  generated fixtures committed too, so a reviewer sees the fixture in the diff.

Defects found by running the code, not by reading it

  Group and role ID lists were double-wrapped: @(Get-PersonaGroupIdPage ...)
  around a comma-returned array collapsed every membership list into one
  bogus space-joined entry. That is a silent false non-match, exactly what
  FR-013 exists to prevent.

  A 403 whose status appears only in the exception message parsed as $null,
  which the retry policy treats as a transport error - five requests per
  account against a tenant already refusing. Status extraction now falls back
  to the message text, bounded to 400-599.

  The sanitization scan walked tracked files only, so it covered 34 of 156
  files and none of this phase's code. It now scans untracked non-ignored
  files too, and a negative control confirms it catches a planted leak.

  Test-Json reports one error per violating location, not first-failure-only
  as the V-5a draft claimed. Record and pin corrected.

Enforcement remains blocked on the V-4 security sign-off.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

specs/001-persona-engine/verification/sanitization.md

@@ -0,0 +1,76 @@
+# Sanitization scan result (SC-013)
+
+**Status**: PASS
+**Date**: 2026-08-20
+**Task**: T113
+**Scanner**: [tests/Test-Sanitization.ps1](../../../tests/Test-Sanitization.ps1)
+**Files scanned**: 156
+
+## What is scanned
+
+`git ls-files --cached --others --exclude-standard` — tracked files **and** untracked files that are
+not gitignored.
+
+The original scanner walked `git ls-files` alone, which covered only tracked files. That made the
+gate useless where it matters most: a leaked identifier in a file that has not been committed yet is
+precisely the one worth catching, and scanning only what is already in history means the scan passes
+right up until the commit that makes it too late. At the time this was found, the scan was covering
+34 of the repository's 156 files and none of the implementation written in this phase.
+
+`--exclude-standard` keeps gitignored build output and local scratch files out, so the scan covers
+exactly what a commit would add.
+
+## Patterns
+
+| Pattern | Exemptions |
+| --- | --- |
+| GUIDs | Placeholder-shaped GUIDs (`00000000-0000-0000-0000-0000000000a0`); the module manifest's own `GUID =` identity line |
+| Email addresses and UPNs | RFC 2606 / RFC 6761 reserved domains: `example.com/net/org`, `.invalid`, `.test`, `.localhost` |
+| `onmicrosoft.com` domains | none |
+| JWT and bearer-token shapes | none |
+| Assigned secret, password, or key literals | none |
+| PEM private key blocks | none |
+
+Two exemptions were added during this scan, both narrow and both for things that cannot be replaced
+with a placeholder:
+
+**Reserved domains.** `alex.employee@example.invalid` is guaranteed by RFC to be unresolvable.
+Rejecting reserved domains would push fixtures toward addresses that merely *look* fake, which is
+worse — the difference between "obviously synthetic" and "probably nobody's" is the entire reason the
+reserved list exists.
+
+**The module manifest GUID.** A PowerShell module manifest must carry a genuine unique GUID as its
+identity; it is what distinguishes this module from another of the same name. It identifies the
+module, not a tenant. The exemption is **line-level** (`^\s*GUID\s*=`), not file-level: exempting the
+whole manifest would let a real identifier land anywhere in it.
+
+## Verification of the scanner itself
+
+A negative control was run: a scratch file containing an email address on a real-world commercial
+domain and a randomly generated real-shaped GUID was added to the working tree **without** committing
+it. The scan failed with two findings and named both, by file and line. The file was then removed and
+the scan returned to PASS.
+
+The offending values are described here rather than quoted, because quoting them would make this
+record itself a finding — which the scan promptly demonstrated when an earlier draft did exactly
+that. That is the control working.
+
+Without a negative control, a scanner that had silently stopped matching would report the same green
+result as one that is working.
+
+## Result
+
+```
+Sanitization scan passed: no tenant data, credentials, or real identifiers found.
+```
+
+## Standing obligations
+
+This is a point-in-time result, not a property of the repository. The scan is **gate 1** of
+[pipelines/validate.yml](../../../pipelines/validate.yml) and runs before every other gate on every
+pull request — deliberately first, because a leaked identifier is a problem whether or not the code
+compiles, and every later gate prints file contents into build logs.
+
+Runtime audit records legitimately contain real UPNs and Object IDs, which are approved for logs. No
+such value may ever be committed. When attaching evidence to a verification record (V-1, V-2, V-3),
+redact identifiers to placeholders first.