Adds a `modify` response type to pre_tool_call hooks so a hook can
transform tool arguments before the tool executes, instead of repairing
results afterwards via post_tool_call.
- hermes_cli/plugins.py: _dispatch_pre_tool_call_hooks() fires hooks once
and returns (block_message, modified_args); modify directives
shallow-merge into an accumulated dict built from the original args.
- agent/shell_hooks.py: _parse_response() accepts both the canonical
{"action": "modify", "args": {...}} and Claude Code-compatible
{"decision": "modify", "tool_input": {...}} wire formats.
- model_tools.py, agent/tool_executor.py, agent/agent_runtime_helpers.py:
dispatch sites migrated; modified args applied before execution.
- Docs + 10 new tests (merge semantics, precedence, block interplay).
Salvaged from PR #28953. Best fix for #18988.
Adds backend-neutral observer hooks for plugins: session, turn, API
request, tool, approval, and subagent lifecycle events with stable
correlation IDs (session_id, task_id, turn_id, api_request_id,
tool_call_id, parent/child subagent ids). Extends VALID_HOOKS with
api_request_error and subagent_start.
Hot path is zero-cost when no plugin subscribes: has_hook()/presence
checks gate all payload construction, request payloads are returned
by reference when no middleware rewrites, and the sanitized response
payload no longer embeds raw response objects.
Bundles the optional NeMo-Relay observability plugin
(plugins/observability/nemo_relay) as an in-repo consumer of the new
hooks, peer to the existing langfuse plugin. Fails open when the
optional nemo-relay package is not installed.
Authored-by: Bryan Bednarski <bbednarski@nvidia.com>
Salvaged from #29722 onto current main.
Bryan Bednarski