diff --git a/internal/scaffold/fullsend-repo/scripts/post-code.sh b/internal/scaffold/fullsend-repo/scripts/post-code.sh
index c6e839ab18..aa05898ff6 100755
--- a/internal/scaffold/fullsend-repo/scripts/post-code.sh
+++ b/internal/scaffold/fullsend-repo/scripts/post-code.sh
@@ -48,7 +48,7 @@ REPO_DIR="${REPO_DIR:-repo}"
 
 if [ "${REPO_DIR}" != "." ]; then
   if [ ! -d "${REPO_DIR}" ]; then
-    echo "::error::Extracted repo not found at ${REPO_DIR}"
+    echo "::error::Extracted repo not found at ${REPO_DIR}" >&2
     exit 1
   fi
   cd "${REPO_DIR}"
@@ -215,9 +215,9 @@ echo "Secret scan passed — no leaks in agent's commit(s)"
 # ---------------------------------------------------------------------------
 echo "Checking for Signed-off-by trailers in agent's commit(s)..."
 if git log --format='%b' "${SCAN_RANGE}" | grep -q '^Signed-off-by:'; then
-  echo "::error::BLOCKED — agent commit contains a Signed-off-by trailer"
-  echo "::error::Agents must not use 'git commit -s' or append Signed-off-by trailers."
-  echo "::error::DCO is a human attestation; the DCO app waives the check for bots."
+  echo "::error::BLOCKED — agent commit contains a Signed-off-by trailer" >&2
+  echo "::error::Agents must not use 'git commit -s' or append Signed-off-by trailers." >&2
+  echo "::error::DCO is a human attestation; the DCO app waives the check for bots." >&2
   exit 1
 fi
 echo "Signed-off-by scan passed — no trailers in agent's commit(s)"
@@ -231,7 +231,7 @@ if ! command -v lychee >/dev/null 2>&1; then
   case "$(uname -m)" in
     x86_64)  LY_TRIPLE="x86_64-unknown-linux-gnu";  LY_SHA="${LYCHEE_SHA256_AMD64}" ;;
     aarch64) LY_TRIPLE="aarch64-unknown-linux-gnu"; LY_SHA="${LYCHEE_SHA256_ARM64}" ;;
-    *) echo "::error::Unsupported architecture for lychee: $(uname -m)"; exit 1 ;;
+    *) echo "::error::Unsupported architecture for lychee: $(uname -m)" >&2; exit 1 ;;
   esac
   curl -fsSL \
     "https://github.com/lycheeverse/lychee/releases/download/lychee-v${LYCHEE_VERSION}/lychee-${LY_TRIPLE}.tar.gz" \
@@ -279,9 +279,9 @@ if [ -f .pre-commit-config.yaml ]; then
     if pre-commit run --files "${changed_array[@]}"; then
       echo "Pre-commit passed — all hooks clean"
     else
-      echo "::error::BLOCKED — pre-commit hooks failed on agent's changes"
-      echo "::error::The agent's code does not pass the repo's pre-commit hooks."
-      echo "::error::Fix the issues and re-run, or update the pre-commit config."
+      echo "::error::BLOCKED — pre-commit hooks failed on agent's changes" >&2
+      echo "::error::The agent's code does not pass the repo's pre-commit hooks." >&2
+      echo "::error::Fix the issues and re-run, or update the pre-commit config." >&2
       exit 1
     fi
   else
@@ -334,7 +334,8 @@ if [ "${PUSH_RC}" -ne 0 ]; then
     echo "::warning::Plain push failed (non-fast-forward) — retrying with --force-with-lease"
     git push --force-with-lease -u origin -- "${BRANCH}" 2>&1
   else
-    echo "::error::Push failed with unexpected error"
+    echo "::error::Push failed with unexpected error (git push origin ${BRANCH})" >&2
+    echo "::error::Push output: ${PUSH_OUTPUT}" >&2
     exit 1
   fi
 fi
@@ -406,15 +407,19 @@ Closes #${ISSUE_NUMBER}
 - [x] Pre-commit hooks passed (authoritative run on runner)
 - [x] Tests ran inside sandbox"
 
