feat(skills): propose /opsx:update planning-artifact update skill

docs/commands.md

@@ -13,6 +13,7 @@ For workflow patterns and when to use each command, see [Workflows](workflows.md
 | `/opsx:propose` | Create a change and generate planning artifacts in one step |
 | `/opsx:explore` | Think through ideas before committing to a change |
 | `/opsx:apply` | Implement tasks from the change |
+| `/opsx:update` | Revise a change's planning artifacts and keep them coherent |
 | `/opsx:sync` | Merge delta specs into main specs |
 | `/opsx:archive` | Archive a completed change |
 
@@ -317,6 +318,50 @@ AI:  Implementing add-dark-mode...
 
 ---
 
+### `/opsx:update`
+
+Revise a change's existing planning artifacts and keep them coherent with one another. Planning artifacts only - it never edits code.
+
+**Syntax:**
+```
+/opsx:update [change-name]
+```
+
+**Arguments:**
+| Argument | Required | Description |
+|----------|----------|-------------|
+| `change-name` | No | Which change to update (inferred from context if not provided) |
+
+**What it does:**
+- Reads the change's artifacts via `openspec status --change <name> --json`
+- Applies your requested revision, or reviews the artifacts for contradictions if you didn't name one
+- Reconciles the other existing artifacts in any direction (a design edit may ripple back to the proposal)
+- Confirms every edit with you before writing, one artifact at a time
+- Ends by recommending the next step: `/opsx:continue` (artifacts missing), `/opsx:apply` (carry a revised plan into code), or `/opsx:archive` (all done)
+
+**Example:**
+```
+You: /opsx:update add-dark-mode - we're storing the theme in a cookie now, not localStorage
+
+AI:  Reading add-dark-mode artifacts...
+
+     The design references localStorage in two places; tasks 1.3 covers
+     localStorage persistence; the proposal doesn't mention storage.
+
+     Proposed revisions:
+     1. design.md - swap localStorage decision for cookie storage
+     2. tasks.md - reword task 1.3 to cookie persistence
+
+     Apply revision 1? (design.md)
+```
+
+**Tips:**
+- It won't create missing artifacts - that's `/opsx:continue`
+- If the change was already implemented, follow up with `/opsx:apply` so the code matches the revised plan
+- If your revision changes the *intent* of the change, start fresh with a new change instead (see [When to Update vs. Start Fresh](opsx.md#when-to-update-vs-start-fresh))
+
+---
+
 ### `/opsx:verify`
 
 Validate that implementation matches your change artifacts. Checks completeness, correctness, and coherence.

docs/opsx.md

@@ -163,6 +163,7 @@ rules:
 | `/opsx:continue` | Create the next artifact (expanded workflow) |
 | `/opsx:ff` | Fast-forward planning artifacts (expanded workflow) |
 | `/opsx:apply` | Implement tasks, updating artifacts as needed |
+| `/opsx:update` | Revise a change's planning artifacts and keep them coherent |
 | `/opsx:verify` | Validate implementation against artifacts (expanded workflow) |
 | `/opsx:sync` | Sync delta specs to main (default workflow, optional) |
 | `/opsx:archive` | Archive when done |
@@ -208,6 +209,12 @@ Creates all planning artifacts at once. Use when you have a clear picture of wha
 ```
 Works through tasks, checking them off as you go. If you're juggling multiple changes, you can run `/opsx:apply <name>`; otherwise it should infer from the conversation and prompt you to choose if it can't tell.
 
+### Updating a change
+```
+/opsx:update add-dark-mode - we're storing the theme in a cookie now
+```
+Revises the change's existing planning artifacts and keeps them coherent - in any direction (a design edit may ripple back to the proposal). Planning artifacts only: it never edits code, and it never creates missing artifacts (that's `/opsx:continue`). Every edit is confirmed with you first. If the change was already implemented, it recommends `/opsx:apply` so the code catches up with the revised plan. If your revision changes the change's *intent*, start fresh instead - see [When to Update vs. Start Fresh](#when-to-update-vs-start-fresh).
+
 ### Finish up
 ```
 /opsx:archive   # Move to archive when done (prompts to sync specs if needed)

docs/supported-tools.md

@@ -96,6 +96,7 @@ When selected by profile/workflow config, OpenSpec generates these skills:
 - `openspec-new-change`
 - `openspec-continue-change`
 - `openspec-apply-change`
+- `openspec-update-change`
 - `openspec-ff-change`
 - `openspec-sync-specs`
 - `openspec-archive-change`

openspec/changes/add-update-workflow/.openspec.yaml

@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-06-29