chore: cache prompt and refresh config for obot mcp

[cjellick]

This reworks the mcp-cli integration in nanobot. The big functional differences:

1. There is a single mcp-cli/config.json file for the agent stored at ROOT/.nanobot/mcp-cli/config.json
2. When a user starts a session, we get all their connected servers and append them to the system prompt. the intent here is to make it so that the agent knows right off the bat about the mcp servers the user has existing connections to. this is a point in time snapshot so that we dont keep changing the system prompt (thus ruining prompt caching).
3. Eliminates the mcp-cli skill and moves a shorter version to the system prompt. the goal here is to eliminate the getSkill tool call for something that we view as very fundamental to our agent. Because the version that is now in the system prompt is much shorter, we may need to add bits of the skill back in over time, but i'll let real world testing reveal that.

To accomplish the above, this integrates with a new tool on the obot-mcp server called obot_list_connected_mcp_servers, specifically for getting the users's connected MCP servers. That PR is here: obot-platform/obot-mcp-server#4

The logic caches the tools retrieved from obot_list_connected_mcp_servers for 15 minutes. Though the agent can force a refresh of the config through a dedicated new tool call for that.

Signed-off-by: Craig Jellick craig@obot.ai

[Copilot]

Pull request overview

This PR reworks Nanobot’s Obot MCP integration to keep the system prompt stable for caching while still exposing a snapshot of a user’s connected MCP servers, and adds a dedicated tool to refresh the local mcp-cli config on demand.

Changes:

• Introduces a new nanobot.obot-mcp-cli MCP server with a refreshMCPServerConfig tool and wires it into the system config hook.
• Fetches and caches a snapshot of connected MCP servers (15 min TTL) and appends a sanitized snapshot to the system prompt.
• Removes the mcp-cli skill file and updates tests/docs accordingly; adds bash env handling to set MCP_CONFIG_PATH automatically for mcp-cli invocations.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pkg/servers/system/skills_test.go	Updates skill expectations after removing the mcp-cli skill.
pkg/servers/system/skills/mcp-cli.md	Removes the mcp-cli skill content (now moved into system prompt docs).
pkg/servers/system/server.go	Routes bash env setup through new Obot MCP env helper.
pkg/servers/system/obot_mcp_bash_env.go	Adds logic to inject MCP_API_KEY and set MCP_CONFIG_PATH for mcp-cli commands.
pkg/servers/system/mcp_servers_test.go	Removes tests for dynamic MCP server management from system package.
pkg/servers/system/config_test.go	Updates expectations and validates presence of refresh tool based on env configuration.
pkg/servers/system/config.go	Delegates Obot MCP wiring to obotmcp.ConfigureIntegration and avoids nanobot.summary.
pkg/servers/system/bash_env_test.go	Adds tests for the new bash env behavior.
pkg/servers/obotmcp/server.go	Adds new MCP server exposing refreshMCPServerConfig.
pkg/servers/obotmcp/config.go	Implements prompt snapshot injection + tool/server wiring.
pkg/servers/obotmcp/fetch.go	Adds cached fetch of connected MCP servers via obot_list_connected_mcp_servers.
pkg/servers/obotmcp/mcpcli_config.go	Writes the generated mcp-cli config under .nanobot/mcp-cli/config.json.
pkg/servers/obotmcp/dynamic.go	Moves dynamic MCP server add/remove logic into obotmcp package.
pkg/servers/obotmcp/server_test.go	Adds tests for snapshot sanitization/caching and dynamic server behavior.
pkg/servers/obotmcp/mcpcli_config_test.go	Adds tests verifying config generation and refresh error behavior.
pkg/runtime/runtime.go	Registers the new nanobot.obot-mcp-cli server.
pkg/config/agents/nanobot.md	Adds shortened mcp-cli rules + refresh guidance to the agent prompt.

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[njhale]

The code looks good to me functionally

[njhale]

I'm curious as to whether most models will:
A) do this at most once
B) do this every time they attempt to call an MCP server with mcp-cli

[cjellick]

claude does it at most once. doesnt do it on follow up calls ... and this bit is carried forward from the skill. we actually had to add it after initial testing showed the llm would try to get it right by trial and error.

[njhale]

nit: t.Context()

[cjellick]

ack. FYI, just so I don't have to soend unnecessary cycles on this, I don't intend to address any nits.

[njhale]

nit: this and a bunch of other places can use block declarations

Suggested change

	const configuredMCPServersPromptSessionKey = "configuredMCPServersPrompt"
	const configuredMCPServersPromptFieldMaxRunes = 200
	const (
	configuredMCPServersPromptSessionKey = "configuredMCPServersPrompt"
	configuredMCPServersPromptFieldMaxRunes = 200
	)