fix: resolve conflicts for PR #422

Merge prgs/master; keep review workflow load gate (#403) with explicit
merge_pr preflight task binding.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

skills/llm-project-workflow/workflows/review-merge-pr.md

@@ -664,6 +664,28 @@ Do not claim “full-suite failures are pre-existing” unless baseline proof is
 
 ## 23. Validation command proof rule
 
+Before any diff, test, or compile validation, record in the same command
+transcript or final report:
+
+* `pwd` or explicit working directory
+* `git rev-parse HEAD`
+* `git status --short --branch`
+* expected PR head SHA (candidate head SHA)
+
+Validation commands must use one of:
+
+* `git -C <review_worktree> ...`
+* `cd <review_worktree> && ...` in the same command
+* tool-provided explicit working-directory metadata
+
+Do not rely on inferred shell cwd from a prior command in a different block.
+
+`gitea_validate_review_final_report` rejects validation claims without
+cwd/HEAD proof when `validation_session` is supplied.
+
+Baseline validation must document baseline worktree path, baseline target SHA,
+cwd proof, exact baseline command, and baseline result using the same rules.
+
 Report the exact validation command as executed.
 
 Report the working directory where validation ran.
@@ -1227,6 +1249,7 @@ Controller Handoff:
 * Files reviewed:
 * Validation:
 * Validation failure history:
+* Validation cwd/HEAD proof:
 * Official validation integrity status:
 * Terminal review mutation:
 * Review decision:

skills/llm-project-workflow/workflows/work-issue.md

@@ -144,6 +144,14 @@ If the main checkout is dirty before selection, stop and produce a recovery hand
 
 If the main checkout becomes dirty during the run, stop and produce a recovery handoff unless the change is explicitly allowed by the canonical workflow.
 
+### Stacked PRs (explicit exception, #484)
+
+Normal author work stays base-equivalent to `master`/`main`/`dev`. A **stacked PR** — deliberately based on another unmerged PR's branch — is the only sanctioned non-master base, and only when the operator/controller explicitly chooses it:
+
+- Branch the `branches/` worktree from the dependency's branch, then lock with `gitea_lock_issue(..., stacked_base_branch=<dep-branch>, stacked_base_pr=<open-PR#>)`. The lock fails closed unless that open PR owns the branch; arbitrary or stale branches are rejected.
+- Open the PR with `gitea_create_pr(base=<dep-branch>)`. The body must state: `Stacked on PR #<X> / issue #<Y>`, `Base branch: <dep-branch>`, `Head branch: <this-branch>`, `Do not merge before PR #<X>`, and note retarget/rebase to `master` after the dependency lands if required.
+- This does not relax the main-checkout rule or bypass the issue lock — work still happens under `branches/`, and the approved base is recorded on the lock.
+
 ## 5. No raw MCP repair during normal issue work
 
 Do not run `pkill`, kill MCP processes, edit MCP config, restart servers, or perform control-checkout repair during normal issue work.