Token crosswalk builder

Builds the backbone artifact of a brownfield retrofit: crosswalk.json, a persistent three-way map of new token ↔ old Figma variable ↔ old code identifier. It drives the code retrofit and the tokens:validate CI gate. This skill also installs the canonical scripts into the user's repo and wires the gate.

This is a brownfield skill. Before doing anything, read ${CLAUDE_PLUGIN_ROOT}/references/brownfield-retrofit.md (read discipline, the 7 guardrails, the safe sequence) and ${CLAUDE_PLUGIN_ROOT}/references/crosswalk-schema.md (the exact contract). Greenfield builds don't need this skill.

Calibrate

Read user.codingLevel (${CLAUDE_PLUGIN_ROOT}/references/coding-level.md) and scale explanation accordingly. The crosswalk involves JSON, npm scripts, and a CI gate — for new users explain each plainly the first time; for comfortable users be terse. Actions are identical across levels.

Prerequisites (offer to run them, don't bail)

Read the manifest. This skill needs:

1. A DTCG token source at packages/tokens/dtcg/tokens.json — the validator resolves against it. If it doesn't exist, offer to run token-sync-layer first (it emits this file). Apply the read discipline: confirm the file exists by reading it, never assume it's absent without looking.
2. The audit inputs — ideally the audit manifest section (code surface, Figma inventory, percentSemantic) populated by design-system-audit. If audit is present, use it to seed the rows. If it is null (audit hasn't run — it lands in Plan 3), don't block: ask the user for the old→new mapping inputs directly (which old Figma variables and code symbols map to which new tokens), and proceed. Note plainly that running design-system-audit first would pre-fill this.
3. A repo at local-git or github (workspace.stage) so the installed scripts and package.json changes land as a reviewable diff/PR. If still folder, offer repository-builder.

Step 1 — Build crosswalk.json

Write packages/tokens/crosswalk.json per the contract in ${CLAUDE_PLUGIN_ROOT}/references/crosswalk-schema.md. One row per new token:

• newToken — the DTCG dot-path exactly as it appears in packages/tokens/dtcg/tokens.json (e.g. color.text.primary).
• newValue — the resolved leaf value (follow {…} aliases to the literal).
• tier — primitive or semantic.
• figmaOld — the old Figma variable name/path, or null if newly added.
• codeTokens[] — the old code identifiers this token replaces ($primary-red, bg-primary-red, Colors.primaryRed, --primary-red). May be [].
• status — aligned | renamed | drift-fix | added | mapped-nearest. Assign by: same name & value → aligned; same value, new name → renamed; value intentionally changed → drift-fix; brand-new token → added; no exact old equivalent, mapped to nearest → mapped-nearest.
• recommendedSemantic — optional semantic target for a raw/primitive usage, else null.

Do not guess values. Every newValue comes from a read of the DTCG source, not an assumption (read discipline).

Step 2 — Install the vetted scripts + wire tokens:validate

Copy these from ${CLAUDE_PLUGIN_ROOT}/scripts/ into the user's repo verbatim (they are zero-dependency and version with the user's repo so their CI can run them):

• lib/crosswalk.mjs → packages/tokens/scripts/lib/crosswalk.mjs
• lib/dtcg.mjs → packages/tokens/scripts/lib/dtcg.mjs (required by validate-crosswalk.mjs — copying the validator without it breaks the gate at import)
• lib/source-scan.mjs → packages/tokens/scripts/lib/source-scan.mjs (required by guard-token-removal.mjs — copying the guard without it breaks it at import)
• validate-crosswalk.mjs → packages/tokens/scripts/validate-crosswalk.mjs
• build-reverse-index.mjs → packages/tokens/scripts/build-reverse-index.mjs
• guard-token-removal.mjs → packages/tokens/scripts/guard-token-removal.mjs
• crosswalk.schema.json → packages/tokens/crosswalk.schema.json (beside crosswalk.json, so the $schema pointer resolves)

Then add to packages/tokens/package.json scripts (don't clobber existing keys):

"tokens:validate": "node scripts/validate-crosswalk.mjs --crosswalk crosswalk.json --tokens dtcg/tokens.json",
"tokens:reverse-index": "node scripts/build-reverse-index.mjs --crosswalk crosswalk.json --out crosswalk.reverse.json"

See ${CLAUDE_PLUGIN_ROOT}/scripts/README.md for the full install contract.

Step 3 — Run the gate (must pass N/N)

Run npm run tokens:validate (from packages/tokens/). It must report N/N — every row's resolved value matches its newValue. If it reports mismatches or missing tokens, fix the crosswalk (or the token source) and re-run. Never proceed on a red validator and never edit a generated token file to make it pass — change the source in Figma and re-sync (guardrail 7). The validator is the source of truth that the crosswalk and the real tokens agree.

Step 4 — Generate the reverse index

Run npm run tokens:reverse-index. This writes crosswalk.reverse.json (codeToken → newToken), which the code-retrofit phase uses to semi-automate the SCSS/Tailwind swaps. If it reports conflicts (one old symbol mapping to two new tokens), resolve them in the crosswalk before relying on the index.

Step 5 — Update the manifest

Write the tokenCrosswalk section only (this skill owns it; never write another skill's fields):

• path — the actual path written ("packages/tokens/crosswalk.json").
• statusCounts — copy the camelCase object the validator printed ({ aligned, renamed, driftFix, added, mappedNearest }).
• validatorPassing — true once tokens:validate passes N/N.

Append token-crosswalk-builder to completedSkills.

What this skill must NOT do

• Never delete old tokens or outputs here — that's the cleanup phase, gated by the token-removal guard returning zero references (safe sequence, guardrail 4).
• Never edit generated token files to make the validator pass — fix the source.
• Never write another skill's manifest fields (e.g. tokens.intakeMode is owned by design-system-audit).
• Never proceed past a red tokens:validate.
• Never assert a prerequisite is absent without a verified read (read discipline).