feat(opencode-plugin): instruct model to create branch with conventional prefix

When no workflow is active, the plugin now instructs the model to first
create a branch with a meaningful name using conventional commit prefixes
(e.g., feat/add-new-feature, fix/bug-description) before calling
start_development. This ensures proper branch naming conventions are
followed from the start of each development session.

Author: mrsimpson

.vibe/development-plan-proud-garlics-sleep.md

@@ -0,0 +1,59 @@
+# Development Plan: repo (proud-garlics-sleep branch)
+
+*Generated on 2026-05-06 by Vibe Feature MCP*
+*Workflow: [minor](https://codemcp.github.io/workflows/workflows/minor)*
+
+## Goal
+Improve the opencode plugin by instructing the model in the first message of a session (when no workflow is active) to create a branch with a meaningful name using conventional-commit-prefix (e.g., `feat/add-new-provider`).
+
+## Key Decisions
+- **Where the first message instruction lives**: In `packages/opencode-plugin/src/plugin.ts`, the `chat.message` hook handles injecting instructions. When no workflow is active, it shows a generic "No Active Workflow Detected. You MUST initiate a new development workflow..." message.
+- **Current branch suggestion logic**: Located in `packages/mcp-server/src/tool-handlers/start-development.ts` (lines 113-133). When user is on main/master, it generates a branch name like `feature/development-YYYYMMDD`.
+- **Proposed change**: Modify the "no active workflow" instruction in the chat.message hook to also instruct the model to create a branch with a conventional-commit-prefix before calling start_development.
+- **Branch naming**: Use conventional commit prefixes like `feat/`, `fix/`, `refactor/`, `docs/`, etc., combined with a brief description of the task.
+
+## Notes
+- The "no active workflow" message is injected in two places in plugin.ts:
+  1. Lines 374-383: When handlerResult is not successful
+  2. Lines 392-402: When error includes 'CONVERSATION_NOT_FOUND'
+- Need to enhance both to include branch creation guidance with conventional commit prefix
+
+## Explore
+### Tasks
+- [x] Understand the plugin architecture and where instructions are injected
+- [x] Find the "no active workflow" message location
+- [x] Analyze existing branch suggestion logic in start-development handler
+- [x] Determine how to enhance the instruction message
+
+### Completed
+- Analyzed plugin.ts chat.message hook (lines 284-437) - this is where instructions are injected
+- Found "no active workflow" messages at lines 374-383 and 392-402 in plugin.ts
+- Reviewed start-development.ts generateBranchSuggestion() at lines 581-584
+- The current branch suggestion generates `feature/development-YYYYMMDD` which lacks conventional-commit-prefix
+
+## Implement
+### Tasks
+- [x] Modify "no active workflow" message in plugin.ts (lines 381 and 400) to include branch creation guidance with conventional commit prefix
+
+### Completed
+- Enhanced both "no active workflow" messages in plugin.ts to include guidance:
+  - "First, create a new branch with a meaningful name using a conventional commit prefix (e.g., `feat/add-new-feature`, `fix/bug-description`, `refactor/improve-logic`). Then call the `start_development` tool to begin."
+- This change ensures that when a user starts a new session without an active workflow, they'll be instructed to create a properly named branch before initiating a development workflow
+
+## Finalize
+### Tasks
+- [x] Code cleanup - verified no debug output, TODO/FIXME, or debugging code blocks exist
+- [x] Documentation review - no updates needed (change doesn't affect documented behavior)
+- [x] Final validation - changes verified via git diff, implementation is complete
+
+### Completed
+- Verified no debug output (console.log, debugger, etc.) in plugin source code
+- Verified no TODO/FIXME comments in modified files
+- Reviewed documentation (.vibe/docs/requirements.md, design.md, plugin README) - no updates needed
+- Change is a simple text modification to two string literals in plugin.ts
+- Implementation complete and ready for commit/PR
+
+
+
+---
+*This plan is maintained by the LLM. Tool responses provide guidance on which section to focus on and what tasks to work on.*

packages/opencode-plugin/src/plugin.ts

@@ -378,7 +378,7 @@ export const WorkflowsPlugin: Plugin = async (
               messageID: hookInput.messageID || output.message.id,
               type: 'text' as const,
               synthetic: true,
-              text: `No Active Workflow Detected. You MUST initiate a new development workflow before proceeding. Call the \`start_development\` tool to begin. Do NOT attempt any file edits or tool executions until a workflow is active.`,
+              text: `No Active Workflow Detected. You MUST initiate a new development workflow before proceeding. First, create a new branch with a meaningful name using a conventional commit prefix (e.g., \`feat/add-new-feature\`, \`fix/bug-description\`, \`refactor/improve-logic\`). Then call the \`start_development\` tool to begin. Do NOT attempt any file edits or tool executions until a workflow is active.`,
             } as (typeof output.parts)[0]);
             return;
           }
@@ -397,7 +397,7 @@ export const WorkflowsPlugin: Plugin = async (
               messageID: hookInput.messageID || output.message.id,
               type: 'text' as const,
               synthetic: true,
-              text: `No Active Workflow Detected. You MUST initiate a new development workflow before proceeding. Call the \`start_development\` tool to begin. Do NOT attempt any file edits or tool executions until a workflow is active.`,
+              text: `No Active Workflow Detected. You MUST initiate a new development workflow before proceeding. First, create a new branch with a meaningful name using a conventional commit prefix (e.g., \`feat/add-new-feature\`, \`fix/bug-description\`, \`refactor/improve-logic\`). Then call the \`start_development\` tool to begin. Do NOT attempt any file edits or tool executions until a workflow is active.`,
             } as (typeof output.parts)[0]);
             return;
           }