+PR_CREATE_STDERR=$(mktemp)
 if ! PR_URL=$(gh pr create \
   --repo "${REPO_FULL_NAME}" \
   --head "${BRANCH}" \
   --base "${TARGET_BRANCH}" \
   --title "${PR_TITLE}" \
-  --body "${PR_BODY}"); then
-  echo "::error::Failed to create PR: see above for details"
+  --body "${PR_BODY}" 2>"${PR_CREATE_STDERR}"); then
+  echo "::error::Failed to create PR for ${REPO_FULL_NAME} (head: ${BRANCH}, base: ${TARGET_BRANCH})" >&2
+  [ -s "${PR_CREATE_STDERR}" ] && cat "${PR_CREATE_STDERR}" >&2
+  rm -f "${PR_CREATE_STDERR}"
   exit 1
 fi
+rm -f "${PR_CREATE_STDERR}"
 
 echo "PR created: ${PR_URL}"
 echo "pr_url=${PR_URL}" >> "${GITHUB_OUTPUT:-/dev/null}"
diff --git a/internal/scaffold/fullsend-repo/scripts/post-fix.sh b/internal/scaffold/fullsend-repo/scripts/post-fix.sh
index 5f2fe75714..84721af3af 100644
--- a/internal/scaffold/fullsend-repo/scripts/post-fix.sh
+++ b/internal/scaffold/fullsend-repo/scripts/post-fix.sh
@@ -73,7 +73,7 @@ RUN_DIR="$(pwd)"
 
 if [ "${REPO_DIR}" != "." ]; then
   if [ ! -d "${REPO_DIR}" ]; then
-    echo "::error::Extracted repo not found at ${REPO_DIR}"
+    echo "::error::Extracted repo not found at ${REPO_DIR}" >&2
     exit 1
   fi
   cd "${REPO_DIR}"
@@ -172,9 +172,9 @@ if [ "${NO_PUSH}" = "false" ]; then
   # -------------------------------------------------------------------------
   echo "Checking for Signed-off-by trailers in agent's commit(s)..."
   if git log --format='%b' "${SCAN_RANGE}" | grep -q '^Signed-off-by:'; then
-    echo "::error::BLOCKED — agent commit contains a Signed-off-by trailer"
-    echo "::error::Agents must not use 'git commit -s' or append Signed-off-by trailers."
-    echo "::error::DCO is a human attestation; the DCO app waives the check for bots."
+    echo "::error::BLOCKED — agent commit contains a Signed-off-by trailer" >&2
+    echo "::error::Agents must not use 'git commit -s' or append Signed-off-by trailers." >&2
+    echo "::error::DCO is a human attestation; the DCO app waives the check for bots." >&2
     exit 1
   fi
   echo "Signed-off-by scan passed — no trailers in agent's commit(s)"
@@ -189,7 +189,7 @@ if ! command -v lychee >/dev/null 2>&1; then
   case "$(uname -m)" in
     x86_64)  LY_TRIPLE="x86_64-unknown-linux-gnu";  LY_SHA="${LYCHEE_SHA256_AMD64}" ;;
     aarch64) LY_TRIPLE="aarch64-unknown-linux-gnu"; LY_SHA="${LYCHEE_SHA256_ARM64}" ;;
-    *) echo "::error::Unsupported architecture for lychee: $(uname -m)"; exit 1 ;;
+    *) echo "::error::Unsupported architecture for lychee: $(uname -m)" >&2; exit 1 ;;
   esac
   curl -fsSL \
     "https://github.com/lycheeverse/lychee/releases/download/lychee-v${LYCHEE_VERSION}/lychee-${LY_TRIPLE}.tar.gz" \
@@ -236,7 +236,7 @@ if [ "${NO_PUSH}" = "false" ] && [ -f .pre-commit-config.yaml ]; then
     if pre-commit run --files "${changed_array[@]}"; then
       echo "Pre-commit passed — all hooks clean"
     else
-      echo "::error::BLOCKED — pre-commit hooks failed on agent's changes"
+      echo "::error::BLOCKED — pre-commit hooks failed on agent's changes" >&2
       exit 1
     fi
   else
@@ -294,7 +294,7 @@ else
     SCAN_DIR="$(mktemp -d)"
     cp "${RESULT_FILE}" "${SCAN_DIR}/fix-result.json"
     if ! gitleaks detect --source "${SCAN_DIR}" --no-git --redact 2>/dev/null; then
-      echo "::error::Secret detected in fix-result.json — refusing to post PR comment"
+      echo "::error::Secret detected in fix-result.json — refusing to post PR comment" >&2
       rm -rf "${SCAN_DIR}"
       exit 1
     fi
@@ -305,7 +305,8 @@ else
   PROCESS_EXIT=0
   python3 "${PROCESS_SCRIPT}" "${RESULT_FILE}" "${REPO_FULL_NAME}" "${PR_NUMBER}" || PROCESS_EXIT=$?
   if [ "${PROCESS_EXIT}" -eq 1 ]; then
-    exit 1  # hard failure (bad input)
+    echo "::error::process-fix-result.py failed with exit code 1 (bad input) for PR #${PR_NUMBER} in ${REPO_FULL_NAME}" >&2
+    exit 1
   elif [ "${PROCESS_EXIT}" -ne 0 ]; then
     echo "::warning::process-fix-result.py exited ${PROCESS_EXIT} — continuing with labels/summary"
   fi
diff --git a/internal/scaffold/fullsend-repo/scripts/post-prioritize.sh b/internal/scaffold/fullsend-repo/scripts/post-prioritize.sh
index d51140573a..5c57b2914b 100755
--- a/internal/scaffold/fullsend-repo/scripts/post-prioritize.sh
+++ b/internal/scaffold/fullsend-repo/scripts/post-prioritize.sh
@@ -23,7 +23,7 @@ source "${SCRIPT_DIR}/lib/github-api-csma.sh"
 
