From 80a5c4d57acdd3413865c1a99876e9c709660ad1 Mon Sep 17 00:00:00 2001
From: marcie <marcie@fleet.mosaicstack.dev>
Date: Sat, 29 Aug 2026 01:59:41 +0000
Subject: [PATCH] framework tools/git: R1/R4 usage-error contract across 16
 wrappers (P1, census-corrected per review 358) (#1464)

Co-authored-by: marcie <marcie@fleet.mosaicstack.dev>
---
 .../framework/tools/git/issue-assign.sh       |  43 ++++-
 .../mosaic/framework/tools/git/issue-close.sh |  51 ++++--
 .../framework/tools/git/issue-comment.sh      |   6 +-
 .../framework/tools/git/issue-create.sh       |  19 ++-
 .../mosaic/framework/tools/git/issue-edit.sh  |  30 +++-
 .../mosaic/framework/tools/git/issue-list.sh  |  23 ++-
 .../framework/tools/git/issue-reopen.sh       |  55 +++++--
 .../mosaic/framework/tools/git/issue-view.sh  |  19 ++-
 .../mosaic/framework/tools/git/lane-brief.sh  |  29 ++--
 .../framework/tools/git/milestone-close.sh    |  23 ++-
 .../framework/tools/git/milestone-create.sh   |  32 +++-
 .../framework/tools/git/milestone-list.sh     |  20 ++-
 .../mosaic/framework/tools/git/pr-close.sh    |  55 +++++--
 .../mosaic/framework/tools/git/pr-create.sh   |  20 ++-
 .../mosaic/framework/tools/git/pr-edit.sh     |  49 ++++--
 .../mosaic/framework/tools/git/pr-review.sh   |  74 ++++++---
 .../git/test-issue-assign-usage-contract.sh   | 154 ++++++++++++++++++
 .../git/test-issue-close-usage-contract.sh    | 136 ++++++++++++++++
 .../git/test-issue-comment-usage-contract.sh  |   9 +-
 .../git/test-issue-create-usage-contract.sh   | 132 +++++++++++++++
 .../git/test-issue-edit-usage-contract.sh     | 132 +++++++++++++++
 .../git/test-issue-list-usage-contract.sh     | 130 +++++++++++++++
 .../git/test-issue-reopen-usage-contract.sh   | 136 ++++++++++++++++
 .../git/test-issue-view-usage-contract.sh     | 132 +++++++++++++++
 .../tools/git/test-lane-brief-pr-linkage.sh   |   0
 .../git/test-lane-brief-usage-contract.sh     | 132 +++++++++++++++
 .../test-milestone-close-usage-contract.sh    | 132 +++++++++++++++
 .../test-milestone-create-usage-contract.sh   | 132 +++++++++++++++
 .../git/test-milestone-list-usage-contract.sh | 153 +++++++++++++++++
 .../tools/git/test-pr-close-usage-contract.sh | 133 +++++++++++++++
 .../git/test-pr-create-usage-contract.sh      | 132 +++++++++++++++
 .../tools/git/test-pr-edit-usage-contract.sh  | 140 ++++++++++++++++
 .../tools/git/test-pr-review-gitea-comment.sh |   0
 .../git/test-pr-review-repo-host-override.sh  |   2 +-
 .../git/test-pr-review-usage-contract.sh      | 148 +++++++++++++++++
 packages/mosaic/package.json                  |   2 +-
 36 files changed, 2483 insertions(+), 132 deletions(-)
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-assign-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-close-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-create-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-edit-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-list-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-reopen-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-issue-view-usage-contract.sh
 mode change 100644 => 100755 packages/mosaic/framework/tools/git/test-lane-brief-pr-linkage.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-lane-brief-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-milestone-close-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-milestone-create-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-milestone-list-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-pr-close-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-pr-create-usage-contract.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-pr-edit-usage-contract.sh
 mode change 100644 => 100755 packages/mosaic/framework/tools/git/test-pr-review-gitea-comment.sh
 create mode 100755 packages/mosaic/framework/tools/git/test-pr-review-usage-contract.sh

diff --git a/packages/mosaic/framework/tools/git/issue-assign.sh b/packages/mosaic/framework/tools/git/issue-assign.sh
index 48d5c04b..1dad6987 100755
--- a/packages/mosaic/framework/tools/git/issue-assign.sh
+++ b/packages/mosaic/framework/tools/git/issue-assign.sh
@@ -3,6 +3,7 @@
 # Usage: issue-assign.sh -i ISSUE_NUMBER [-a assignee] [-l labels] [-m milestone]
 
 set -e
+set -o pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"
@@ -33,25 +34,36 @@ Examples:
     $(basename "$0") -i 42 -l "in-progress" -m "0.2.0"
     $(basename "$0") -i 42 -a @me
 EOF
-    exit "${1:-1}"
+    exit "${1:-2}"
+}
+
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    usage >&2
 }
 
 # Parse arguments
 while [[ $# -gt 0 ]]; do
     case $1 in
         -i|--issue)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE="$2"
             shift 2
             ;;
         -a|--assignee)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ASSIGNEE="$2"
             shift 2
             ;;
         -l|--labels)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LABELS="$2"
             shift 2
             ;;
         -m|--milestone)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             MILESTONE="$2"
             shift 2
             ;;
@@ -79,20 +91,35 @@ PLATFORM=$(detect_platform)
 case "$PLATFORM" in
     github)
         if [[ -n "$ASSIGNEE" ]]; then
-            gh issue edit "$ISSUE" --add-assignee "$ASSIGNEE"
+            prov_rc=0
+            gh issue edit "$ISSUE" --add-assignee "$ASSIGNEE" || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         fi
         if [[ "$REMOVE_ASSIGNEE" == true ]]; then
             # Get current assignees and remove them
-            CURRENT=$(gh issue view "$ISSUE" --json assignees -q '.assignees[].login' 2>/dev/null | tr '\n' ',')
+            # pipefail preserves the provider status through the pipeline;
+            # a FAILED lookup exits here instead of reading as a silent
+            # no-assignees skip (codex PR #1464). A successful lookup with
+            # zero assignees still skips the edit below.
+            CURRENT=$(gh issue view "$ISSUE" --json assignees -q '.assignees[].login' 2>/dev/null | tr '\n' ',') || {
+                echo "Error: could not read current assignees (provider lookup failed)" >&2
+                exit 1
+            }
             if [[ -n "$CURRENT" ]]; then
-                gh issue edit "$ISSUE" --remove-assignee "${CURRENT%,}"
+                prov_rc=0
+                gh issue edit "$ISSUE" --remove-assignee "${CURRENT%,}" || prov_rc=$?
+                [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
             fi
         fi
         if [[ -n "$LABELS" ]]; then
-            gh issue edit "$ISSUE" --add-label "$LABELS"
+            prov_rc=0
+            gh issue edit "$ISSUE" --add-label "$LABELS" || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         fi
         if [[ -n "$MILESTONE" ]]; then
-            gh issue edit "$ISSUE" --milestone "$MILESTONE"
+            prov_rc=0
+            gh issue edit "$ISSUE" --milestone "$MILESTONE" || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         fi
         echo "Issue #$ISSUE updated successfully"
         ;;
@@ -131,7 +158,9 @@ case "$PLATFORM" in
         fi
 
         if [[ "$NEEDS_EDIT" == true ]]; then
-            "${CMD[@]}"
+            prov_rc=0
+            "${CMD[@]}" || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
             echo "Issue #$ISSUE updated successfully"
         else
             echo "No changes specified"
diff --git a/packages/mosaic/framework/tools/git/issue-close.sh b/packages/mosaic/framework/tools/git/issue-close.sh
index 3d014a59..78d92384 100755
--- a/packages/mosaic/framework/tools/git/issue-close.sh
+++ b/packages/mosaic/framework/tools/git/issue-close.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 # issue-close.sh - Close an issue on GitHub or Gitea
-# Usage: issue-close.sh -i <issue_number> [-c <comment>]
+# Usage: issue-close.sh -i <issue_number> [-b <comment>]
+# (-c/--comment is a backward-compatible alias for -b/--body; R1/R4 2026-08-28)
 
 set -e
 
@@ -12,35 +13,49 @@ source "$SCRIPT_DIR/detect-platform.sh"
 ISSUE_NUMBER=""
 COMMENT=""
 
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1), so a
+# caller or stop gate can tell an invocation defect from a delivery blocker.
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: issue-close.sh -i <issue_number> [-b <comment>] (see --help)" >&2
+    exit 2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -i|--issue)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE_NUMBER="$2"
             shift 2
             ;;
-        -c|--comment)
+        -b|--body|-c|--comment)
+            # R1 (2026-08-28): --body is the canonical flag; -c/--comment stays
+            # a backward-compatible alias.
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             COMMENT="$2"
             shift 2
             ;;
         -h|--help)
-            echo "Usage: issue-close.sh -i <issue_number> [-c <comment>]"
+            echo "Usage: issue-close.sh -i <issue_number> [-b <comment>]"
             echo ""
             echo "Options:"
             echo "  -i, --issue    Issue number (required)"
-            echo "  -c, --comment  Comment to add before closing (optional)"
+            echo "  -b, --body     Comment to add before closing (optional; canonical)"
+            echo "  -c, --comment  Alias for --body"
             echo "  -h, --help     Show this help"
+            echo ""
+            echo "Exit codes: 0 success; 2 usage error (stderr); 1 provider/credential/verification failure."
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$ISSUE_NUMBER" ]]; then
-    echo "Error: Issue number is required (-i)"
-    exit 1
+    usage_error "issue number is required (-i/--issue)"
 fi
 
