fix(gateway): default /model to session scope on messaging platforms

[liuhao1024]

What does this PR do?

When users pick models via Telegram/Discord/Slack picker menus, the switch now defaults to session-scoped unless --global is explicitly provided. This prevents accidental global config changes from platform picker interactions, which cannot send --global/--session flags.

Previously, platform picker taps silently persisted to config.yaml because resolve_persist_behavior() fell back to model.persist_switch_by_default=True. This UX failure meant a user selecting a model from a Telegram menu unintentionally made a permanent global configuration change — the opposite of CLI users, who can explicitly opt into persistence with --global.

Related Issue

Fixes #61458

Type of Change

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

Changes Made

• gateway/slash_commands.py: Added context-aware default for messaging platforms. If source.platform != Platform.LOCAL and no explicit --global/--session flags are present, treat as if --session was passed (session-scoped by default).
• tests/gateway/test_model_picker_persist.py: Updated test_picker_tap_persists_by_default to test_picker_tap_is_session_scoped_by_default_on_messaging_platforms to reflect the new expected behavior — picker taps on messaging platforms now apply session overrides in-memory but do not persist to config.yaml.

How to Test

1. Start a Hermes gateway with Telegram adapter enabled.
2. In a Telegram DM, send /model to open the inline keyboard picker.
3. Select a model (e.g., "gpt-5.5") by tapping it.
4. Observe that:
   • The model switch works (confirmation message shows the new model).
   • The session override is applied in-memory (subsequent messages use the new model).
   • config.yaml is NOT modified (the default model remains unchanged).
5. Test with explicit flags:
   • /model gpt-5.5 --session → session-scoped (same as default on messaging platforms).
   • /model gpt-5.5 --global → persists to config.yaml (explicit opt-in).
6. Run the updated test: pytest tests/gateway/test_model_picker_persist.py -v — all three tests pass.

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/gateway/test_model_picker_persist.py -v and all tests pass
• I've added tests for my changes (updated existing test to reflect new behavior)
• I've tested on my platform: macOS (verified test suite passes)

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) — affects all messaging platforms equally (Telegram, Discord, Slack, etc.)
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

[tonydwb]

Code Review Summary

Verdict: LGTM

What the PR Does

Default /model picker usage on messaging platforms (Telegram, Discord, Slack, etc.) to session scope, preventing accidental global config changes when users pick models via platform menus.

Assessment

• Correctness: The heuristic correctly identifies messaging platforms by checking source.platform is not None and source.platform != Platform.LOCAL. The session-scoped override is applied in-memory while leaving config.yaml untouched.
• Testing: New test test_picker_tap_is_session_scoped_by_default_on_messaging_platforms verifies both that the session override IS set and that config.yaml remains unchanged.
• Security: No security concerns. This reduces accidental config changes — a safety improvement.

Note: PR was previously unreviewed.

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Reviewed by Hermes Agent

[tonydwb]

Code Review Summary

Verdict: Comment

Overview

• Defaults /model to session scope on messaging platforms
• Small fix (+41/-13)

Looks Good

• Clean, targeted fix
• No security concerns

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Reviewed by Hermes Agent

[teknium1]

Thanks for the focused gateway fix. Current main still resolves a no-flag /model command through resolve_persist_behavior(False, False) (gateway/slash_commands.py:1420-1430), whose default is persistence (hermes_cli/model_switch.py:416-443). That value controls both the picker config write (gateway/slash_commands.py:1647-1674) and typed-command config write (gateway/slash_commands.py:1893-1923).

The PR changes the common decision before those paths, preserves explicit --global, and adds regression assertions that the in-session override is set while config.yaml remains unchanged. The target region has not changed since the PR base (git log -L 1420,1432:gateway/slash_commands.py), so salvage should be mechanical.

Automated hermes-sweeper review.

[teknium1]

Merged via PR #67946 — your commit from #58371 was cherry-picked onto current main with your authorship preserved in git log (rebase merge). The session-only default you built for --provider switches is now the default for ALL /model switches on every surface, so this PR's gateway-specific half is covered by the same root fix. Thanks for the clean fix and the tests — they shipped with your name on them.