name: phase-pr
description: |
Phase-agent wrapper that opens the pull request after implementation
completes (CTL-449 Initiative 1 Phase 3). Delegates to
/catalyst-dev:create-pr (which already auto-runs describe-pr and
transitions Linear to inReview), then writes the PR number + URL into the
phase signal file so the downstream phase-monitor-merge agent can read it
without re-querying GitHub. Dispatched as a claude --bg job by
phase-agent-dispatch, which invokes it via slash command — hence
user-invocable: true.
user-invocable: true
disable-model-invocation: false # invocable by model (Skill tool) AND user (slash command)
allowed-tools:
- Bash
- Read
- Task
phase-pr
Thin wrapper around /catalyst-dev:create-pr. The canonical skill already handles: commit, push,
base-branch detection, PR creation, describe-pr auto-invocation, workflow-context tracking, Linear
inReview transition, and the post-PR resolution loop. Phase-pr adds only the phase-agent envelope
plus persisting pr.number + pr.url to the signal file for phase-monitor-merge.
Prerequisites
CATALYST_ORCHESTRATOR_DIR,CATALYST_ORCHESTRATOR_ID,CATALYST_PHASE=pr,CATALYST_TICKETset by [[phase-agent-dispatch]].- The prior phase's signal file
${ORCH_DIR}/workers/<TICKET>/phase-review.jsonexists withstatus=done— the dispatcher validates this; this skill assumes it. - Current working directory is the ticket's worktree on the implementation branch (not main).
Prelude
set -euo pipefail
: "${CATALYST_ORCHESTRATOR_DIR:?required}"
: "${CATALYST_ORCHESTRATOR_ID:?required}"
: "${CATALYST_PHASE:?required}"
: "${CATALYST_TICKET:?required}"
ORCH_DIR="$CATALYST_ORCHESTRATOR_DIR"
ORCH_ID="$CATALYST_ORCHESTRATOR_ID"
PHASE="$CATALYST_PHASE"
TICKET="$CATALYST_TICKET"
CHANNEL="${ORCH_ID}"
SIGNAL_FILE="${ORCH_DIR}/workers/${TICKET}/phase-${PHASE}.json"
[[ -f "$SIGNAL_FILE" ]] || { echo "phase-${PHASE}: signal file missing" >&2; exit 1; }
PLUGIN_ROOT="${CLAUDE_PLUGIN_ROOT:-}"
[[ -n "$PLUGIN_ROOT" ]] || PLUGIN_ROOT="$(dirname "$(dirname "$(dirname "$(realpath "${BASH_SOURCE[0]:-$0}" 2>/dev/null || echo .)")")")"
COMMS="${PLUGIN_ROOT}/scripts/catalyst-comms"
[[ -x "$COMMS" ]] || COMMS="$(command -v catalyst-comms 2>/dev/null || true)"
if [[ -n "$COMMS" && -x "$COMMS" ]]; then
"$COMMS" join "$CHANNEL" --as "$TICKET" \
--capabilities "phase-pr: ${TICKET}" \
--orch "$ORCH_ID" --parent orchestrator --ttl 3600 >/dev/null 2>&1 || true
"$COMMS" send "$CHANNEL" "phase-pr started" --as "$TICKET" --type info \
--orch "$ORCH_ID" >/dev/null 2>&1 || true
fi
SESSION_SCRIPT="${PLUGIN_ROOT}/scripts/catalyst-session.sh"
if [[ -x "$SESSION_SCRIPT" ]]; then
CATALYST_SESSION_ID=$("$SESSION_SCRIPT" start \
--skill "phase-pr" --ticket "$TICKET" \
--workflow "${CATALYST_SESSION_ID:-}")
export CATALYST_SESSION_ID
fi
TS=$(date -u +%Y-%m-%dT%H:%M:%SZ)
TMP="${SIGNAL_FILE}.tmp.$$"
# CTL-496: persist catalystSessionId so orchestrate-roll-usage --phase can
# attribute cost to the right session_metrics row.
jq --arg ts "$TS" --arg sid "${CATALYST_SESSION_ID:-}" '
.status = "running"
| .updatedAt = $ts
| if $sid != "" then .catalystSessionId = $sid else . end
' "$SIGNAL_FILE" > "$TMP" \
&& mv "$TMP" "$SIGNAL_FILE"
Already-merged detection (CTL-714)
Before delegating to create-pr, detect whether this branch's HEAD is already contained in
origin/main (manual rescue, or a sibling PR landed the same commits). If so, skip PR creation to
avoid a duplicate / empty-diff PR. Two complementary checks: git merge-base --is-ancestor (works
even if the branch was deleted from the remote) and gh pr list --state merged (recovers the merged
PR number for the downstream probe).
