Add /dld-reindex skill for resolving decision ID collisions

[jimutt]

Summary

Adds a /dld-reindex skill that resolves decision ID collisions between a local branch and the base branch (and open PRs) before rebasing — handling renames, cross-references, annotations, and the history rewrite that a clean rebase requires.

Why a history rewrite

When two developers independently draft DL-NNN decisions under the same ID and one of them merges first, the simple "rename + commit on top" approach doesn't work: git rebase replays commits one at a time and hits an add/add conflict on the original add commit before it ever sees a later rename. The colliding paths must never appear in the branch's history. The skill addresses this by squashing all branch commits since the merge-base into a single reindex commit containing the renamed files. The original commit subjects are preserved in the new commit's body. AskUserQuestion gates the rewrite — the user explicitly chooses Rewrite and force-push / Rewrite only / Cancel.

What the skill does

• plan-renames.sh — single planning step that combines collision detection, the gh-aware "taken IDs" scan (scoped to decisions/records/ so unrelated PRs can't poison it), and free-ID assignment. Emits a deterministic plan: <path>\t<DL-OLD>\t<DL-NEW>.
• rename-decision.sh — git mv preserves rename history; patches the file's id: frontmatter, body self-references, cross-refs in other local decisions (supersedes / amends / references and body), and @decision(DL-OLD) annotations in locally-changed code. Digit-aware substitution (renaming DL-100 won't touch DL-1000). Diffs against the merge-base + working tree so multi-rename runs see uncommitted state from prior calls.
• find-stale-mentions.sh — surfaces bare DL-OLD mentions in code comments / log strings / prose that rename-decision.sh deliberately doesn't auto-rewrite (false-positive risk). The SKILL has the agent review each match in context and decide whether to update it via Edit.
• commit-reindex.sh — mixed-resets to the merge-base, stages an explicit path list (no git add -A, so untracked unrelated paths like .claude/worktrees can never be swept in), and commits. INDEX.md is intentionally excluded from the reindex commit and restored to merge-base state in the working tree — including it caused content conflicts during rebase because git's 3-way merge can't align both sides' top-of-file inserts. An EXIT trap rolls HEAD back if anything fails between the reset and the commit.
• resolve-base.sh — prefers the branch's upstream, falls back to origin/main when the upstream tracks the same branch name (i.e., it's just the remote copy of the local branch, not a useful collision base).
• Post-rebase step: SKILL.md tells the user to run regenerate-index.sh once after git rebase — a small, conflict-free repopulation of INDEX.md with the renamed rows.

gh integration

Opportunistic. If gh isn't installed, the origin isn't a GitHub remote, or gh auth status fails, the PR scan is skipped and a stderr note explains why — surfaced through to the user so they know renamed IDs were chosen against the base branch only.

Files

• skills/dld-reindex/ + .claude/skills/dld-reindex/ — SKILL.md + 7 scripts (resolve-base.sh, plan-renames.sh, find-collisions.sh, list-taken-ids.sh, rename-decision.sh, find-stale-mentions.sh, commit-reindex.sh).
• tile.json — registers the skill, bumps version to 0.7.0.
• rules/dld-workflow.md — adds a one-line bullet pointing at /dld-reindex.
• README.md — Skills table row + "Working in a team" subsection.
• tests/test_reindex.bats — covers collision detection, multi-rename cross-refs, namespaced projects, the recovery trap, the digit-aware edge case, and an end-to-end rebase + post-rebase regenerate.

Test plan

• tests/bats/bin/bats tests/ — 165/165 pass.
• tessl tile lint — clean.
• Real-world dry run with three colliding decisions, body cross-references, base-decision references, @decision annotations across multiple Java files, and a DL-2050-style digit-collision case.

🤖 Generated with Claude Code