What does this PR do?

resolve_session_name() in the Honcho client sanitizes gateway session keys and other identifiers but applies no length truncation. Gateway session keys like agent:main:telegram:group:-1001987654321:12345678:9876543210 with peer prefixes can produce sanitized strings exceeding 100 characters. Honcho's API enforces a 100-character limit on session IDs, causing API errors.

This PR caps the produced name to 100 characters at every return point.

Related Issue

Fixes #13868

Related: #13931

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• plugins/memory/honcho/client.py — added _MAX_SESSION_ID_LEN = 100 constant and applied [:_MAX_SESSION_ID_LEN] truncation at all return points in resolve_session_name() — session title, gateway session key, per-session ID, per-repo name, per-directory name, global fallback, and peer-prefixed variants.
• tests/honcho_plugin/test_session_name_length.py — 6 targeted tests

How to Test

1. pytest tests/honcho_plugin/test_session_name_length.py -v — 6 tests covering:
   • Source has truncation constant defined
   • Per-repo and per-directory strategies are truncated
   • Long gateway keys are truncated to <= 100 chars
   • Short keys are unchanged
2. Tested on macOS (Python 3.14)

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS (Python 3.14)

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Screenshots / Logs

N/A — see commit description and PR diff.