The detection fence is side-effect-free so the e2e test can source it in isolation.
git fetch origin main --quiet 2>/dev/null || true
ALREADY_MERGED=0
MERGED_PR_NUMBER=""
MERGED_PR_URL=""
# Check 1: is HEAD already contained in origin/main? (must be in `if` — set -e)
if git merge-base --is-ancestor HEAD origin/main 2>/dev/null; then
ALREADY_MERGED=1
fi
# Check 2: does a MERGED PR exist for this branch? (--state merged is required —
# `gh pr list --head` with no --state returns only OPEN PRs; orchestrate-verify.sh:563)
BRANCH_NAME="$(git branch --show-current 2>/dev/null || true)"
if [[ -n "$BRANCH_NAME" ]]; then
MERGED_PR_JSON="$(gh pr list --head "$BRANCH_NAME" --state merged \
--json number,url --limit 1 2>/dev/null || echo '[]')"
MERGED_PR_NUMBER="$(echo "$MERGED_PR_JSON" | jq -r '.[0].number // empty' 2>/dev/null || true)"
MERGED_PR_URL="$(echo "$MERGED_PR_JSON" | jq -r '.[0].url // empty' 2>/dev/null || true)"
if [[ -n "$MERGED_PR_NUMBER" ]]; then
ALREADY_MERGED=1
fi
fi
When ALREADY_MERGED=1, write the disposition into the signal file and complete without creating a
PR:
if [[ "$ALREADY_MERGED" -eq 1 ]]; then
echo "phase-pr: HEAD already in origin/main — skipping PR creation (CTL-714)" >&2
TS=$(date -u +%Y-%m-%dT%H:%M:%SZ)
TMP="${SIGNAL_FILE}.tmp.$$"
jq --arg ts "$TS" \
--arg reason "already-merged-to-main" \
--argjson prNum "${MERGED_PR_NUMBER:-null}" \
--arg prUrl "${MERGED_PR_URL:-}" '
.updatedAt = $ts
| .attentionReason = $reason
| if $prNum != null then .pr = {number: $prNum, url: $prUrl} else . end
' "$SIGNAL_FILE" > "$TMP" && mv "$TMP" "$SIGNAL_FILE"
"${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \
--phase "$PHASE" --ticket "$TICKET" --status complete
[[ -n "$COMMS" && -x "$COMMS" ]] && "$COMMS" done "$CHANNEL" --as "$TICKET" >/dev/null 2>&1 || true
exit 0
fi
Existing open PR detection (CTL-709)
CTL-709's phase-implement may have already opened a draft PR for this branch. Detect it here so we
can promote it (gh pr ready) rather than re-entering create-pr's interactive "PR already
exists" prompt (create-pr/SKILL.md:96–104) — that prompt would hang a --bg worker forever.
Detection order: merged → existing-open → create-new. The detection fence is side-effect-free so
the e2e test can source it in isolation.
# CTL-709: phase-implement may have already opened a (draft) PR for this branch.
# Detect it here so we can promote it rather than re-entering create-pr's
# interactive "PR already exists" prompt (create-pr/SKILL.md:96 — would hang --bg).
EXISTING_PR_NUMBER=""
EXISTING_PR_URL=""
EXISTING_PR_IS_DRAFT=""
EXISTING_PR_JSON="$(gh pr view --json number,url,state,isDraft 2>/dev/null || true)"
if [[ -n "$EXISTING_PR_JSON" ]]; then
if [[ "$(printf '%s' "$EXISTING_PR_JSON" | jq -r '.state // empty' 2>/dev/null)" == "OPEN" ]]; then
EXISTING_PR_NUMBER="$(printf '%s' "$EXISTING_PR_JSON" | jq -r '.number // empty' 2>/dev/null || true)"
EXISTING_PR_URL="$(printf '%s' "$EXISTING_PR_JSON" | jq -r '.url // empty' 2>/dev/null || true)"
EXISTING_PR_IS_DRAFT="$(printf '%s' "$EXISTING_PR_JSON" | jq -r '.isDraft // false' 2>/dev/null || true)"
fi
fi
When an existing open PR is found, promote it (if draft) and finish — without delegating to
create-pr. The promote-and-finish block is NOT side-effect-free.