 # Detect platform and close issue
@@ -82,10 +97,22 @@ gitea_issue_close_api() {
 }
 
 if [[ "$PLATFORM" == "github" ]]; then
+    # R4: normalize provider failures to exit 1 (gh's own usage errors exit 2
+    # and would collide with the reserved usage-error status).
     if [[ -n "$COMMENT" ]]; then
-        gh issue comment "$ISSUE_NUMBER" --body "$COMMENT"
+        gh_rc=0
+        gh issue comment "$ISSUE_NUMBER" --body "$COMMENT" || gh_rc=$?
+        if [[ "$gh_rc" -ne 0 ]]; then
+            echo "Error: GitHub comment before close failed (gh exit $gh_rc)" >&2
+            exit 1
+        fi
+    fi
+    gh_rc=0
+    gh issue close "$ISSUE_NUMBER" || gh_rc=$?
+    if [[ "$gh_rc" -ne 0 ]]; then
+        echo "Error: GitHub issue close failed (gh exit $gh_rc)" >&2
+        exit 1
     fi
-    gh issue close "$ISSUE_NUMBER"
     echo "Closed GitHub issue #$ISSUE_NUMBER"
 elif [[ "$PLATFORM" == "gitea" ]]; then
     GITEA_LOGIN_NAME=$(get_gitea_login || true)
@@ -107,7 +134,9 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
                 exit 1
             }
         fi
-        tea issue close "$ISSUE_NUMBER" --repo "$OWNER/$REPO" --login "$GITEA_LOGIN_NAME"
+        prov_rc=0
+        tea issue close "$ISSUE_NUMBER" --repo "$OWNER/$REPO" --login "$GITEA_LOGIN_NAME" || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     else
         echo "No tea login configured for $(get_remote_host); using authenticated Gitea API fallback." >&2
         if [[ -n "$COMMENT" ]]; then
diff --git a/packages/mosaic/framework/tools/git/issue-comment.sh b/packages/mosaic/framework/tools/git/issue-comment.sh
index e5858b35..d5b74028 100755
--- a/packages/mosaic/framework/tools/git/issue-comment.sh
+++ b/packages/mosaic/framework/tools/git/issue-comment.sh
@@ -46,7 +46,7 @@ usage_error() {
 while [[ $# -gt 0 ]]; do
     case $1 in
         -i|--issue)
-            [[ $# -ge 2 ]] || usage_error "option $1 requires a value"
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE_NUMBER="$2"
             shift 2
             ;;
@@ -54,12 +54,12 @@ while [[ $# -gt 0 ]]; do
             # R1 (2026-08-28): --body is the canonical flag, matching
             # issue-create/issue-edit/pr-create/pr-edit; -c/--comment stays a
             # backward-compatible alias.
-            [[ $# -ge 2 ]] || usage_error "option $1 requires a value"
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             COMMENT="$2"
             shift 2
             ;;
         -l|--login)
-            [[ $# -ge 2 ]] || usage_error "option $1 requires a value"
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LOGIN_OVERRIDE="$2"
             shift 2
             ;;
diff --git a/packages/mosaic/framework/tools/git/issue-create.sh b/packages/mosaic/framework/tools/git/issue-create.sh
index d9c0bc24..e0b061a6 100755
--- a/packages/mosaic/framework/tools/git/issue-create.sh
+++ b/packages/mosaic/framework/tools/git/issue-create.sh
@@ -74,26 +74,39 @@ Examples:
     $(basename "$0") -t "Fix login bug" -l "bug,priority-high"
     $(basename "$0") -t "Add dark mode" -b "Implement theme switching" -m "0.2.0"
     $(basename "$0") -i
+
+Exit codes: 0 success; 2 usage error (stderr); 1 provider/credential failure.
 EOF
-    exit "${1:-1}"
+    exit "${1:-2}"
 }
 
 # Parse arguments
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    usage >&2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -t|--title)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             TITLE="$2"
             shift 2
             ;;
         -b|--body)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             BODY="$2"
             shift 2
             ;;
         -l|--labels)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LABELS="$2"
             shift 2
             ;;
         -m|--milestone)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             MILESTONE="$2"
             shift 2
             ;;
@@ -131,7 +144,9 @@ case "$PLATFORM" in
         [[ -n "$BODY" ]] && CMD+=(--body "$BODY")
         [[ -n "$LABELS" ]] && CMD+=(--label "$LABELS")
         [[ -n "$MILESTONE" ]] && CMD+=(--milestone "$MILESTONE")
-        "${CMD[@]}"
+        prov_rc=0
+        "${CMD[@]}" || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         ;;
     gitea)
         if command -v tea >/dev/null 2>&1; then
diff --git a/packages/mosaic/framework/tools/git/issue-edit.sh b/packages/mosaic/framework/tools/git/issue-edit.sh
index 865af4fc..20465de9 100755
--- a/packages/mosaic/framework/tools/git/issue-edit.sh
+++ b/packages/mosaic/framework/tools/git/issue-edit.sh
@@ -14,25 +14,39 @@ BODY=""
 LABELS=""
 MILESTONE=""
 
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1), so a
+# caller or stop gate can tell an invocation defect from a delivery blocker.
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: issue-edit.sh -i <issue_number> [-t <title>] [-b <body>] [-l <labels>] [-m <milestone>] (see --help)" >&2
+    exit 2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -i|--issue)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE_NUMBER="$2"
             shift 2
             ;;
         -t|--title)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             TITLE="$2"
             shift 2
             ;;
         -b|--body)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             BODY="$2"
             shift 2
             ;;
         -l|--labels)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LABELS="$2"
             shift 2
             ;;
         -m|--milestone)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             MILESTONE="$2"
             shift 2
             ;;
@@ -46,18 +60,18 @@ while [[ $# -gt 0 ]]; do
             echo "  -l, --labels     Labels (comma-separated, replaces existing)"
             echo "  -m, --milestone  Milestone name"
             echo "  -h, --help       Show this help"
+            echo ""
+            echo "Exit codes: 0 success; 2 usage error (stderr); 1 provider/credential/verification failure."
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$ISSUE_NUMBER" ]]; then
-    echo "Error: Issue number is required (-i)"
-    exit 1
+    usage_error "issue number is required (-i/--issue)"
 fi
 
 detect_platform >/dev/null
@@ -68,7 +82,9 @@ if [[ "$PLATFORM" == "github" ]]; then
     [[ -n "$BODY" ]] && CMD+=(--body "$BODY")
     [[ -n "$LABELS" ]] && CMD+=(--add-label "$LABELS")
     [[ -n "$MILESTONE" ]] && CMD+=(--milestone "$MILESTONE")
-    "${CMD[@]}"
+    prov_rc=0
+    "${CMD[@]}" || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     echo "Updated GitHub issue #$ISSUE_NUMBER"
 elif [[ "$PLATFORM" == "gitea" ]]; then
     REPO_SLUG=$(get_repo_slug) || {
@@ -84,7 +100,9 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
     [[ -n "$BODY" ]] && CMD+=(--description "$BODY")
     [[ -n "$LABELS" ]] && CMD+=(--add-labels "$LABELS")
     [[ -n "$MILESTONE" ]] && CMD+=(--milestone "$MILESTONE")
-    "${CMD[@]}"
+    prov_rc=0
+    "${CMD[@]}" || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     echo "Updated Gitea issue #$ISSUE_NUMBER"
 else
     echo "Error: Unknown platform"
diff --git a/packages/mosaic/framework/tools/git/issue-list.sh b/packages/mosaic/framework/tools/git/issue-list.sh
index 4e59d3d9..54ca1ce8 100755
--- a/packages/mosaic/framework/tools/git/issue-list.sh
+++ b/packages/mosaic/framework/tools/git/issue-list.sh
@@ -36,33 +36,46 @@ Examples:
     $(basename "$0") -m "0.2.0"               # Issues in milestone 0.2.0
     $(basename "$0") --repo ddk/ai-bma         # List issues from anywhere
 EOF
-    exit "${1:-1}"
+    exit "${1:-2}"
 }
 
 # Parse arguments
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    usage >&2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -s|--state)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             STATE="$2"
             shift 2
             ;;
         -l|--label)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LABEL="$2"
             shift 2
             ;;
         -m|--milestone)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             MILESTONE="$2"
             shift 2
             ;;
         -a|--assignee)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ASSIGNEE="$2"
             shift 2
             ;;
         -n|--limit)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LIMIT="$2"
             shift 2
             ;;
         -r|--repo)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             REPO_OVERRIDE="$2"
             shift 2
             ;;
@@ -95,7 +108,9 @@ case "$PLATFORM" in
         [[ -n "$LABEL" ]] && CMD+=(--label "$LABEL")
         [[ -n "$MILESTONE" ]] && CMD+=(--milestone "$MILESTONE")
         [[ -n "$ASSIGNEE" ]] && CMD+=(--assignee "$ASSIGNEE")
-        "${CMD[@]}"
+        prov_rc=0
+        "${CMD[@]}" || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         ;;
     gitea)
         if [[ -n "$REPO_OVERRIDE" ]]; then
@@ -114,7 +129,9 @@ case "$PLATFORM" in
         [[ -n "$MILESTONE" ]] && CMD+=(--milestones "$MILESTONE")
         # Note: tea may not support assignee filter directly in all versions.
         [[ -n "$ASSIGNEE" ]] && echo "Note: Assignee filtering may require manual review for Gitea" >&2
-        "${CMD[@]}"
+        prov_rc=0
+        "${CMD[@]}" || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         ;;
     *)
         echo "Error: Could not detect git platform" >&2
diff --git a/packages/mosaic/framework/tools/git/issue-reopen.sh b/packages/mosaic/framework/tools/git/issue-reopen.sh
index cb92acdc..d1011035 100755
--- a/packages/mosaic/framework/tools/git/issue-reopen.sh
+++ b/packages/mosaic/framework/tools/git/issue-reopen.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 # issue-reopen.sh - Reopen a closed issue on GitHub or Gitea
-# Usage: issue-reopen.sh -i <issue_number> [-c <comment>]
+# Usage: issue-reopen.sh -i <issue_number> [-b <comment>]
+# (-c/--comment is a backward-compatible alias for -b/--body; R1/R4 2026-08-28)
 
 set -e
 
@@ -11,35 +12,49 @@ source "$SCRIPT_DIR/detect-platform.sh"
 ISSUE_NUMBER=""
 COMMENT=""
 
