feat(openspec): add list command change proposal

openspec/changes/add-list-command/proposal.md

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+# Add List Command to OpenSpec CLI
+
+## Why
+
+Developers need visibility into available changes and their status to understand the project's evolution and pending work.
+
+## What Changes
+
+- Add `openspec list` command that displays all changes in the changes/ directory
+- Show each change name with task completion count (e.g., "add-auth: 3/5 tasks")
+- Display completion status indicator (✓ for fully complete, progress for partial)
+- Skip the archive/ subdirectory to focus on active changes
+- Simple table output for easy scanning
+
+## Impact
+
+- Affected specs: New capability `cli-list` will be added
+- Affected code:
+  - `src/cli/index.ts` - Add list command
+  - `src/core/list.ts` - New file with directory scanning and task parsing (~60 lines)

openspec/changes/add-list-command/specs/cli-list/spec.md

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+# List Command Specification
+
+## Purpose
+
+The `openspec list` command SHALL provide developers with a quick overview of all active changes in the project, showing their names and task completion status.
+
+## Behavior
+
+### Command Execution
+
+WHEN `openspec list` is executed
+THEN scan the `openspec/changes/` directory for change directories
+AND exclude the `archive/` subdirectory from results
+AND parse each change's `tasks.md` file to count task completion
+
+### Task Counting
+
+WHEN parsing a `tasks.md` file
+THEN count tasks matching these patterns:
+- Completed: Lines containing `- [x]`
+- Incomplete: Lines containing `- [ ]`
+AND calculate total tasks as the sum of completed and incomplete
+
+### Output Format
+
+WHEN displaying the list
+THEN show a table with columns:
+- Change name (directory name)
+- Task progress (e.g., "3/5 tasks" or "✓ Complete")
+- Status indicator:
+  - `✓` for fully completed changes (all tasks done)
+  - Progress fraction for partial completion
+
+Example output:
+```
+Changes:
+  add-auth-feature     3/5 tasks
+  update-api-docs      ✓ Complete
+  fix-validation       0/2 tasks
+  add-list-command     1/4 tasks
+```
+
+### Empty State
+
+WHEN no active changes exist (only archive/ or empty changes/)
+THEN display: "No active changes found."
+
+### Error Handling
+
+IF a change directory has no `tasks.md` file
+THEN display the change with "No tasks" status
+
+IF `openspec/changes/` directory doesn't exist
+THEN display error: "No OpenSpec changes directory found. Run 'openspec init' first."
+AND exit with code 1
+
+### Sorting
+
+Changes SHALL be displayed in alphabetical order by change name for consistency.
+
+## Why
+
+Developers need a quick way to:
+- See what changes are in progress
+- Identify which changes are ready to archive
+- Understand the overall project evolution status
+- Get a bird's-eye view without opening multiple files
+
+This command provides that visibility with minimal effort, following OpenSpec's philosophy of simplicity and clarity.

openspec/changes/add-list-command/tasks.md

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+# Implementation Tasks
+
+## 1. Core Implementation
+- [ ] 1.1 Create `src/core/list.ts` with list logic
+  - [ ] 1.1.1 Implement directory scanning (exclude archive/)
+  - [ ] 1.1.2 Implement task counting from tasks.md files
+  - [ ] 1.1.3 Format output as simple table
+- [ ] 1.2 Add list command to CLI in `src/cli/index.ts`
+  - [ ] 1.2.1 Register `openspec list` command
+  - [ ] 1.2.2 Connect to list.ts implementation
+
+## 2. Error Handling
+- [ ] 2.1 Handle missing openspec/changes/ directory
+- [ ] 2.2 Handle changes without tasks.md files
+- [ ] 2.3 Handle empty changes directory
+
+## 3. Testing
+- [ ] 3.1 Add tests for list functionality
+  - [ ] 3.1.1 Test with multiple changes
+  - [ ] 3.1.2 Test with completed changes
+  - [ ] 3.1.3 Test with no changes
+  - [ ] 3.1.4 Test error conditions
+
+## 4. Documentation
+- [ ] 4.1 Update CLI help text with list command
+- [ ] 4.2 Add list command to README if applicable