 # Validate URL format early, before any parsing or API calls.
 if [[ ! "${GITHUB_ISSUE_URL}" =~ ^https://github\.com/[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+/issues/[0-9]+$ ]]; then
-  echo "ERROR: GITHUB_ISSUE_URL does not match expected pattern: ${GITHUB_ISSUE_URL}"
+  echo "ERROR: GITHUB_ISSUE_URL does not match expected pattern: ${GITHUB_ISSUE_URL}" >&2
   exit 1
 fi
 
@@ -36,14 +36,14 @@ for dir in iteration-*/output; do
 done
 
 if [[ -z "${RESULT_FILE}" ]]; then
-  echo "ERROR: agent-result.json not found in any iteration output directory"
+  echo "ERROR: agent-result.json not found in any iteration output directory" >&2
   exit 1
 fi
 
 echo "Reading RICE result from: ${RESULT_FILE}"
 
 if ! jq empty "${RESULT_FILE}" 2>/dev/null; then
-  echo "ERROR: ${RESULT_FILE} is not valid JSON"
+  echo "ERROR: ${RESULT_FILE} is not valid JSON" >&2
   exit 1
 fi
 
@@ -99,7 +99,7 @@ ITEM_ID=$(echo "${ITEM_RESPONSE}" | jq -r --arg pid "${PROJECT_ID}" \
   '(.data.node.projectItems.nodes // [])[] | select(.project.id == $pid) | .id')
 
 if [[ -z "${ITEM_ID}" || "${ITEM_ID}" == "null" ]]; then
-  echo "ERROR: issue ${GITHUB_ISSUE_URL} not found on project board"
+  echo "ERROR: issue ${GITHUB_ISSUE_URL} not found on project board (project: ${PROJECT_NUMBER}, org: ${ORG})" >&2
   exit 1
 fi
 