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1), so a
+# caller or stop gate can tell an invocation defect from a delivery blocker.
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: issue-reopen.sh -i <issue_number> [-b <comment>] (see --help)" >&2
+    exit 2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -i|--issue)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE_NUMBER="$2"
             shift 2
             ;;
-        -c|--comment)
+        -b|--body|-c|--comment)
+            # R1 (2026-08-28): --body is the canonical flag; -c/--comment stays
+            # a backward-compatible alias.
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             COMMENT="$2"
             shift 2
             ;;
         -h|--help)
-            echo "Usage: issue-reopen.sh -i <issue_number> [-c <comment>]"
+            echo "Usage: issue-reopen.sh -i <issue_number> [-b <comment>]"
             echo ""
             echo "Options:"
             echo "  -i, --issue    Issue number (required)"
-            echo "  -c, --comment  Comment to add when reopening (optional)"
+            echo "  -b, --body     Comment to add when reopening (optional; canonical)"
+            echo "  -c, --comment  Alias for --body"
             echo "  -h, --help     Show this help"
+            echo ""
+            echo "Exit codes: 0 success; 2 usage error (stderr); 1 provider/credential/verification failure."
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$ISSUE_NUMBER" ]]; then
-    echo "Error: Issue number is required (-i)"
-    exit 1
+    usage_error "issue number is required (-i/--issue)"
 fi
 
 detect_platform >/dev/null
@@ -80,18 +95,34 @@ gitea_issue_reopen_api() {
 }
 
 if [[ "$PLATFORM" == "github" ]]; then
+    # R4: normalize provider failures to exit 1 (gh's own usage errors exit 2
+    # and would collide with the reserved usage-error status).
     if [[ -n "$COMMENT" ]]; then
-        gh issue comment "$ISSUE_NUMBER" --body "$COMMENT"
+        gh_rc=0
+        gh issue comment "$ISSUE_NUMBER" --body "$COMMENT" || gh_rc=$?
+        if [[ "$gh_rc" -ne 0 ]]; then
+            echo "Error: GitHub comment before reopen failed (gh exit $gh_rc)" >&2
+            exit 1
+        fi
+    fi
+    gh_rc=0
+    gh issue reopen "$ISSUE_NUMBER" || gh_rc=$?
+    if [[ "$gh_rc" -ne 0 ]]; then
+        echo "Error: GitHub issue reopen failed (gh exit $gh_rc)" >&2
+        exit 1
     fi
-    gh issue reopen "$ISSUE_NUMBER"
     echo "Reopened GitHub issue #$ISSUE_NUMBER"
 elif [[ "$PLATFORM" == "gitea" ]]; then
     REPO_ARGS=$(get_gitea_repo_args || true)
     if [[ -n "$REPO_ARGS" ]]; then
         if [[ -n "$COMMENT" ]]; then
-            tea issue comment "$ISSUE_NUMBER" "$COMMENT" $REPO_ARGS
+            prov_rc=0
+            tea issue comment "$ISSUE_NUMBER" "$COMMENT" $REPO_ARGS || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         fi
-        tea issue reopen "$ISSUE_NUMBER" $REPO_ARGS
+        prov_rc=0
+        tea issue reopen "$ISSUE_NUMBER" $REPO_ARGS || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     else
         echo "No tea login configured for $(get_remote_host); using authenticated Gitea API fallback." >&2
         if [[ -n "$COMMENT" ]]; then
diff --git a/packages/mosaic/framework/tools/git/issue-view.sh b/packages/mosaic/framework/tools/git/issue-view.sh
index da15bc10..dd0364f5 100755
--- a/packages/mosaic/framework/tools/git/issue-view.sh
+++ b/packages/mosaic/framework/tools/git/issue-view.sh
@@ -8,6 +8,14 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"
 
 # Parse arguments
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: issue-view.sh -i <issue_number> (see --help)" >&2
+    exit 2
+}
+
 ISSUE_NUMBER=""
 
 # get_remote_host and get_gitea_token are provided by detect-platform.sh
@@ -74,6 +82,7 @@ if comments:
 while [[ $# -gt 0 ]]; do
     case $1 in
         -i|--issue)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE_NUMBER="$2"
             shift 2
             ;;
@@ -88,21 +97,21 @@ while [[ $# -gt 0 ]]; do
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$ISSUE_NUMBER" ]]; then
-    echo "Error: Issue number is required (-i)"
-    exit 1
+    usage_error "Issue number is required"
 fi
 
 detect_platform >/dev/null
 
 if [[ "$PLATFORM" == "github" ]]; then
-    gh issue view "$ISSUE_NUMBER"
+    prov_rc=0
+    gh issue view "$ISSUE_NUMBER" || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
 elif [[ "$PLATFORM" == "gitea" ]]; then
     if command -v tea >/dev/null 2>&1; then
         # --comments is what makes tea print the comment bodies (#1357 F3).
diff --git a/packages/mosaic/framework/tools/git/lane-brief.sh b/packages/mosaic/framework/tools/git/lane-brief.sh
index 5a83fbe9..c8a07180 100755
--- a/packages/mosaic/framework/tools/git/lane-brief.sh
+++ b/packages/mosaic/framework/tools/git/lane-brief.sh
@@ -28,18 +28,25 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"
 
 REPO="" MILESTONE="" LABEL="" LOGIN="" LIMIT=100
-while getopts "r:m:l:L:n:h" opt; do
-  case "$opt" in
-    r) REPO="$OPTARG" ;;
-    m) MILESTONE="$OPTARG" ;;
-    l) LABEL="$OPTARG" ;;
-    L) LOGIN="$OPTARG" ;;
-    n) LIMIT="$OPTARG" ;;
-    h) grep '^#' "$0" | sed 's/^# \?//'; exit 0 ;;
-    *) echo "see -h" >&2; exit 2 ;;
+# R2 (2026-08-28): long-flag aliases with the same usage-error contract the
+# wrapper family shares (rc 2, stderr). getopts could not take long flags.
+usage_error() {
+  echo "Error: $*" >&2
+  echo "Usage: lane-brief.sh -r <owner/repo> [-m milestone] [-l label] [-L login] [-n limit]" >&2
+  exit 2
+}
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    -r|--repo) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; REPO="$2"; shift 2 ;;
+    -m|--milestone) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; MILESTONE="$2"; shift 2 ;;
+    -l|--label|--labels) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; LABEL="$2"; shift 2 ;;
+    -L|--login) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; LOGIN="$2"; shift 2 ;;
+    -n|--limit) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; LIMIT="$2"; shift 2 ;;
+    -h|--help) grep '^#' "$0" | sed 's/^# \?//'; exit 0 ;;
+    *) usage_error "unknown option: $1" ;;
   esac
 done
-[[ -n "$REPO" ]] || { echo "FATAL: -r <owner/repo> required" >&2; exit 2; }
+[[ -n "$REPO" ]] || usage_error "-r/--repo <owner/repo> required"
 
 # Resolve login: explicit -L, then $GITEA_LOGIN, then owner inference, then the
 # shared default-login resolver. Owner inference comes before the shared fallback
@@ -72,7 +79,7 @@ if [[ -z "$LOGIN" ]]; then
     fi
   fi
 fi
-[[ -n "$LOGIN" ]] || { echo "FATAL: could not resolve a Gitea login for $REPO (pass -L or set GITEA_LOGIN)" >&2; exit 2; }
+[[ -n "$LOGIN" ]] || { echo "FATAL: could not resolve a Gitea login for $REPO (pass -L or set GITEA_LOGIN)" >&2; exit 1; }
 
 command -v tea >/dev/null || { echo "FATAL: tea not found" >&2; exit 1; }
 command -v jq  >/dev/null || { echo "FATAL: jq not found" >&2; exit 1; }
diff --git a/packages/mosaic/framework/tools/git/milestone-close.sh b/packages/mosaic/framework/tools/git/milestone-close.sh
index f57e6cc3..9f31b542 100755
--- a/packages/mosaic/framework/tools/git/milestone-close.sh
+++ b/packages/mosaic/framework/tools/git/milestone-close.sh
@@ -8,11 +8,20 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"
 
