fix(#4830): re-land #4768's letter-suffix phase-id fix and its lint-phase-id-drift ratchets on current next (#4873)

* fix(#4830): re-land #4768's letter-suffix phase-id fix and its lint-phase-id-drift ratchets on current next

Commit 740ba0d8a (#4781) removed every change #4768 had merged for #4748:
the first-non-digit split at execute-phase.md's two arithmetic sites, the
init-emitted `padded_phase` the REVIEW.md lookup binds instead of
`printf "%02d"`, the canonical-grammar extractions in autonomous.md and
plan-review-convergence.md, the `.changeset/zesty-wolves-tumble.md`
fragment, and the three lint-phase-id-drift ratchets with their tests.
The guard and the code it guarded left together, so nothing went red.

This is a cherry-pick of 092d9256b onto current `next`, resolved against
the #4683 threat-id fields on execute-phase.md's Parse-JSON line, with the
changeset `pr:` reset to the placeholder and the compact-content benchmark
baseline regenerated against the current base.

(cherry picked from commit 092d9256b8)

Emitted-Drift-Ack-Growth: autonomous.md — restores #4768's canonical-grammar extraction and its explanatory comment for --from/--to/--only
Emitted-Drift-Ack-Growth: execute-phase.md — restores #4768's first-non-digit split at two arithmetic sites and the padded_phase binding for the REVIEW.md lookup
Emitted-Drift-Ack-Growth: plan-review-convergence.md — restores #4768's canonical-grammar phase extraction and its comment
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AX7LXxc3uAkGki6iaYiAMP

* chore(#4830): set changeset fragment pr to 4873

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: Tom Boucher <trekkie@nomorestars.com>

gsd-core/workflows/execute-phase.md

@@ -92,7 +92,7 @@ if [[ "$INIT" == @file:* ]]; then INIT=$(cat "${INIT#@file:}"); fi
 AGENT_SKILLS=$(gsd_run query agent-skills gsd-executor)
 ```
 
-Parse JSON for: `executor_model`, `verifier_model`, `commit_docs`, `parallelization`, `branching_strategy`, `branch_name`, `phase_found`, `phase_dir`, `phase_number`, `phase_name`, `phase_slug`, `plans`, `incomplete_plans`, `plan_count`, `incomplete_count`, `state_exists`, `roadmap_exists`, `phase_req_ids`, `response_language`, `requirements_path`, `section_manifest`, `threat_id_duplicate_count`.
+Parse JSON for: `executor_model`, `verifier_model`, `commit_docs`, `parallelization`, `branching_strategy`, `branch_name`, `phase_found`, `phase_dir`, `phase_number`, `padded_phase`, `phase_name`, `phase_slug`, `plans`, `incomplete_plans`, `plan_count`, `incomplete_count`, `state_exists`, `roadmap_exists`, `phase_req_ids`, `response_language`, `requirements_path`, `section_manifest`, `threat_id_duplicate_count`.
 
 **Threat-ID gate (#4683):** if `threat_id_duplicate_count` is non-zero, read and execute `execute-phase/steps/threat-id-gate.md` BEFORE any dispatch — it is a hard stop (the full duplicate list is in `threat_id_duplicates`).
 
@@ -196,8 +196,11 @@ PHASE_NUMBER="{phase_number}"
 # #4619: {phase_number} may be decimal (01.1) or N-segment (23.1.2) — $((10#...))
 # is a hard shell syntax error on a non-integer, so zero-strip only the LEADING
 # integer segment and keep the rest as an escaped-dot string for the ERE below.
-PHASE_INT=${PHASE_NUMBER%%.*}; PHASE_FRAC=${PHASE_NUMBER#"$PHASE_INT"}
-PHASE_N="$((10#$PHASE_INT))${PHASE_FRAC//./\\.}"
+# #4748: it may also carry a letter suffix (03A, 23A.1.2 — the canonical grammar
+# is digits, optional [A-Z], dotted segments), so split at the first NON-DIGIT,
+# not the first dot: the letter rides along in the rest, unescaped.
+PHASE_INT=${PHASE_NUMBER%%[!0-9]*}; PHASE_REST=${PHASE_NUMBER#"$PHASE_INT"}
+PHASE_N="$((10#$PHASE_INT))${PHASE_REST//./\\.}"
 PLAN_N=$((10#{plan_padded}))
 PLAN_SCOPE_RE="^[a-z]+\((0*${PHASE_N})-(0*${PLAN_N})\):"
 MILESTONE_BASE=$(git describe --tags --abbrev=0 2>/dev/null || echo "")
@@ -219,9 +222,10 @@ if [ "$TDD_MODE" = "true" ]; then
     # #4003: same anchored scope and milestone bound as safe_resume_gate — a padded
     # literal grep hard-halts on a correct unpadded RED commit.
     # #4619: PHASE_NUMBER may be decimal/N-segment; zero-strip only the leading
-    # integer segment, escape the rest for the ERE below.
-    PHASE_INT=${PHASE_NUMBER%%.*}; PHASE_FRAC=${PHASE_NUMBER#"$PHASE_INT"}
-    PHASE_N="$((10#$PHASE_INT))${PHASE_FRAC//./\\.}"
+    # integer segment, escape the rest for the ERE below. #4748: it may carry a
+    # letter suffix (03A), so the split is at the first non-digit, not the dot.
+    PHASE_INT=${PHASE_NUMBER%%[!0-9]*}; PHASE_REST=${PHASE_NUMBER#"$PHASE_INT"}
+    PHASE_N="$((10#$PHASE_INT))${PHASE_REST//./\\.}"
     PLAN_N=$((10#${PLAN_ID}))
     PLAN_SCOPE_RE="^[a-z]+\((0*${PHASE_N})-(0*${PLAN_N})\):"  # TDD gate's own scope check
     TDD_MILESTONE_BASE=$(git describe --tags --abbrev=0 2>/dev/null || echo "")
@@ -1159,7 +1163,9 @@ Skill(skill="gsd-${ref.skill}", args="${PHASE_NUMBER}")
 
 **Check results using deterministic path (not glob):**
 ```bash
-PADDED=$(printf "%02d" "${PHASE_NUMBER}")
+# #4748: bind init's normalized id — `printf "%02d"` cannot pad a letter id
+# (03A → `03`, exit 1) and reads an already-padded `08` as octal (→ `00`).
+PADDED="{padded_phase}"
 REVIEW_FILE="${PHASE_DIR}/${PADDED}-REVIEW.md"
 REVIEW_STATUS=$(sed -n '/^---$/,/^---$/p' "$REVIEW_FILE" | grep "^status:" | head -1 | cut -d: -f2 | tr -d ' ')
 ```