@@ -118,7 +118,7 @@ SCORE_FIELD_ID=$(get_field_id "RICE Score")
 
 for fid_var in REACH_FIELD_ID IMPACT_FIELD_ID CONFIDENCE_FIELD_ID EFFORT_FIELD_ID SCORE_FIELD_ID; do
   if [[ -z "${!fid_var}" ]]; then
-    echo "ERROR: ${fid_var} not found on project board. Run scripts/setup-prioritize.sh first."
+    echo "ERROR: ${fid_var} not found on project board (project: ${PROJECT_NUMBER}, org: ${ORG}). Run scripts/setup-prioritize.sh first." >&2
     exit 1
   fi
 done
diff --git a/internal/scaffold/fullsend-repo/scripts/post-retro.sh b/internal/scaffold/fullsend-repo/scripts/post-retro.sh
index 5badca93cf..28e284bed6 100755
--- a/internal/scaffold/fullsend-repo/scripts/post-retro.sh
+++ b/internal/scaffold/fullsend-repo/scripts/post-retro.sh
@@ -26,7 +26,7 @@ for dir in iteration-*/output; do
 done
 
 if [[ -z "${RESULT_FILE}" ]]; then
-  echo "ERROR: agent-result.json not found in any iteration output directory"
+  echo "ERROR: agent-result.json not found in any iteration output directory" >&2
   exit 1
 fi
 
@@ -34,14 +34,14 @@ echo "Reading retro result from: ${RESULT_FILE}"
 
 # Validate JSON is parseable.
 if ! jq empty "${RESULT_FILE}" 2>/dev/null; then
-  echo "ERROR: ${RESULT_FILE} is not valid JSON"
+  echo "ERROR: ${RESULT_FILE} is not valid JSON" >&2
   exit 1
 fi
 
 # Extract repo and number from ORIGINATING_URL.
 # Accepts both /issues/N and /pull/N.
 if [[ ! "${ORIGINATING_URL}" =~ ^https://github\.com/[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+/(issues|pull)/[0-9]+$ ]]; then
-  echo "ERROR: ORIGINATING_URL does not match expected pattern: ${ORIGINATING_URL}"
+  echo "ERROR: ORIGINATING_URL does not match expected pattern: ${ORIGINATING_URL}" >&2
   exit 1
 fi
 ORIGINATING_REPO=$(echo "${ORIGINATING_URL}" | sed -E 's#https://github.com/##; s#/(issues|pull)/.*##')
@@ -57,16 +57,16 @@ echo "Found ${PROPOSAL_COUNT} proposal(s)"
 for i in $(seq 0 $((PROPOSAL_COUNT - 1))); do
   TR=$(jq -r ".proposals[$i].target_repo" "${RESULT_FILE}")
   if [[ ! "${TR}" =~ ^[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+$ ]]; then
-    echo "ERROR: proposal[$i].target_repo is not a valid owner/repo: ${TR}"
+    echo "ERROR: proposal[$i].target_repo is not a valid owner/repo: ${TR}" >&2
     exit 1
   fi
   TI=$(jq -r ".proposals[$i].title // empty" "${RESULT_FILE}")
   if [[ -z "${TI}" ]]; then
-    echo "ERROR: proposal[$i].title is missing or empty"
+    echo "ERROR: proposal[$i].title is missing or empty" >&2
     exit 1
   fi
   jq -e ".proposals[$i] | .what_happened and .what_could_go_better and .proposed_change and .validation_criteria" "${RESULT_FILE}" >/dev/null 2>&1 || {
-    echo "ERROR: proposal[$i] is missing required fields"
+    echo "ERROR: proposal[$i] is missing required fields" >&2
     exit 1
   }
 done
@@ -98,7 +98,7 @@ for i in $(seq 0 $((PROPOSAL_COUNT - 1))); do
     --repo "${TARGET_REPO}" \
     --title "${TITLE}" \
     --body "${BODY}" 2>&1); then
-    echo "ERROR: failed to create issue in ${TARGET_REPO}: ${ISSUE_URL}"
+    echo "ERROR: failed to create issue in ${TARGET_REPO} (gh issue create --repo ${TARGET_REPO}): ${ISSUE_URL}" >&2
     exit 1
   fi
 