# CTL-864: cross-host fence — bow out if a takeover superseded us. No-op single-host.
"${PLUGIN_ROOT}/scripts/lib/cluster-fence-guard.sh" --phase "$PHASE" --ticket "$TICKET" || exit 10
if [[ -n "$EXISTING_PR_NUMBER" ]]; then
echo "phase-pr: promoting existing PR #${EXISTING_PR_NUMBER} (draft=${EXISTING_PR_IS_DRAFT})" >&2
if [[ -r "${PLUGIN_ROOT}/scripts/lib/draft-pr.sh" ]]; then
# shellcheck source=/dev/null
source "${PLUGIN_ROOT}/scripts/lib/draft-pr.sh"
fi
# CTL-1051: prove the remote branch (and the PR head) equal the worktree HEAD
# BEFORE announcing the promoted PR — remediation/rebase may have advanced
# local HEAD past the draft's pushed commit. Fail-closed: a stale ref is a
# phase FAILURE, not a silent complete.
# CTL-1119: rc=3 from draft_pr_push_verify means the push was rejected for
# missing 'workflow' OAuth scope; escalate with an actionable human_question.
VERIFIED_SHA=""
PUSH_VERIFY_RC=0
# CTL-1119 remediate: capture stdout ONLY (the verified SHA). draft_pr_push_verify
# writes diagnostic _draft_pr_warn lines to stderr on every retry path (force-with-lease
# AND the token-routed push); folding them in with 2>&1 made VERIFIED_SHA multi-line, so
# the PR_HEAD_OID != VERIFIED_SHA guard below always tripped and falsely failed the phase
# with stale_ref_push_verify_failed. No redirect: stderr flows to the worker log.
VERIFIED_SHA="$(draft_pr_push_verify)" || PUSH_VERIFY_RC=$?
if [[ "$PUSH_VERIFY_RC" -eq 3 ]]; then
echo "phase-pr: push rejected — missing 'workflow' OAuth scope on existing PR path" >&2
if [[ -r "${PLUGIN_ROOT}/scripts/lib/escalate-workflow-scope.sh" ]]; then
# shellcheck source=/dev/null
source "${PLUGIN_ROOT}/scripts/lib/escalate-workflow-scope.sh"
_escalate_workflow_scope_push
else
"${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \
--phase "$PHASE" --ticket "$TICKET" --status failed \
--reason "push_rejected_no_workflow_scope"
fi
exit 1
elif [[ "$PUSH_VERIFY_RC" -ne 0 ]]; then
echo "phase-pr: push-verify failed for #${EXISTING_PR_NUMBER} (stale ref)" >&2
"${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \
--phase "$PHASE" --ticket "$TICKET" --status failed \
--reason "stale_ref_push_verify_failed"
exit 1
fi
PR_HEAD_OID="$(draft_pr_head_oid || true)"
if [[ -n "$PR_HEAD_OID" && "$PR_HEAD_OID" != "$VERIFIED_SHA" ]]; then
echo "phase-pr: PR headRefOid ${PR_HEAD_OID} != worktree HEAD ${VERIFIED_SHA}" >&2
"${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \
--phase "$PHASE" --ticket "$TICKET" --status failed \
--reason "stale_ref_push_verify_failed"
