hermes - 💡(How to fix) Fix feat: batch profile model/provider reconfiguration + YAML-aware config set

Problem

hermes config set has two critical limitations:

1. No profile targeting — it only modifies the current active profile. There is no --profile flag to target a specific profile, making batch reconfiguration across multiple profiles impossible without manual scripting.

2. Destroys nested YAML — hermes config set model default-value flattens the entire model: block into a scalar, destroying nested keys like model.provider, model.base_url, model.api_mode, etc. This is actively dangerous and has broken production configs.

Example of the damage:

# Before
model:
  default: mimo-v2.5-free
  provider: opencode-zen
  base_url: https://opencode.ai/zen/v1
  api_mode: chat_completions

# After: hermes config set model test-value
model: test-value  # entire nested block destroyed

Users with multiple profiles (common for multi-agent setups with 10+ profiles) have no built-in way to batch-switch models/providers. The only option is custom scripts that directly patch YAML files.

Proposed Solution

Two features:

1. hermes config set --profile NAME KEY VALUE

Allow targeting a specific profile by name. Repeated --profile flags or --all for batch:

# Single profile
hermes config set --profile coder model.default claude-sonnet-4

# All profiles at once
hermes config set --all model.default claude-sonnet-4

# Multiple specific profiles
hermes config set --profile coder --profile dev-pm model.default claude-sonnet-4

2. YAML-aware nested key handling

hermes config set should properly handle nested keys using dot notation or YAML-aware merging:

# This should update model.default without destroying model.provider
hermes config set model.default claude-sonnet-4

# The setter should read the existing model block, update only the
# target key, and write it back preserving all other nested keys

Implementation should use a YAML library (ruamel.yaml or PyYAML) to load → modify → dump rather than regex or string replacement.

Current Workaround

Users rely on custom scripts like hermes-batch-model.sh that use Python regex to patch YAML files directly. This works but is fragile and requires maintaining external tooling for something the CLI should handle natively.

Impact

Multi-profile setups (kanban workers, role-based agents, dev/test splits) are a core Hermes feature. Batch model switching is a common workflow — switching to a new provider, testing a new model across all roles, rotating API keys. Without this, users with N profiles must either edit N config files manually or maintain custom scripts.

Suggested Labels

enhancement, cli