Remove diff command in favor of show command

README.md

@@ -118,9 +118,6 @@ AI: "Following the tasks in openspec/changes/add-user-profile-api/tasks.md:
 # View active changes (what's being worked on)
 openspec list
 
-# See the difference between proposed and current specs
-openspec diff add-2fa
-
 # Validate your changes are properly formatted
 openspec validate add-2fa --strict
 
@@ -137,7 +134,6 @@ openspec list              # See what changes you're working on
 openspec archive <change>  # Mark a change as complete after deployment
 
 # Also useful:
-openspec diff <change>     # See what specs will change
 openspec validate <change> # Check formatting before committing
 openspec show <change>     # View change details
 ```

openspec/README.md

@@ -55,7 +55,6 @@ After deployment, create separate PR to:
 openspec list                  # List active changes
 openspec list --specs          # List specifications
 openspec show [item]           # Display change or spec
-openspec diff [change]         # Show spec differences
 openspec validate [item]       # Validate changes or specs
 openspec archive [change]      # Archive after deployment
 
@@ -290,7 +289,6 @@ Only add complexity with:
 ```bash
 openspec list              # What's in progress?
 openspec show [item]       # View details
-openspec diff [change]     # What's changing?
 openspec validate --strict # Is it correct?
 openspec archive [change]  # Mark complete
 ```

openspec/changes/remove-diff-command/proposal.md

@@ -0,0 +1,81 @@
+# Remove Diff Command
+
+## Problem
+
+The `openspec diff` command adds unnecessary complexity to the OpenSpec CLI for several reasons:
+
+1. **Redundant functionality**: The `openspec show` command already provides comprehensive visualization of changes through structured JSON output and markdown rendering
+2. **Maintenance burden**: The diff command requires a separate dependency (jest-diff) and additional code complexity (~227 lines)
+3. **Limited value**: Developers can achieve better diff visualization using existing tools:
+   - Git diff for actual file changes
+   - The `show` command for structured change viewing
+   - Standard diff utilities for comparing spec files directly
+4. **Inconsistent with verb-noun pattern**: The command doesn't follow the preferred verb-first command structure that other commands are migrating to
+
+## Solution
+
+Remove the `openspec diff` command entirely and guide users to more appropriate alternatives:
+
+1. **For viewing change content**: Use `openspec show <change-name>` which provides:
+   - Structured JSON output with `--json` flag
+   - Markdown rendering for human-readable format
+   - Delta-only views with `--deltas-only` flag
+   - Full spec content visualization
+
+2. **For comparing files**: Use standard tools:
+   - `git diff` for version control comparisons
+   - System diff utilities for file-by-file comparisons
+   - IDE diff viewers for visual comparisons
+
+## Benefits
+
+- **Reduced complexity**: Removes ~227 lines of code and the jest-diff dependency
+- **Clearer user journey**: Directs users to the canonical `show` command for viewing changes
+- **Lower maintenance**: Fewer commands to maintain and test
+- **Better alignment**: Focuses on the core OpenSpec workflow without redundant features
+
+## Implementation
+
+### Files to Remove
+- `/src/core/diff.ts` - The entire diff command implementation
+- `/openspec/specs/cli-diff/spec.md` - The diff command specification
+
+### Files to Update
+- `/src/cli/index.ts` - Remove diff command registration (lines 8, 84-96)
+- `/package.json` - Remove jest-diff dependency
+- `/README.md` - Remove diff command documentation
+- `/openspec/README.md` - Remove diff command references
+- Various documentation files mentioning `openspec diff`
+
+### Migration Guide for Users
+
+Users currently using `openspec diff` should transition to:
+
+```bash
+# Before
+openspec diff add-feature
+
+# After - view the change proposal
+openspec show add-feature
+
+# After - view only the deltas
+openspec show add-feature --json --deltas-only
+
+# After - use git for file comparisons
+git diff openspec/specs openspec/changes/add-feature/specs
+```
+
+## Risks
+
+- **User disruption**: Existing users may have workflows depending on the diff command
+  - Mitigation: Provide clear migration guide and deprecation period
+
+- **Loss of visual diff**: The colored, unified diff format will no longer be available
+  - Mitigation: Users can use git diff or other tools for visual comparisons
+
+## Success Metrics
+
+- Successful removal with no broken dependencies
+- Documentation updated to reflect the change
+- Tests passing without the diff command
+- Reduced package size from removing jest-diff dependency

openspec/changes/remove-diff-command/tasks.md

@@ -0,0 +1,41 @@
+# Remove Diff Command - Tasks
+
+## 1. Remove Core Implementation
+- [x] Delete `/src/core/diff.ts`
+- [x] Remove DiffCommand import from `/src/cli/index.ts`
+- [x] Remove diff command registration from CLI
+
+## 2. Remove Specifications
+- [x] Delete `/openspec/specs/cli-diff/spec.md`
+- [x] Archive the spec for historical reference if needed
+
+## 3. Update Dependencies
+- [x] Remove jest-diff from package.json dependencies
+- [x] Run pnpm install to update lock file
+
+## 4. Update Documentation
+- [x] Update main README.md to remove diff command references
+- [x] Update openspec/README.md to remove diff command from command list
+- [x] Update CLAUDE.md template if it mentions diff command
+- [x] Update any example workflows that use diff command
+
+## 5. Update Related Files
+- [x] Search and update any remaining references to "openspec diff" in:
+  - Template files
+  - Test files (if any exist for diff command)
+  - Archive documentation
+  - Change proposals
+
+## 6. Add Deprecation Notice (Optional Phase)
+- [ ] Consider adding a deprecation warning before full removal
+- [ ] Provide helpful message directing users to `openspec show` command
+
+## 7. Testing
+- [x] Ensure all tests pass after removal
+- [x] Verify CLI help text no longer shows diff command
+- [x] Test that show command provides adequate replacement functionality
+
+## 8. Documentation of Alternative Workflows
+- [x] Document how to use `openspec show` for viewing changes
+- [x] Document how to use git diff for file comparisons
+- [x] Add migration guide to help text or documentation

package.json

@@ -63,7 +63,6 @@
     "@inquirer/prompts": "^7.8.0",
     "chalk": "^5.5.0",
     "commander": "^14.0.0",
-    "jest-diff": "^30.0.5",
     "ora": "^8.2.0",
     "zod": "^4.0.17"
   }