Tell agents about jj and stacked PRs

AGENTS.md

@@ -14,10 +14,38 @@
 - Use the conventions in .prettierrc or run the format command after changes.
 - Avoid adding comments that say obvious things about what the code does.
 - Prefer const-assigned arrow functions over function declarations.
+- Prefer imperative present tense in commit titles and in the parts of commit bodies that say what is changing.
 
 ## Workflow
 
+Check whether the current repo is using Jujutsu (jj) rather than plain git; if so, prefer jj commands for examining
+history and checkpointing your work.
+
 Install new dependencies with `yarn` instead of `npm`.
 
 Format the code, run the typescript checker, and run the linter when you're done working. There's no need to rerun tests
 after code formatting.
+
+## Pull Requests
+
+PR descriptions should focus on why the change was needed and what changed at a high level. Don't talk about choices
+that were considered and ruled out, and don't go into detail about the actual implementation; people can read the code
+diff to see low-level details.
+
+We use stacked pull requests for changes of significant size. Stacks should be organized such that merging the first
+part of the stack still leaves the code base in a working, deployable state. That is, no PR in a stack can leave the
+system nonfunctional.
+
+A stack of PRs should represent a clear, logical sequence of internally-consistent incremental steps that add up to the
+desired goal. It is expected for later PRs in a stack to depend on earlier ones. It's also fine for a PR to include
+small amounts of temporary code that gets rewritten or removed by later PRs, if that helps the earlier PRs stay
+coherent.
+
+When possible, keep each PR in a stack under 350 lines of changes, but only if you can meet the "each PR is a complete
+change that leaves the code base in a working state" goal. 350 lines is a maximum, not a minimum; it's fine to split a
+change into smaller chunks than that.
+
+If the repo is using jj, you can use jj commands to manage the stack of revisions, including splitting, combining, and
+reordering revisions.
+
+Don't push or submit the pull requests yourself; that'll be done manually.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@terraware/web-components",
-  "version": "5.0.25",
+  "version": "5.0.26-rc.0",
   "author": "Terraformation Inc.",
   "license": "Apache-2.0",
   "repository": {