exit 1
fi
if [[ "$EXISTING_PR_IS_DRAFT" == "true" ]]; then
if type draft_pr_promote >/dev/null 2>&1; then
draft_pr_promote || gh pr ready "$EXISTING_PR_NUMBER" 2>/dev/null || true
else
gh pr ready "$EXISTING_PR_NUMBER" 2>/dev/null || true
fi
fi
# Enrich the PR body now that the draft is ready (deferred from phase-implement to keep
# its End block free of Task-tool calls — research Q4).
#
# Use the Task tool to invoke /catalyst-dev:describe-pr on $EXISTING_PR_NUMBER.
# describe-pr is non-interactive when CATALYST_PHASE is set (it skips the Linear
# inReview transition — the coordinator owns that — create-pr/SKILL.md:226–232).
TS2=$(date -u +%Y-%m-%dT%H:%M:%SZ)
TMP="${SIGNAL_FILE}.tmp.$$"
jq --argjson pr "$EXISTING_PR_NUMBER" --arg url "$EXISTING_PR_URL" --arg ts "$TS2" \
'.pr={number:$pr,url:$url} | .updatedAt=$ts' \
"$SIGNAL_FILE" > "$TMP" && mv "$TMP" "$SIGNAL_FILE"
echo "phase-pr: existing PR #${EXISTING_PR_NUMBER} promoted — skipping create-pr delegation" >&2
fi
/goal condition
Plan §"Per-phase /goal conditions":
/goal "`gh pr view --json number,state,headRefName` shows an open PR linked
to ${TICKET} AND Linear state is `In Review` AND describe-pr has run
successfully (I have printed the PR URL and `describe-pr ran` to my
transcript)."
Turn cap defaults to 12 (from phase-agent-dispatch:phase_default_turn_cap). This is intentionally
tight because the work is mostly tool calls — most of the reasoning happens upstream in create-pr
itself.
Phase-specific work
When
EXISTING_PR_NUMBERis set (the draft opened byphase-implementwas detected and promoted above): invoke/catalyst-dev:describe-prvia the Task tool on$EXISTING_PR_NUMBER. Then proceed directly to the End block — do not invoke/catalyst-dev:create-pr.When
EXISTING_PR_NUMBERis empty (Phase 3 draft creation failed or was disabled): invoke/catalyst-dev:create-prvia the Task tool. The canonical skill handles: branch push, base-branch resolution, idempotent PR creation if one already exists,describe-prinvocation, and LinearinReviewtransition.After either path, capture the PR metadata via
ghand write it into the phase signal file sophase-monitor-mergecan read it directly without re-querying GitHub. For the create-pr path, push-verify before recording metadata (CTL-1051):# CTL-1051: ensure create-pr's push left origin == HEAD and the PR points at it. # CTL-1119: rc=3 means the push was rejected for missing 'workflow' OAuth scope. [[ -r "${PLUGIN_ROOT}/scripts/lib/draft-pr.sh" ]] && source "${PLUGIN_ROOT}/scripts/lib/draft-pr.sh" VERIFIED_SHA="" PUSH_VERIFY_RC=0 # CTL-1119 remediate: capture stdout ONLY (the verified SHA) — see the existing-PR path # above. 2>&1 folded draft_pr_push_verify's stderr warnings into VERIFIED_SHA on retry # paths, breaking the PR_HEAD_OID comparison with a false stale_ref_push_verify_failed. VERIFIED_SHA="$(draft_pr_push_verify)" || PUSH_VERIFY_RC=$? if [[ "$PUSH_VERIFY_RC" -eq 3 ]]; then echo "phase-pr: push rejected — missing 'workflow' OAuth scope on create-pr path" >&2 if [[ -r "${PLUGIN_ROOT}/scripts/lib/escalate-workflow-scope.sh" ]]; then # shellcheck source=/dev/null source "${PLUGIN_ROOT}/scripts/lib/escalate-workflow-scope.sh" _escalate_workflow_scope_push else "${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \ --phase "$PHASE" --ticket "$TICKET" --status failed \ --reason "push_rejected_no_workflow_scope" fi exit 1 elif [[ "$PUSH_VERIFY_RC" -ne 0 ]]; then echo "phase-pr: post-create-pr push-verify failed (stale ref)" >&2 "${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \ --phase "$PHASE" --ticket "$TICKET" --status failed \ --reason "stale_ref_push_verify_failed" exit 1 fi PR_HEAD_OID="$(draft_pr_head_oid || true)" if [[ -n "$PR_HEAD_OID" && "$PR_HEAD_OID" != "$VERIFIED_SHA" ]]; then echo "phase-pr: PR headRefOid ${PR_HEAD_OID} != HEAD ${VERIFIED_SHA}" >&2 "${PLUGIN_ROOT}/scripts/phase-agent-emit-complete" \ --phase "$PHASE" --ticket "$TICKET" --status failed \ --reason "stale_ref_push_verify_failed" exit 1 fi PR_INFO=$(gh pr view --json number,url,headRefName,baseRefName 2>/dev/null || echo "{}") PR_NUMBER=$(echo "$PR_INFO" | jq -r '.number // empty') PR_URL=$(echo "$PR_INFO" | jq -r '.url // empty') if [[ -n "$PR_NUMBER" ]]; then TS2=$(date -u +%Y-%m-%dT%H:%M:%SZ) TMP="${SIGNAL_FILE}.tmp.$$" jq --argjson pr "$PR_NUMBER" --arg url "$PR_URL" --arg ts "$TS2" \ '.pr = {number: $pr, url: $url} | .updatedAt = $ts' \ "$SIGNAL_FILE" > "$TMP" && mv "$TMP" "$SIGNAL_FILE" echo "phase-pr: opened PR #${PR_NUMBER} at ${PR_URL}" else echo "phase-pr: gh pr view returned no PR — create-pr may have failed" >&2 fiThe post-PR active resolution loop (CI fix-up, bot review threads, BEHIND rebase) is not run here — that is
phase-monitor-merge's responsibility.create-pr's own brief monitoring window stays insidecreate-pr; phase-pr exits as soon as the PR exists inOPENstate.