 # Parse arguments
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: milestone-close.sh -t <title> (see --help)" >&2
+    exit 2
+}
+
 TITLE=""
 
 while [[ $# -gt 0 ]]; do
     case $1 in
         -t|--title)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             TITLE="$2"
             shift 2
             ;;
@@ -25,28 +34,30 @@ while [[ $# -gt 0 ]]; do
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$TITLE" ]]; then
-    echo "Error: Milestone title is required (-t)"
-    exit 1
+    usage_error "Milestone title is required"
 fi
 
 detect_platform >/dev/null
 
 if [[ "$PLATFORM" == "github" ]]; then
-    gh api -X PATCH "/repos/{owner}/{repo}/milestones/$(gh api "/repos/{owner}/{repo}/milestones" --jq ".[] | select(.title==\"$TITLE\") | .number")" -f state=closed
+    prov_rc=0
+    gh api -X PATCH "/repos/{owner}/{repo}/milestones/$(gh api "/repos/{owner}/{repo}/milestones" --jq ".[] | select(.title==\"$TITLE\") | .number")" -f state=closed || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     echo "Closed GitHub milestone: $TITLE"
 elif [[ "$PLATFORM" == "gitea" ]]; then
     REPO_ARGS=$(get_gitea_repo_args) || {
         echo "Error: Could not resolve Gitea repo/login for remote host" >&2
         exit 1
     }
-    tea milestone close "$TITLE" $REPO_ARGS
+    prov_rc=0
+    tea milestone close "$TITLE" $REPO_ARGS || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     echo "Closed Gitea milestone: $TITLE"
 else
     echo "Error: Unknown platform"
diff --git a/packages/mosaic/framework/tools/git/milestone-create.sh b/packages/mosaic/framework/tools/git/milestone-create.sh
index 72d8f299..c21acfce 100755
--- a/packages/mosaic/framework/tools/git/milestone-create.sh
+++ b/packages/mosaic/framework/tools/git/milestone-create.sh
@@ -3,6 +3,7 @@
 # Usage: milestone-create.sh -t "Title" [-d "Description"] [--due "YYYY-MM-DD"]
 
 set -e
+set -o pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"
@@ -37,21 +38,31 @@ Examples:
     $(basename "$0") -t "0.0.1" -d "Pre-MVP Foundation Sprint"
     $(basename "$0") -t "0.1.0" -d "MVP Release" --due "2025-03-01"
 EOF
-    exit "${1:-1}"
+    exit "${1:-2}"
 }
 
 # Parse arguments
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    usage >&2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -t|--title)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             TITLE="$2"
             shift 2
             ;;
         -d|--desc)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             DESCRIPTION="$2"
             shift 2
             ;;
         --due)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             DUE_DATE="$2"
             shift 2
             ;;
@@ -74,14 +85,18 @@ PLATFORM=$(detect_platform)
 if [[ "$LIST_ONLY" == true ]]; then
     case "$PLATFORM" in
         github)
-            gh api repos/:owner/:repo/milestones --jq '.[] | "\(.number)\t\(.title)\t\(.state)\t\(.open_issues)/\(.closed_issues) issues"'
+            prov_rc=0
+            gh api repos/:owner/:repo/milestones --jq '.[] | "\(.number)\t\(.title)\t\(.state)\t\(.open_issues)/\(.closed_issues) issues"' || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
             ;;
         gitea)
             REPO_ARGS=$(get_gitea_repo_args) || {
                 echo "Error: Could not resolve Gitea repo/login for remote host" >&2
                 exit 1
             }
-            tea milestones list $REPO_ARGS
+            prov_rc=0
+            tea milestones list $REPO_ARGS || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
             ;;
         *)
             echo "Error: Could not detect git platform" >&2
@@ -92,8 +107,7 @@ if [[ "$LIST_ONLY" == true ]]; then
 fi
 
 if [[ -z "$TITLE" ]]; then
-    echo "Error: Title is required (-t) for creating milestones" >&2
-    usage
+    usage_error "Title is required (-t) for creating milestones"
 fi
 
 case "$PLATFORM" in
@@ -109,7 +123,9 @@ case "$PLATFORM" in
              + (if $d != "" then {"description": $d} else {} end)
              + (if $due != "" then {"due_on": ($due + "T00:00:00Z")} else {} end)')
 
-        gh api repos/:owner/:repo/milestones --method POST --input - <<< "$JSON_PAYLOAD"
+        prov_rc=0
+        gh api repos/:owner/:repo/milestones --method POST --input - <<< "$JSON_PAYLOAD" || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         echo "Milestone '$TITLE' created successfully"
         ;;
     gitea)
@@ -120,7 +136,9 @@ case "$PLATFORM" in
         CMD=(tea milestones create --title "$TITLE")
         [[ -n "$DESCRIPTION" ]] && CMD+=(--description "$DESCRIPTION")
         [[ -n "$DUE_DATE" ]] && CMD+=(--deadline "$DUE_DATE")
-        "${CMD[@]}" $REPO_ARGS
+        prov_rc=0
+        "${CMD[@]}" $REPO_ARGS || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         echo "Milestone '$TITLE' created successfully"
         ;;
     *)
diff --git a/packages/mosaic/framework/tools/git/milestone-list.sh b/packages/mosaic/framework/tools/git/milestone-list.sh
index 3b46c3d5..2704cc9d 100755
--- a/packages/mosaic/framework/tools/git/milestone-list.sh
+++ b/packages/mosaic/framework/tools/git/milestone-list.sh
@@ -8,11 +8,20 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 source "$SCRIPT_DIR/detect-platform.sh"
 
 # Parse arguments
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: milestone-list.sh [-s <state>] (see --help)" >&2
+    exit 2
+}
+
 STATE="open"
 
 while [[ $# -gt 0 ]]; do
     case $1 in
         -s|--state)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             STATE="$2"
             shift 2
             ;;
@@ -25,8 +34,7 @@ while [[ $# -gt 0 ]]; do
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
@@ -34,13 +42,17 @@ done
 detect_platform >/dev/null
 
 if [[ "$PLATFORM" == "github" ]]; then
-    gh api "/repos/{owner}/{repo}/milestones?state=$STATE" --jq '.[] | "\(.title) (\(.state)) - \(.open_issues) open, \(.closed_issues) closed"'
+    prov_rc=0
+    gh api "/repos/{owner}/{repo}/milestones?state=$STATE" --jq '.[] | "\(.title) (\(.state)) - \(.open_issues) open, \(.closed_issues) closed"' || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
 elif [[ "$PLATFORM" == "gitea" ]]; then
     REPO_ARGS=$(get_gitea_repo_args) || {
         echo "Error: Could not resolve Gitea repo/login for remote host" >&2
         exit 1
     }
-    tea milestone list $REPO_ARGS
+    prov_rc=0
+    tea milestone list $REPO_ARGS || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
 else
     echo "Error: Unknown platform"
     exit 1
diff --git a/packages/mosaic/framework/tools/git/pr-close.sh b/packages/mosaic/framework/tools/git/pr-close.sh
index 9fcb00f4..9a9dbdf7 100755
--- a/packages/mosaic/framework/tools/git/pr-close.sh
+++ b/packages/mosaic/framework/tools/git/pr-close.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 # pr-close.sh - Close a pull request without merging on GitHub or Gitea
-# Usage: pr-close.sh -n <pr_number> [-c <comment>]
+# Usage: pr-close.sh -n <pr_number> [-b <comment>]
+# (-c/--comment is a backward-compatible alias for -b/--body; R1/R4 2026-08-28)
 
 set -e
 
@@ -11,50 +12,80 @@ source "$SCRIPT_DIR/detect-platform.sh"
 PR_NUMBER=""
 COMMENT=""
 
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1), so a
+# caller or stop gate can tell an invocation defect from a delivery blocker.
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: pr-close.sh -n <pr_number> [-b <comment>] (see --help)" >&2
+    exit 2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -n|--number)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             PR_NUMBER="$2"
             shift 2
             ;;
-        -c|--comment)
+        -b|--body|-c|--comment)
+            # R1 (2026-08-28): --body is the canonical flag; -c/--comment stays
+            # a backward-compatible alias.
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             COMMENT="$2"
             shift 2
             ;;
         -h|--help)
-            echo "Usage: pr-close.sh -n <pr_number> [-c <comment>]"
+            echo "Usage: pr-close.sh -n <pr_number> [-b <comment>]"
             echo ""
             echo "Options:"
             echo "  -n, --number   PR number (required)"
-            echo "  -c, --comment  Comment before closing (optional)"
+            echo "  -b, --body     Comment before closing (optional; canonical)"
+            echo "  -c, --comment  Alias for --body"
             echo "  -h, --help     Show this help"
+            echo ""
+            echo "Exit codes: 0 success; 2 usage error (stderr); 1 provider/credential/verification failure."
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$PR_NUMBER" ]]; then
-    echo "Error: PR number is required (-n)"
-    exit 1
+    usage_error "PR number is required (-n/--number)"
 fi
 
 detect_platform >/dev/null
 
 if [[ "$PLATFORM" == "github" ]]; then
+    # R4: normalize provider failures to exit 1 (gh's own usage errors exit 2
+    # and would collide with the reserved usage-error status).
     if [[ -n "$COMMENT" ]]; then
-        gh pr comment "$PR_NUMBER" --body "$COMMENT"
+        gh_rc=0
+        gh pr comment "$PR_NUMBER" --body "$COMMENT" || gh_rc=$?
+        if [[ "$gh_rc" -ne 0 ]]; then
+            echo "Error: GitHub PR comment before close failed (gh exit $gh_rc)" >&2
+            exit 1
+        fi
+    fi
+    gh_rc=0
+    gh pr close "$PR_NUMBER" || gh_rc=$?
+    if [[ "$gh_rc" -ne 0 ]]; then
+        echo "Error: GitHub PR close failed (gh exit $gh_rc)" >&2
+        exit 1
     fi
-    gh pr close "$PR_NUMBER"
     echo "Closed GitHub PR #$PR_NUMBER"
 elif [[ "$PLATFORM" == "gitea" ]]; then
     if [[ -n "$COMMENT" ]]; then
-        tea pr comment "$PR_NUMBER" "$COMMENT" $(get_gitea_repo_args)
+        prov_rc=0
+        tea pr comment "$PR_NUMBER" "$COMMENT" $(get_gitea_repo_args) || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     fi
-    tea pr close "$PR_NUMBER" $(get_gitea_repo_args)
+    prov_rc=0
+    tea pr close "$PR_NUMBER" $(get_gitea_repo_args) || prov_rc=$?
+    [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
     echo "Closed Gitea PR #$PR_NUMBER"
 else
     echo "Error: Unknown platform"
diff --git a/packages/mosaic/framework/tools/git/pr-create.sh b/packages/mosaic/framework/tools/git/pr-create.sh
index 31a8dfa9..2226b091 100755
--- a/packages/mosaic/framework/tools/git/pr-create.sh
+++ b/packages/mosaic/framework/tools/git/pr-create.sh
@@ -135,37 +135,51 @@ Examples:
     $(basename "$0") -i 42 -b "Implements the feature described in #42"
     $(basename "$0") -t "WIP: New feature" --draft
 EOF
-    exit "${1:-1}"
+    exit "${1:-2}"
+}
+
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    usage >&2
 }
 
