fix(whatsapp): resolve LID aliases on modern platforms/ session layout

[fesalfayed]

What does this PR do?

expand_whatsapp_aliases in gateway/whatsapp_identity.py reads the bridge's lid-mapping-*.json files to collapse a WhatsApp LID to its phone alias, but it hardcodes the session directory:

session_dir = get_hermes_home() / "whatsapp" / "session"

The WhatsApp adapter writes those files — and points the bridge at them via --session — through the consolidated-layout helper instead:

get_hermes_dir("platforms/whatsapp/session", "whatsapp/session")

get_hermes_dir(new, old) returns the legacy path only when it already exists on disk, otherwise the new platforms/... path. So on any install without a legacy whatsapp/session directory the bridge writes mappings to platforms/whatsapp/session while the resolver looks in whatsapp/session — empty/nonexistent. The resolver finds no mappings, returns the bare LID, the allowlist check misses, and the inbound message is silently dropped. The module docstring's "single source of truth … so the two paths can never drift apart" is contradicted by this line.

This routes the resolver through the same get_hermes_dir(...) call the adapter uses, so the read and write paths stay in lockstep on both the modern and legacy layouts and can't drift again.

Same root-cause-not-symptom approach as #35859 (merged): one minimal in-style change at the divergence point, no new bookkeeping, plus a regression test that fails on the old path and passes on the fixed one.

Related Issue

Fixes #36664

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Changes Made

• gateway/whatsapp_identity.py — expand_whatsapp_aliases: resolve session_dir via get_hermes_dir("platforms/whatsapp/session", "whatsapp/session") (the adapter's helper) instead of the hardcoded get_hermes_home() / "whatsapp" / "session".
• tests/gateway/test_whatsapp_identity.py — resolution test on both the modern platforms/whatsapp/session and legacy whatsapp/session layouts.

How to Test

pytest tests/gateway/test_whatsapp_identity.py -q

The modern-layout test fails on main (expand_whatsapp_aliases("<lid>@lid") returns {"<lid>"} only) and passes with this change (returns {"<lid>", "<phone>"}). Broader suite green:

pytest tests/gateway/test_whatsapp_identity.py tests/gateway/test_session.py \
  tests/gateway/test_unauthorized_dm_behavior.py tests/gateway/test_pairing.py -q
# 149 passed

Checklist

Code

• My commit messages follow Conventional Commits
• My PR contains only changes related to this fix
• Tests pass
• I've added tests for my changes
• Tested on macOS 26.4, Python 3.11.15

Documentation & Housekeeping

• N/A — behavior fix, no config/doc/schema changes.

[fesalfayed]

Validation refresh and duplicate-context note:

• This PR keeps the resolver on the same get_hermes_dir("platforms/whatsapp/session", "whatsapp/session") path as the adapter.
• Dedicated regressions cover both modern consolidated layout and legacy layout.
• Local checks: ruff check . ✅, python scripts/check-windows-footguns.py --all ✅, python -m pytest tests/gateway/test_whatsapp_identity.py -q -o addopts='' → 2 passed, git diff --check ✅.

This is the same issue as #38712; happy for maintainers to take whichever branch they prefer, but this one includes both modern and legacy layout coverage.

[teknium1]

Merged via PR #54083 — your fix was cherry-picked onto current main with your authorship preserved in git log (commit 263ffec). As the issue author you submitted this first; thanks for the clean fix and tests. We added one extra E2E test covering the allowlist-authorization path on top.