End block
Mirror the phase output to Linear as a single comment (CTL-632). Describes the PR that was opened
(number, URL, title, files changed, additions/deletions, commit count) plus the pre-merge
verification surfaced from the verify phase's verify.json (test/typecheck/lint gate status +
regression risk) so the trail records what was checked before the PR went up. PR metadata is re-read
from the phase signal file (.pr.number/.pr.url, written in the phase-specific work above) and
enriched via gh pr view; the verify summary is fail-soft if no verify.json exists. Body
hard-truncated to 30,000 bytes. Fail-open and idempotent via the per-phase marker file.
Uniquely-named fence so the e2e test can extract just this block.
LINEAR_MIRROR_MARKER="${ORCH_DIR}/workers/${TICKET}/.linear-mirror-${PHASE}"
if [[ ! -e "${LINEAR_MIRROR_MARKER}" ]]; then
PR_SIGNAL="${ORCH_DIR}/workers/${TICKET}/phase-${PHASE}.json"
PR_NUMBER="$(jq -r '.pr.number // empty' "${PR_SIGNAL}" 2>/dev/null || true)"
PR_URL="$(jq -r '.pr.url // empty' "${PR_SIGNAL}" 2>/dev/null || true)"
PR_VIEW="{}"
if [[ -n "${PR_NUMBER}" ]]; then
PR_VIEW="$(gh pr view "${PR_NUMBER}" --json title,files,additions,deletions,commits 2>/dev/null || echo '{}')"
fi
PR_TITLE="$(printf '%s' "${PR_VIEW}" | jq -r '.title // "_untitled_"' 2>/dev/null || echo '_untitled_')"
FILES_CHANGED="$(printf '%s' "${PR_VIEW}" | jq -r '(.files // []) | length' 2>/dev/null || echo '?')"
ADDITIONS="$(printf '%s' "${PR_VIEW}" | jq -r '.additions // "?"' 2>/dev/null || echo '?')"
DELETIONS="$(printf '%s' "${PR_VIEW}" | jq -r '.deletions // "?"' 2>/dev/null || echo '?')"
COMMIT_COUNT="$(printf '%s' "${PR_VIEW}" | jq -r '(.commits // []) | length' 2>/dev/null || echo '?')"