 # Parse arguments
 while [[ $# -gt 0 ]]; do
     case $1 in
         -t|--title)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             TITLE="$2"
             shift 2
             ;;
         -b|--body)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             BODY="$2"
             shift 2
             ;;
         -B|--base)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             BASE_BRANCH="$2"
             shift 2
             ;;
         -H|--head)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             HEAD_BRANCH="$2"
             shift 2
             ;;
         -l|--labels)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LABELS="$2"
             shift 2
             ;;
         -m|--milestone)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             MILESTONE="$2"
             shift 2
             ;;
         -i|--issue)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ISSUE="$2"
             shift 2
             ;;
@@ -266,7 +280,9 @@ case "$PLATFORM" in
         [[ -n "$LABELS" ]] && CMD+=(--label "$LABELS")
         [[ -n "$MILESTONE" ]] && CMD+=(--milestone "$MILESTONE")
         [[ "$DRAFT" == true ]] && CMD+=(--draft)
-        "${CMD[@]}"
+        prov_rc=0
+        "${CMD[@]}" || prov_rc=$?
+        [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         ;;
     gitea)
         # tea pull create syntax. Always pass --repo because tea repo inference
diff --git a/packages/mosaic/framework/tools/git/pr-edit.sh b/packages/mosaic/framework/tools/git/pr-edit.sh
index 47a12d8e..db520f7d 100755
--- a/packages/mosaic/framework/tools/git/pr-edit.sh
+++ b/packages/mosaic/framework/tools/git/pr-edit.sh
@@ -50,38 +50,45 @@ Options:
     -H, --host HOST        Explicit Gitea host (required with --repo off-host)
     -h, --help             Show this help message
 EOF
-    exit "${1:-1}"
+    exit "${1:-2}"
+}
+
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1).
+usage_error() {
+    echo "Error: $*" >&2
+    usage >&2
 }
 
 while [[ $# -gt 0 ]]; do
     case "$1" in
-        -n|--number) PR_NUMBER="${2:-}"; shift 2 ;;
-        -t|--title) TITLE="${2:-}"; shift 2 ;;
-        -b|--body) BODY="${2:-}"; shift 2 ;;
-        -B|--base) BASE_BRANCH="${2:-}"; shift 2 ;;
+        -n|--number) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; PR_NUMBER="${2:-}"; shift 2 ;;
+        -t|--title) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; TITLE="${2:-}"; shift 2 ;;
+        -b|--body) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; BODY="${2:-}"; shift 2 ;;
+        -B|--base) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; BASE_BRANCH="${2:-}"; shift 2 ;;
         --draft)
-            [[ "$DRAFT_MODE" != "ready" ]] || { echo "Error: --draft and --ready are mutually exclusive" >&2; exit 1; }
+            [[ "$DRAFT_MODE" != "ready" ]] || { echo "Error: --draft and --ready are mutually exclusive" >&2; exit 2; }
             DRAFT_MODE="draft"; shift ;;
         --ready)
-            [[ "$DRAFT_MODE" != "draft" ]] || { echo "Error: --draft and --ready are mutually exclusive" >&2; exit 1; }
+            [[ "$DRAFT_MODE" != "draft" ]] || { echo "Error: --draft and --ready are mutually exclusive" >&2; exit 2; }
             DRAFT_MODE="ready"; shift ;;
-        -l|--login) LOGIN_OVERRIDE="${2:-}"; shift 2 ;;
-        -r|--repo) REPO_OVERRIDE="${2:-}"; shift 2 ;;
-        -H|--host) HOST_OVERRIDE="${2:-}"; shift 2 ;;
+        -l|--login) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; LOGIN_OVERRIDE="${2:-}"; shift 2 ;;
+        -r|--repo) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; REPO_OVERRIDE="${2:-}"; shift 2 ;;
+        -H|--host) [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"; HOST_OVERRIDE="${2:-}"; shift 2 ;;
         -h|--help) usage 0 ;;
         *) echo "Unknown option: $1" >&2; usage ;;
     esac
 done
 
-[[ -n "$PR_NUMBER" ]] || { echo "Error: Pull request number is required (-n)" >&2; exit 1; }
-[[ "$PR_NUMBER" =~ ^[1-9][0-9]*$ ]] || { echo "Error: Pull request number must be a positive integer" >&2; exit 1; }
+[[ -n "$PR_NUMBER" ]] || { echo "Error: Pull request number is required (-n)" >&2; exit 2; }
+[[ "$PR_NUMBER" =~ ^[1-9][0-9]*$ ]] || { echo "Error: Pull request number must be a positive integer" >&2; exit 2; }
 if [[ -z "$TITLE" && -z "$BODY" && -z "$BASE_BRANCH" && -z "$DRAFT_MODE" ]]; then
     echo "Error: At least one edit option is required" >&2
-    exit 1
+    exit 2
 fi
 [[ -z "$REPO_OVERRIDE" || "$REPO_OVERRIDE" =~ ^[^/[:space:]]+/[^/[:space:]]+$ ]] || {
     echo "Error: --repo must be OWNER/REPO" >&2
-    exit 1
+    exit 2
 }
 
 if [[ -n "$HOST_OVERRIDE" || -n "$REPO_OVERRIDE" ]]; then
@@ -92,18 +99,24 @@ fi
 
 case "$PLATFORM" in
     github)
-        [[ -z "$LOGIN_OVERRIDE" ]] || { echo "Error: --login is only valid for Gitea" >&2; exit 1; }
+        [[ -z "$LOGIN_OVERRIDE" ]] || { echo "Error: --login is only valid for Gitea" >&2; exit 2; }
         if [[ -n "$TITLE" || -n "$BODY" || -n "$BASE_BRANCH" ]]; then
             CMD=(gh pr edit "$PR_NUMBER")
             [[ -n "$TITLE" ]] && CMD+=(--title "$TITLE")
             [[ -n "$BODY" ]] && CMD+=(--body "$BODY")
             [[ -n "$BASE_BRANCH" ]] && CMD+=(--base "$BASE_BRANCH")
-            "${CMD[@]}"
+            prov_rc=0
+            "${CMD[@]}" || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         fi
         if [[ "$DRAFT_MODE" == "draft" ]]; then
-            gh pr ready "$PR_NUMBER" --undo
+            prov_rc=0
+            gh pr ready "$PR_NUMBER" --undo || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         elif [[ "$DRAFT_MODE" == "ready" ]]; then
-            gh pr ready "$PR_NUMBER"
+            prov_rc=0
+            gh pr ready "$PR_NUMBER" || prov_rc=$?
+            [[ "$prov_rc" -eq 0 ]] || { echo "Error: provider command failed (exit ${prov_rc}; provider failure, not a usage error)" >&2; exit 1; }
         fi
         ;;
     gitea)
diff --git a/packages/mosaic/framework/tools/git/pr-review.sh b/packages/mosaic/framework/tools/git/pr-review.sh
index b131f385..e468222d 100755
--- a/packages/mosaic/framework/tools/git/pr-review.sh
+++ b/packages/mosaic/framework/tools/git/pr-review.sh
@@ -43,60 +43,92 @@ LOGIN_OVERRIDE=""
 REPO_OVERRIDE=""
 HOST_OVERRIDE=""
 
