opsx-diff

OpenSpec project root. The openspec/ directory lives in the REPO, not the workspace this skill is driven from. The repo root is ${SPECRAILS_REPO_DIR:-.} (a default-unset env var: when unset it resolves to ., i.e. the current directory, so a classic in-repo run is unchanged). Run EVERY openspec command against that root — wrap each invocation as (cd "${SPECRAILS_REPO_DIR:-.}" && openspec …). Treat ${SPECRAILS_REPO_DIR:-.} as the OpenSpec project root for any path the CLI prints or you read/write.

Visualize spec changes for this project (read name from CLAUDE.md or package.json): compare the current specs against a named OpenSpec change to show exactly what behavioral requirements are being added, modified, or removed.

Input: $ARGUMENTS — accepts:

• <change-name> — the kebab-case name of the change to diff (required). If omitted, interactive selection is offered.
• --format json — emit structured JSON instead of markdown (default: markdown).
• --summary-only — skip inline line-level diff; show only the file-level and behavioral summary.

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Phase 0: Argument Parsing

Parse $ARGUMENTS to set runtime variables.

Variables to set:

• CHANGE_NAME — string. Required. If not provided, prompt the user.
• FORMAT — "markdown" or "json". Default: "markdown".
• SUMMARY_ONLY — boolean. Default: false.

Parsing rules:

1. Scan $ARGUMENTS for --format <value>. If found and value is json, set FORMAT="json". Any other value: print Error: unknown format "<value>". Valid: markdown, json and stop. Strip from arguments.
2. Scan for --summary-only. If found, set SUMMARY_ONLY=true. Strip from arguments.
3. Treat the remaining token (if any) as CHANGE_NAME. Strip leading/trailing whitespace.
4. If CHANGE_NAME is empty after parsing:
   • Run:

     (cd "${SPECRAILS_REPO_DIR:-.}" && openspec list --json)
     

   • If the result shows available changes, use the AskUserQuestion tool (open-ended, show the list) to ask which change to diff.
   • If no changes exist, print:

     Error: no active changes found. Run /opsx:new or /opsx:ff to create one first.
     

     Stop.

Print active configuration:

Diffing change: <CHANGE_NAME>
Format: <markdown|json>
Summary only: <yes|no>

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