@@ -113,7 +113,7 @@ done
 # number is a PR. See https://github.com/orgs/community/discussions/26644
 SUMMARY=$(jq -r '.summary // empty' "${RESULT_FILE}")
 if [[ -z "${SUMMARY}" ]]; then
-  echo "ERROR: .summary is missing or empty in agent result"
+  echo "ERROR: .summary is missing or empty in agent result" >&2
   exit 1
 fi
 
diff --git a/internal/scaffold/fullsend-repo/scripts/post-review.sh b/internal/scaffold/fullsend-repo/scripts/post-review.sh
index ee196d4461..d2bdd10c7b 100755
--- a/internal/scaffold/fullsend-repo/scripts/post-review.sh
+++ b/internal/scaffold/fullsend-repo/scripts/post-review.sh
@@ -21,7 +21,7 @@ set -euo pipefail
 : "${REVIEW_TOKEN:?REVIEW_TOKEN is required}"
 : "${PR_NUMBER:?PR_NUMBER is required}"
 if ! [[ "${PR_NUMBER}" =~ ^[0-9]+$ ]]; then
-  echo "::error::PR_NUMBER must be a positive integer"
+  echo "::error::PR_NUMBER must be a positive integer" >&2
   exit 1
 fi
 : "${REPO_FULL_NAME:?REPO_FULL_NAME is required}"
@@ -97,7 +97,7 @@ DOWNGRADED=false
 if [ "${ACTION}" = "approve" ]; then
   PR_FILES=$(gh pr view "${PR_NUMBER}" --repo "${REPO_FULL_NAME}" --json files --jq '.files[].path')
   if [ -z "${PR_FILES}" ]; then
-    echo "::error::Failed to fetch PR files or PR has no changed files — refusing to approve"
+    echo "::error::Failed to fetch PR files or PR has no changed files — refusing to approve (gh pr view --json files)" >&2
     exit 1
   fi
 
@@ -177,6 +177,7 @@ ${REDISPATCH_MARKER}" || echo "::warning::Failed to post re-dispatch comment"
   # appear as a failure.
   exit 0
 elif [ "${POST_REVIEW_EXIT}" -ne 0 ]; then
+  echo "::error::fullsend post-review failed with exit code ${POST_REVIEW_EXIT} (PR #${PR_NUMBER} in ${REPO_FULL_NAME})" >&2
   exit "${POST_REVIEW_EXIT}"
 fi
 
diff --git a/internal/scaffold/fullsend-repo/scripts/post-triage.sh b/internal/scaffold/fullsend-repo/scripts/post-triage.sh
index 7077ddca13..fcfe7918b7 100755
--- a/internal/scaffold/fullsend-repo/scripts/post-triage.sh
+++ b/internal/scaffold/fullsend-repo/scripts/post-triage.sh
@@ -29,7 +29,7 @@ for dir in iteration-*/output; do
 done
 
 if [[ -z "${RESULT_FILE}" ]]; then
-  echo "ERROR: agent-result.json not found in any iteration output directory"
+  echo "ERROR: agent-result.json not found in any iteration output directory" >&2
   exit 1
 fi
 
@@ -37,7 +37,7 @@ echo "Reading triage result from: ${RESULT_FILE}"
 
 # Validate JSON is parseable.
 if ! jq empty "${RESULT_FILE}" 2>/dev/null; then
-  echo "ERROR: ${RESULT_FILE} is not valid JSON"
+  echo "ERROR: ${RESULT_FILE} is not valid JSON" >&2
   exit 1
 fi
 
@@ -47,7 +47,7 @@ COMMENT=$(jq -r '.comment // empty' "${RESULT_FILE}")
 # Validate and extract repo and issue number from the HTML URL.
 # GITHUB_ISSUE_URL is e.g. https://github.com/org/repo/issues/42
 if [[ ! "${GITHUB_ISSUE_URL}" =~ ^https://github\.com/[a-zA-Z0-9._-]+/[a-zA-Z0-9._-]+/issues/[0-9]+$ ]]; then
-  echo "ERROR: GITHUB_ISSUE_URL does not match expected pattern: ${GITHUB_ISSUE_URL}"
+  echo "ERROR: GITHUB_ISSUE_URL does not match expected pattern: ${GITHUB_ISSUE_URL}" >&2
   exit 1
 fi
 REPO=$(echo "${GITHUB_ISSUE_URL}" | sed 's|https://github.com/||; s|/issues/.*||')
@@ -59,8 +59,11 @@ echo "Issue: #${ISSUE_NUMBER}"
 