+# Usage-error contract (R4, 2026-08-28): usage errors print to STDERR and exit 2,
+# distinct from provider, credential, and verification failures (exit 1), so a
+# caller or stop gate can tell an invocation defect from a delivery blocker.
+usage_error() {
+    echo "Error: $*" >&2
+    echo "Usage: pr-review.sh -n <pr_number> -a <action> [-b <comment>] (see --help)" >&2
+    exit 2
+}
+
 while [[ $# -gt 0 ]]; do
     case $1 in
         -n|--number)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             PR_NUMBER="$2"
             shift 2
             ;;
         -a|--action)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             ACTION="$2"
             shift 2
             ;;
-        -c|--comment)
+        -b|--body|-c|--comment)
+            # R1 (2026-08-28): --body is the canonical flag; -c/--comment stays
+            # a backward-compatible alias.
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             COMMENT="$2"
             shift 2
             ;;
         -l|--login)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             LOGIN_OVERRIDE="$2"
             shift 2
             ;;
         -r|--repo)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             REPO_OVERRIDE="$2"
             shift 2
             ;;
         -H|--host)
+            [[ $# -ge 2 && "$2" != - && "$2" != --* && ! "$2" =~ ^-[[:alnum:]] ]] || usage_error "option $1 requires a value (option-like values are rejected; bare - is reserved)"
             HOST_OVERRIDE="$2"
             shift 2
             ;;
         -h|--help)
-            echo "Usage: pr-review.sh -n <pr_number> -a <action> [-c <comment>] [--login <name>] [-r owner/repo] [-H host]"
+            echo "Usage: pr-review.sh -n <pr_number> -a <action> [-b <comment>] [--login <name>] [-r owner/repo] [-H host]"
             echo ""
             echo "Options:"
             echo "  -n, --number   PR number (required)"
             echo "  -a, --action   Review action: approve, request-changes, comment (required)"
-            echo "  -c, --comment  Review comment (required for request-changes)"
+            echo "  -b, --body     Review comment (required for request-changes; canonical)"
+            echo "  -c, --comment  Alias for --body"
             echo "  -l, --login    Override the detected Gitea tea login (approve/request-changes only)"
             echo "  -r, --repo     Explicit owner/repo slug (skips git-remote slug inference)"
             echo "  -H, --host     Explicit Gitea host (skips remote-host inference)"
             echo "  -h, --help     Show this help"
+            echo ""
+            echo "Exit codes: 0 success; 2 usage error (stderr); 1 provider/credential/verification failure."
             exit 0
             ;;
         *)
-            echo "Unknown option: $1"
-            exit 1
+            usage_error "unknown option: $1"
             ;;
     esac
 done
 
 if [[ -z "$PR_NUMBER" ]]; then
-    echo "Error: PR number is required (-n)"
-    exit 1
+    usage_error "PR number is required (-n/--number)"
 fi
 
 if [[ -z "$ACTION" ]]; then
-    echo "Error: Action is required (-a): approve, request-changes, comment"
-    exit 1
+    usage_error "Action is required (-a/--action): approve, request-changes, comment"
+fi
+
+# Validate the action BEFORE any provider contact (codex review of PR #1464:
+# an unsupported --action previously reached platform detection and could
+# touch the provider before failing with a provider-class status).
+case "$ACTION" in
+    approve|request-changes|comment) ;;
+    *) usage_error "unknown action '$ACTION': approve, request-changes, comment" ;;
+esac
+
+# Body-required actions fail fast too (codex follow-up on PR #1464):
+# request-changes and comment both require a body; validate before any
+# provider contact.
+if [[ ( "$ACTION" == "request-changes" || "$ACTION" == "comment" ) && -z "$COMMENT" ]]; then
+    usage_error "comment required for $ACTION (-b/--body)"
 fi
 
 if [[ -n "$REPO_OVERRIDE" ]]; then
@@ -679,15 +711,18 @@ PY
 if [[ "$PLATFORM" == "github" ]]; then
     case $ACTION in
         approve)
-            gh pr review "$PR_NUMBER" --approve ${COMMENT:+--body "$COMMENT"}
+            gh_rc=0
+            gh pr review "$PR_NUMBER" --approve ${COMMENT:+--body "$COMMENT"} || gh_rc=$?
+            [[ "$gh_rc" -eq 0 ]] || { echo "Error: GitHub approve failed (gh exit $gh_rc; provider failure, not a usage error)" >&2; exit 1; }
             echo "Approved GitHub PR #$PR_NUMBER"
             ;;
         request-changes)
             if [[ -z "$COMMENT" ]]; then
-                echo "Error: Comment required for request-changes"
-                exit 1
+                usage_error "comment required for request-changes (-b/--body)"
             fi
-            gh pr review "$PR_NUMBER" --request-changes --body "$COMMENT"
+            gh_rc=0
+            gh pr review "$PR_NUMBER" --request-changes --body "$COMMENT" || gh_rc=$?
+            [[ "$gh_rc" -eq 0 ]] || { echo "Error: GitHub request-changes failed (gh exit $gh_rc; provider failure, not a usage error)" >&2; exit 1; }
             echo "Requested changes on GitHub PR #$PR_NUMBER"
             ;;
         comment)
@@ -695,12 +730,13 @@ if [[ "$PLATFORM" == "github" ]]; then
                 echo "Error: Comment required"
                 exit 1
             fi
-            gh pr review "$PR_NUMBER" --comment --body "$COMMENT"
+            gh_rc=0
+            gh pr review "$PR_NUMBER" --comment --body "$COMMENT" || gh_rc=$?
+            [[ "$gh_rc" -eq 0 ]] || { echo "Error: GitHub review comment failed (gh exit $gh_rc; provider failure, not a usage error)" >&2; exit 1; }
             echo "Added review comment to GitHub PR #$PR_NUMBER"
             ;;
         *)
-            echo "Error: Unknown action: $ACTION"
-            exit 1
+            usage_error "unknown action: $ACTION"
             ;;
     esac
 elif [[ "$PLATFORM" == "gitea" ]]; then
@@ -738,8 +774,7 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
             ;;
         request-changes)
             if [[ -z "$COMMENT" ]]; then
-                echo "Error: Comment required for request-changes"
-                exit 1
+                usage_error "comment required for request-changes (-b/--body)"
             fi
             # Best-effort host for credential resolution only (gitea_resolve_api_for_login
             # below re-derives the real host from HOST_OVERRIDE/remote independently and
@@ -794,8 +829,7 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
             echo "Added and verified comment on Gitea PR #$PR_NUMBER (comment ID $comment_id)"
             ;;
         *)
-            echo "Error: Unknown action: $ACTION"
-            exit 1
+            usage_error "unknown action: $ACTION"
             ;;
     esac
 else
diff --git a/packages/mosaic/framework/tools/git/test-issue-assign-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-assign-usage-contract.sh
new file mode 100755
index 00000000..5c73537c
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-assign-usage-contract.sh
@@ -0,0 +1,154 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-assign.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-assign-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-assign.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-assign.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-assign.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -i exits 2"
+expect_stderr "Issue number is required" "missing -i message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -i -a -l -m --issue --assignee --labels --milestone; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -i 5 -a --help
+expect_rc 2 "short flag value rejected" -i 5 -a -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -a; do
+    rc=0
+    run_wrapper_sandboxed -i 5 "$flag" "value" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+# 6b. Provider-exit normalization (codex PR #1464): a provider stub exiting
+# 2 (its own usage-error status) must surface as wrapper exit 1, never 2.
+GH_REPO="$WORK_DIR/repo-gh"
+mkdir -p "$GH_REPO"
+git -C "$GH_REPO" init -q
+git -C "$GH_REPO" remote add origin https://github.com/acme/widgets.git
+cat > "$BIN_DIR/gh" <<GHSTUB
+#!/usr/bin/env bash
+echo "gh \$*" >> "$PROBE_LOG"
+if [[ "\$1 \$2" == "issue edit" ]]; then exit 2; fi
+exit 0
+GHSTUB
+chmod +x "$BIN_DIR/gh"
+rc=0
+(
+    cd "$GH_REPO"
+    PATH="$BIN_DIR:$PATH" MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+        "$SCRIPT_DIR/issue-assign.sh" -i 5 -a someone >"$OUT_FILE" 2>"$ERR_FILE"
+) || rc=$?
+[[ "$rc" -eq 1 ]] || fail "GitHub path: gh exit 2 must normalize to wrapper exit 1 (got $rc)"
+grep -q "provider" "$ERR_FILE" || fail "GitHub path: normalized provider error missing from stderr"
+
+echo "issue-assign.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-issue-close-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-close-usage-contract.sh
new file mode 100755
index 00000000..b0ef6ae4
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-close-usage-contract.sh
@@ -0,0 +1,136 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-close.sh (R1/R4, 2026-08-28).
+#
+# R4: usage errors print to STDERR and exit 2, distinct from provider,
+# credential, and verification failures (exit 1). R1: -b/--body is the
+# canonical comment flag; -c/--comment remains a compatible alias.
+# The comment is OPTIONAL here (an issue may close without one), so unlike
+# issue-comment there is no missing-comment arm.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-close-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 0
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-close.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-close.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-close.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "unknown option" "unknown option names itself on stderr"
+
+# 3. Missing required issue number: rc 2, stderr.
+expect_rc 2 "missing -i exits 2"
+expect_stderr "issue number is required" "missing -i message on stderr"
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -i -b -c --issue --body --comment; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -i 5 -b --help
+expect_rc 2 "short flag value rejected" -i 5 -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b -c; do
+    rc=0
+    run_wrapper_sandboxed -i 5 "$flag" "closing note" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Sandbox arms may issue DETECTION reads only (tea login list via the
+# stub); no gh/curl write or read may occur.
+if grep -Ev '^(gh|tea|curl) login list' "$PROBE_LOG" | grep -q .; then
+    echo "FAIL: a sandbox arm performed a non-detection provider request:" >&2
+    grep -Ev '^(gh|tea|curl) login list' "$PROBE_LOG" >&2
+    exit 1
+fi
+if grep -qE '^(gh|curl)' "$PROBE_LOG"; then
+    echo "FAIL: gh or curl was invoked during a sandbox arm:" >&2
+    grep -E '^(gh|curl)' "$PROBE_LOG" >&2
+    exit 1
+fi
+
+echo "issue-close.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-issue-comment-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-comment-usage-contract.sh
index a1be441a..d80a89a4 100755
--- a/packages/mosaic/framework/tools/git/test-issue-comment-usage-contract.sh
+++ b/packages/mosaic/framework/tools/git/test-issue-comment-usage-contract.sh
@@ -97,7 +97,7 @@ expect_rc() { # expect_rc <want> <desc> <args...>
 }
 
 expect_stderr() { # expect_stderr <pattern> <desc>
-    grep -q "$1" "$ERR_FILE" || fail "$desc: stderr missing '$1'"
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
 }
 