VERIFY_JSON_FILE="${ORCH_DIR}/workers/${TICKET}/verify.json"
VERIFY_RENDERED="_no verify.json found — verification ran in a prior phase or was skipped_"
if [[ -f "${VERIFY_JSON_FILE}" ]]; then
VERIFY_RENDERED="$(jq -r '
("- **Regression risk**: " + ((.regression_risk // "?")|tostring) + " / 10")
+ "\n"
+ ((.gates // {})
| to_entries
| map(select(.key | test("test|typecheck|lint|coverage")))
| map("- **" + .key + "**: " + (.value.status // "unknown")
+ (if .value.summary then " — " + .value.summary else "" end))
| join("\n"))
' "${VERIFY_JSON_FILE}" 2>/dev/null || echo '_verify.json unreadable_')"
fi
MIRROR_BODY="$(cat <<EOF
**Phase PR** — opened PR #${PR_NUMBER:-?}
- **PR**: ${PR_URL:-_url unavailable_}
- **Title**: ${PR_TITLE}
- **Files changed**: ${FILES_CHANGED} (+${ADDITIONS} / -${DELETIONS})
- **Commits**: ${COMMIT_COUNT}
**Pre-merge verification** (from the verify phase):
${VERIFY_RENDERED}
_Posted automatically by phase-pr (CTL-632)._
EOF
)"
MIRROR_FOOTER=""
if [[ -n "${PLUGIN_ROOT:-}" && -x "${PLUGIN_ROOT}/scripts/lib/phase-mirror-footer.sh" ]]; then
MIRROR_FOOTER="$("${PLUGIN_ROOT}/scripts/lib/phase-mirror-footer.sh" --orch-dir "${ORCH_DIR}" --ticket "${TICKET}" --phase "${PHASE}" 2>/dev/null || true)"
fi
[[ -n "${MIRROR_FOOTER}" ]] && MIRROR_BODY="${MIRROR_BODY}
${MIRROR_FOOTER}"
if [[ ${#MIRROR_BODY} -gt 30000 ]]; then
MIRROR_BODY="${MIRROR_BODY:0:30000}
_... (truncated)_"
fi
COMMENT_POST="${CATALYST_COMMENT_POST_HELPER:-${PLUGIN_ROOT}/scripts/lib/linear-comment-post.sh}"
if [[ ! -x "$COMMENT_POST" ]]; then COMMENT_POST="$(command -v linear-comment-post.sh 2>/dev/null || true)"; fi
if [[ -n "$COMMENT_POST" && -x "$COMMENT_POST" ]] && "$COMMENT_POST" "${TICKET}" "${MIRROR_BODY}" >/dev/null; then
: > "${LINEAR_MIRROR_MARKER}"
else
echo "phase-pr: linear-comment-post failed (continuing)" >&2
fi
fi
EMIT="${PLUGIN_ROOT}/scripts/phase-agent-emit-complete"
if [[ -x "$EMIT" ]]; then
"$EMIT" --phase "$PHASE" --ticket "$TICKET" --status complete
fi
# Self-halt after complete to prevent zombie workers (CTL-778 step 2).
# Read our own bg_job_id from the signal file and ask Claude to stop us.
# Best-effort: a failed stop is covered by the daemon reaper backstop.
if [[ -n "${ORCH_DIR:-}" && -f "${ORCH_DIR}/workers/${TICKET}/phase-${PHASE}.json" ]]; then
_SELF_BG=$(jq -r '.bg_job_id // empty' \
"${ORCH_DIR}/workers/${TICKET}/phase-${PHASE}.json" 2>/dev/null || true)
[[ -n "$_SELF_BG" ]] && claude stop "${_SELF_BG:0:8}" >/dev/null 2>&1 || true
fi
[[ -n "$COMMS" && -x "$COMMS" ]] && "$COMMS" done "$CHANNEL" --as "$TICKET" >/dev/null 2>&1 || true
Failure handling
REASON="${1:-create-pr exited non-zero}"
"$EMIT" --phase "$PHASE" --ticket "$TICKET" --status failed --reason "$REASON"
[[ -n "$COMMS" && -x "$COMMS" ]] && "$COMMS" send "$CHANNEL" \
"phase-pr failed: ${REASON}" \
--as "$TICKET" --type attention --orch "$ORCH_ID" >/dev/null 2>&1 || true
exit 1
Common failure modes:
- Branch not pushable (e.g., diverged, network failure):
create-prerrors; phase-pr emitsfailedwith the underlying reason. - PR already exists with no new commits: not a failure —
create-pris idempotent and returns the existing PR. The signal file gets the existing PR number written, downstream phases proceed normally. ghnot authenticated: emitfailedwith the gh stderr; orchestrator's retry path will not unstick this — escalate viaattention.
Why this is a thin wrapper
Plan architectural commitment #3. /catalyst-dev:create-pr is mature (504 lines as of CTL-373) and
owns workflow-context, Linear linking, describe-pr, and idempotency. phase-pr adds the phase-agent
envelope (~80 lines) and nothing else — improvements to create-pr propagate for free.