 # add_label uses the labels API to avoid firing issues.edited.
 add_label() {
-  if ! gh api "repos/${REPO}/issues/${ISSUE_NUMBER}/labels" -f "labels[]=$1" --silent; then
-    echo "ERROR: failed to add label '$1' to issue #${ISSUE_NUMBER}" >&2
+  local endpoint="repos/${REPO}/issues/${ISSUE_NUMBER}/labels"
+  local err_output
+  if ! err_output=$(gh api "${endpoint}" -f "labels[]=$1" --silent 2>&1); then
+    echo "ERROR: failed to add label '$1' to issue #${ISSUE_NUMBER} (POST ${endpoint})" >&2
+    [[ -n "${err_output}" ]] && echo "ERROR: ${err_output}" >&2
     exit 1
   fi
 }
@@ -98,7 +101,7 @@ DEFERRED_LABEL=""
 case "${ACTION}" in
   insufficient)
     if [[ -z "${COMMENT}" ]]; then
-      echo "ERROR: action is 'insufficient' but no comment provided"
+      echo "ERROR: action is 'insufficient' but no comment provided" >&2
       exit 1
     fi
     remove_label "blocked"
@@ -107,12 +110,12 @@ case "${ACTION}" in
 
   duplicate)
     if [[ -z "${COMMENT}" ]]; then
-      echo "ERROR: action is 'duplicate' but no comment provided"
+      echo "ERROR: action is 'duplicate' but no comment provided" >&2
       exit 1
     fi
     DUPLICATE_OF=$(jq -r '.duplicate_of' "${RESULT_FILE}")
     if [[ "${DUPLICATE_OF}" -eq "${ISSUE_NUMBER}" ]]; then
-      echo "ERROR: issue cannot be a duplicate of itself (#${ISSUE_NUMBER})"
+      echo "ERROR: issue cannot be a duplicate of itself (#${ISSUE_NUMBER})" >&2
       exit 1
     fi
     remove_label "blocked"
@@ -121,7 +124,7 @@ case "${ACTION}" in
 
   prerequisites)
     if [[ -z "${COMMENT}" ]]; then
-      echo "ERROR: action is 'prerequisites' but no comment provided"
+      echo "ERROR: action is 'prerequisites' but no comment provided" >&2
       exit 1
     fi
 
@@ -241,7 +244,7 @@ ${FAILED_CREATES}"
 
   sufficient)
     if [[ -z "${COMMENT}" ]]; then
-      echo "ERROR: action is 'sufficient' but no comment provided"
+      echo "ERROR: action is 'sufficient' but no comment provided" >&2
       exit 1
     fi
 
@@ -249,7 +252,7 @@ ${FAILED_CREATES}"
     # If the agent identified open questions, it should have used "insufficient".
     GAP_COUNT=$(jq '.triage_summary.information_gaps // [] | length' "${RESULT_FILE}")
     if [[ "${GAP_COUNT}" -gt 0 ]]; then
-      echo "ERROR: action is 'sufficient' but triage_summary contains ${GAP_COUNT} information_gaps — open questions must block triage"
+      echo "ERROR: action is 'sufficient' but triage_summary contains ${GAP_COUNT} information_gaps — open questions must block triage" >&2
       exit 1
     fi
 
@@ -281,7 +284,7 @@ ${FAILED_CREATES}"
 
   question)
     if [[ -z "${COMMENT}" ]]; then
-      echo "ERROR: action is 'question' but no comment provided"
+      echo "ERROR: action is 'question' but no comment provided" >&2
       exit 1
     fi
     remove_label "blocked"
@@ -290,7 +293,7 @@ ${FAILED_CREATES}"
     ;;
 
   *)
-    echo "ERROR: unknown action '${ACTION}' — this may be a newer action that post-triage.sh does not handle yet"
+    echo "ERROR: unknown action '${ACTION}' — this may be a newer action that post-triage.sh does not handle yet" >&2
     exit 1
     ;;
 esac