 # 1. Help exits 0 and prints usage on stdout.
@@ -124,6 +124,13 @@ for flag in -i -b -c -l --issue --body --comment --login; do
     expect_stderr "requires a value" "value-less $flag message on stderr"
 done
 
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -i 5 -b --help
+expect_rc 2 "short flag value rejected" -i 5 -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
 # 6. Alias acceptance at parse level: both -b and -c carry a value past
 # parsing; the wrapper then fails at platform detection (not a git repo)
 # nonzero but NOT as a usage error (rc must not be 2).
diff --git a/packages/mosaic/framework/tools/git/test-issue-create-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-create-usage-contract.sh
new file mode 100755
index 00000000..1cdbfc7a
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-create-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-create.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-create-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-create.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-create.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-create.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -t exits 2"
+expect_stderr "Title is required" "missing -t message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -t -b -l -m --title --body --labels --milestone; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -t smoke -b --help
+expect_rc 2 "short flag value rejected" -t smoke -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b; do
+    rc=0
+    run_wrapper_sandboxed -t "smoke" "$flag" "value" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "issue-create.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-issue-edit-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-edit-usage-contract.sh
new file mode 100755
index 00000000..0f939f9d
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-edit-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-edit.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-edit-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-edit.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-edit.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-edit.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "unknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -i exits 2"
+expect_stderr "issue number is required" "missing -i message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -i -t -b -l -m --issue --title --body --labels --milestone; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -i 5 -b --help
+expect_rc 2 "short flag value rejected" -i 5 -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b; do
+    rc=0
+    run_wrapper_sandboxed -i 5 "$flag" "value" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "issue-edit.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-issue-list-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-list-usage-contract.sh
new file mode 100755
index 00000000..75aaae46
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-list-usage-contract.sh
@@ -0,0 +1,130 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-list.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-list-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-list.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-list.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-list.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -s -l -m -a -n -r --state --label --milestone --assignee --limit --repo; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -s --help
+expect_rc 2 "short flag value rejected" -s -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -s; do
+    rc=0
+    run_wrapper_sandboxed -s open >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "issue-list.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-issue-reopen-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-reopen-usage-contract.sh
new file mode 100755
index 00000000..ff7e7343
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-reopen-usage-contract.sh
@@ -0,0 +1,136 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-reopen.sh (R1/R4, 2026-08-28).
+#
+# R4: usage errors print to STDERR and exit 2, distinct from provider,
+# credential, and verification failures (exit 1). R1: -b/--body is the
+# canonical comment flag; -c/--comment remains a compatible alias.
+# The comment is OPTIONAL here (an issue may close without one), so unlike
+# issue-comment there is no missing-comment arm.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-reopen-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 0
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-reopen.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-reopen.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-reopen.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "unknown option" "unknown option names itself on stderr"
+
+# 3. Missing required issue number: rc 2, stderr.
+expect_rc 2 "missing -i exits 2"
+expect_stderr "issue number is required" "missing -i message on stderr"
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -i -b -c --issue --body --comment; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -i 5 -b --help
+expect_rc 2 "short flag value rejected" -i 5 -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b -c; do
+    rc=0
+    run_wrapper_sandboxed -i 5 "$flag" "closing note" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Sandbox arms may issue DETECTION reads only (tea login list via the
+# stub); no gh/curl write or read may occur.
+if grep -Ev '^(gh|tea|curl) login list' "$PROBE_LOG" | grep -q .; then
+    echo "FAIL: a sandbox arm performed a non-detection provider request:" >&2
+    grep -Ev '^(gh|tea|curl) login list' "$PROBE_LOG" >&2
+    exit 1
+fi
+if grep -qE '^(gh|curl)' "$PROBE_LOG"; then
+    echo "FAIL: gh or curl was invoked during a sandbox arm:" >&2
+    grep -E '^(gh|curl)' "$PROBE_LOG" >&2
+    exit 1
+fi
+
+echo "issue-reopen.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-issue-view-usage-contract.sh b/packages/mosaic/framework/tools/git/test-issue-view-usage-contract.sh
new file mode 100755
index 00000000..d2ff9182
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-issue-view-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for issue-view.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-view-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/issue-view.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/issue-view.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: issue-view.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -i exits 2"
+expect_stderr "Issue number is required" "missing -i message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -i --issue; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -i --help
+expect_rc 2 "short flag value rejected" -i -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -i; do
+    rc=0
+    run_wrapper_sandboxed -i 5 >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "issue-view.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-lane-brief-pr-linkage.sh b/packages/mosaic/framework/tools/git/test-lane-brief-pr-linkage.sh
old mode 100644
new mode 100755
diff --git a/packages/mosaic/framework/tools/git/test-lane-brief-usage-contract.sh b/packages/mosaic/framework/tools/git/test-lane-brief-usage-contract.sh
new file mode 100755
index 00000000..64c08ebc
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-lane-brief-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for lane-brief.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/lane-brief-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/lane-brief.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/lane-brief.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "owner/repo" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -r exits 2"
+expect_stderr "required" "missing -r message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -r -m -l -L -n --repo --milestone --label --login --limit; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -r owner/repo -m --help
+expect_rc 2 "short flag value rejected" -r owner/repo -m -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -r; do
+    rc=0
+    run_wrapper_sandboxed -r owner/repo >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "lane-brief.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-milestone-close-usage-contract.sh b/packages/mosaic/framework/tools/git/test-milestone-close-usage-contract.sh
new file mode 100755
index 00000000..c7f38771
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-milestone-close-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for milestone-close.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/milestone-close-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/milestone-close.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/milestone-close.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: milestone-close.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -t exits 2"
+expect_stderr "Milestone title is required" "missing -t message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -t --title; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -t --help --help
+expect_rc 2 "short flag value rejected" -t --help -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -t; do
+    rc=0
+    run_wrapper_sandboxed -t "smoke" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "milestone-close.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-milestone-create-usage-contract.sh b/packages/mosaic/framework/tools/git/test-milestone-create-usage-contract.sh
new file mode 100755
index 00000000..e267f9dc
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-milestone-create-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for milestone-create.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/milestone-create-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/milestone-create.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/milestone-create.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: milestone-create.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -t exits 2"
+expect_stderr "Title is required" "missing -t message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -t -d --due --title --desc; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -t smoke -d --help
+expect_rc 2 "short flag value rejected" -t smoke -d -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -t; do
+    rc=0
+    run_wrapper_sandboxed -t "smoke" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "milestone-create.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-milestone-list-usage-contract.sh b/packages/mosaic/framework/tools/git/test-milestone-list-usage-contract.sh
new file mode 100755
index 00000000..e2456405
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-milestone-list-usage-contract.sh
@@ -0,0 +1,153 @@
+#!/usr/bin/env bash
+# Usage-error contract for milestone-list.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/milestone-list-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/milestone-list.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/milestone-list.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: milestone-list.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -s --state; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -s --help
+expect_rc 2 "short flag value rejected" -s -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -s; do
+    rc=0
+    run_wrapper_sandboxed -s open >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+# 6b. Provider-exit normalization (codex PR #1464): a provider stub exiting
+# 2 (its own usage-error status) must surface as wrapper exit 1, never 2.
+GH_REPO="$WORK_DIR/repo-gh"
+mkdir -p "$GH_REPO"
+git -C "$GH_REPO" init -q
+git -C "$GH_REPO" remote add origin https://github.com/acme/widgets.git
+cat > "$BIN_DIR/gh" <<GHSTUB
+#!/usr/bin/env bash
+echo "gh \$*" >> "$PROBE_LOG"
+if [[ "\$1" == "api" ]]; then exit 2; fi
+exit 0
+GHSTUB
+chmod +x "$BIN_DIR/gh"
+rc=0
+(
+    cd "$GH_REPO"
+    PATH="$BIN_DIR:$PATH" MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+        "$SCRIPT_DIR/milestone-list.sh" >"$OUT_FILE" 2>"$ERR_FILE"
+) || rc=$?
+[[ "$rc" -eq 1 ]] || fail "GitHub path: gh exit 2 must normalize to wrapper exit 1 (got $rc)"
+grep -q "provider" "$ERR_FILE" || fail "GitHub path: normalized provider error missing from stderr"
+
+echo "milestone-list.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-pr-close-usage-contract.sh b/packages/mosaic/framework/tools/git/test-pr-close-usage-contract.sh
new file mode 100755
index 00000000..6d380e59
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-pr-close-usage-contract.sh
@@ -0,0 +1,133 @@
+#!/usr/bin/env bash
+# Usage-error contract for pr-close.sh (R1/R4, 2026-08-28).
+#
+# R4: usage errors print to STDERR and exit 2, distinct from provider,
+# credential, and verification failures (exit 1). R1: -b/--body is the
+# canonical comment flag; -c/--comment remains a compatible alias.
+# The comment is OPTIONAL here (an issue may close without one), so unlike
+# issue-comment there is no missing-comment arm.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-close-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/pr-close.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/pr-close.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: pr-close.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "unknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -n exits 2"
+expect_stderr "PR number is required" "missing -n message on stderr"
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -n -b -c --number --body --comment; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -n 5 -b --help
+expect_rc 2 "short flag value rejected" -n 5 -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b -c; do
+    rc=0
+    run_wrapper_sandboxed -n 5 "$flag" "closing note" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "pr-close.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-pr-create-usage-contract.sh b/packages/mosaic/framework/tools/git/test-pr-create-usage-contract.sh
new file mode 100755
index 00000000..ad23472c
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-pr-create-usage-contract.sh
@@ -0,0 +1,132 @@
+#!/usr/bin/env bash
+# Usage-error contract for pr-create.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-create-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/pr-create.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/pr-create.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: pr-create.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -t exits 2"
+expect_stderr "Title is required" "missing -t message on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -t -b -B -H -l -m -i --title --body --base --head --labels --milestone --issue; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -t smoke -b --help
+expect_rc 2 "short flag value rejected" -t smoke -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b; do
+    rc=0
+    run_wrapper_sandboxed -t "smoke" "$flag" "value" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "pr-create.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-pr-edit-usage-contract.sh b/packages/mosaic/framework/tools/git/test-pr-edit-usage-contract.sh
new file mode 100755
index 00000000..71448ca9
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-pr-edit-usage-contract.sh
@@ -0,0 +1,140 @@
+#!/usr/bin/env bash
+# Usage-error contract for pr-edit.sh (R4, 2026-08-28).
+#
+# issue-edit already uses long-flag-first parsing (-i/--issue, -t/--title,
+# -b/--body, -l/--labels, -m/--milestone); this adds the rc=2 usage-error
+# contract, value checks, and the no-provider-contact proof. Required: -i.
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-edit-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/pr-edit.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/pr-edit.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: pr-edit.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "[Uu]nknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -n exits 2"
+expect_stderr "Pull request number is required" "missing -n message on stderr"
+expect_rc 2 "no edit option exits 2" -n 5
+expect_stderr "At least one edit option is required" "no-edit-option message on stderr"
+expect_rc 2 "non-integer PR number exits 2" -n abc -t x
+expect_stderr "positive integer" "integer check on stderr"
+expect_rc 2 "mutually exclusive draft/ready exits 2" -n 5 --draft --ready
+expect_stderr "mutually exclusive" "mutual exclusion on stderr"
+expect_rc 2 "bad repo format exits 2" -n 5 -t x -r not-a-slug
+expect_stderr "OWNER/REPO" "repo format on stderr"
+
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -n -t -b -B -l -r -H --number --title --body --base --login --repo --host; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -n 5 -t smoke -b --help
+expect_rc 2 "short flag value rejected" -n 5 -t smoke -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b; do
+    rc=0
+    run_wrapper_sandboxed -n 5 "$flag" "value" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "pr-edit.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/framework/tools/git/test-pr-review-gitea-comment.sh b/packages/mosaic/framework/tools/git/test-pr-review-gitea-comment.sh
old mode 100644
new mode 100755
diff --git a/packages/mosaic/framework/tools/git/test-pr-review-repo-host-override.sh b/packages/mosaic/framework/tools/git/test-pr-review-repo-host-override.sh
index f5699ce4..789fa410 100755
--- a/packages/mosaic/framework/tools/git/test-pr-review-repo-host-override.sh
+++ b/packages/mosaic/framework/tools/git/test-pr-review-repo-host-override.sh
@@ -218,7 +218,7 @@ if grep -q 'Unknown option' "$OUTPUT_FILE"; then
     cat "$OUTPUT_FILE" >&2
     exit 1
 fi
-grep -q 'Unknown action: bogus-action' "$OUTPUT_FILE"
+grep -q "unknown action 'bogus-action'" "$OUTPUT_FILE"
 
 # --- Case 2: -h/--help documents both overrides.
 HELP_TEXT="$("$SCRIPT_DIR/pr-review.sh" -h)"
diff --git a/packages/mosaic/framework/tools/git/test-pr-review-usage-contract.sh b/packages/mosaic/framework/tools/git/test-pr-review-usage-contract.sh
new file mode 100755
index 00000000..13dbf50b
--- /dev/null
+++ b/packages/mosaic/framework/tools/git/test-pr-review-usage-contract.sh
@@ -0,0 +1,148 @@
+#!/usr/bin/env bash
+# Usage-error contract for pr-review.sh (R1/R4, 2026-08-28).
+#
+# R4: usage errors print to STDERR and exit 2, distinct from provider,
+# credential, and verification failures (exit 1). R1: -b/--body is the
+# canonical comment flag; -c/--comment remains a compatible alias.
+# Required: -n AND -a. The comment is required only for the
+# request-changes action (semantic usage check, also rc 2).
+#
+# Arms:
+#   1. --help and -h exit 0 and print usage.
+#   2. Unknown option exits 2 with the message on stderr.
+#   3. Missing required -i exits 2 (stderr).
+#   4. A value-less flag (-i -b -c and long forms) exits 2 (stderr).
+#   5. -b and -c both pass parsing (sandboxed runner: the run then fails
+#      at credential resolution, nonzero and NOT 2) — no real token is
+#      ever read and no provider is contacted.
+#   6. No arm performs any provider request (PATH shims record every
+#      invocation; the probe log must stay empty).
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-review-usage}"
+BIN_DIR="$WORK_DIR/bin"
+PROBE_LOG="$WORK_DIR/provider-probes.log"
+OUT_FILE="$WORK_DIR/out.log"
+ERR_FILE="$WORK_DIR/err.log"
+
+cleanup() {
+    rm -rf "$WORK_DIR"
+}
+trap cleanup EXIT
+
+mkdir -p "$BIN_DIR"
+: > "$PROBE_LOG"
+
+# Unlike the issue suites, these stubs FAIL (exit 99): pr-close has an
+# API fallback that treats a successful curl as a closed PR, so exit-0
+# stubs would let the sandbox arms "succeed" (measured 2026-08-28).
+for tool in gh tea curl; do
+    cat > "$BIN_DIR/$tool" <<STUB
+#!/usr/bin/env bash
+echo "$tool \$*" >> "$PROBE_LOG"
+exit 99
+STUB
+    chmod +x "$BIN_DIR/$tool"
+done
+
+run_wrapper() {
+    ( cd "$WORK_DIR" && PATH="$BIN_DIR:$PATH" "$SCRIPT_DIR/pr-review.sh" "$@" )
+}
+
+# Hermetic variant: neutralizes every identity/credential source the wrapper
+# consults so parse-acceptance arms fail at credential resolution in ANY cwd
+# repo (see test-issue-comment-usage-contract.sh for the measured incident).
+run_wrapper_sandboxed() {
+    mkdir -p "$WORK_DIR/home" "$WORK_DIR/xdg"
+    (
+        cd "$WORK_DIR"
+        PATH="$BIN_DIR:$PATH" HOME="$WORK_DIR/home" XDG_CONFIG_HOME="$WORK_DIR/xdg" \
+            MOSAIC_GIT_IDENTITY="" MOSAIC_BRAIN_HOME="" \
+            "$SCRIPT_DIR/pr-review.sh" "$@"
+    )
+}
+
+fail() {
+    echo "FAIL: $*" >&2
+    echo "--- stderr ---" >&2
+    cat "$ERR_FILE" >&2
+    exit 1
+}
+
+expect_rc() { # expect_rc <want> <desc> <args...>
+    local want="$1" desc="$2" rc=0
+    shift 2
+    run_wrapper "$@" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -eq "$want" ]] || fail "$desc: rc=$rc, want $want"
+}
+
+expect_stderr() { # expect_stderr <pattern> <desc>
+    grep -q "$1" "$ERR_FILE" || fail "$2: stderr missing '$1'"
+}
+
+# 1. Help exits 0 and prints usage.
+expect_rc 0 "--help exits 0" --help
+grep -q "Usage: pr-review.sh" "$OUT_FILE" || fail "--help did not print usage"
+expect_rc 0 "-h exits 0" -h
+
+# 2. Unknown option: rc 2, stderr.
+expect_rc 2 "unknown option exits 2" --bogus
+expect_stderr "unknown option" "unknown option names itself on stderr"
+
+# 3. Missing required PR number: rc 2, stderr.
+expect_rc 2 "missing -n exits 2"
+expect_stderr "PR number is required" "missing -n message on stderr"
+expect_rc 2 "missing -a exits 2" -n 5
+expect_stderr "Action is required" "missing -a message on stderr"
+expect_rc 2 "request-changes without comment exits 2" -n 5 -a request-changes
+expect_stderr "comment required for request-changes" "request-changes message on stderr"
+expect_rc 2 "comment without body exits 2 pre-detection" -n 5 -a comment
+expect_stderr "comment required for comment" "comment-without-body message on stderr"
+expect_rc 2 "invalid action exits 2 pre-detection" -n 5 -a bogus
+expect_stderr "unknown action" "invalid action message on stderr"
+# Invalid-action arms must not contact any provider (validation precedes
+# detect_platform): probe log empty at this point.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: an invalid-action arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 4. Value-less flags: rc 2 with "requires a value" on stderr.
+for flag in -n -a -b -c -l -r --number --action --body --comment --login --repo; do
+    expect_rc 2 "value-less $flag exits 2" "$flag"
+    expect_stderr "requires a value" "value-less $flag message on stderr"
+done
+
+# 4a. An option-like value is a MISSING value, not a value (codex PR #1464:
+# -b --help previously consumed --help as the body and performed the write).
+expect_rc 2 "option-like value rejected" -n 5 -a comment -b --help
+expect_rc 2 "short flag value rejected" -n 5 -a comment -b -h
+expect_stderr "requires a value" "short flag value message on stderr"
+expect_stderr "requires a value" "option-like value message on stderr"
+
+# 4b. Parser-failure arms (1-4) must have performed ZERO provider contact.
+if [[ -s "$PROBE_LOG" ]]; then
+    echo "FAIL: a parser-failure arm contacted a provider:" >&2
+    cat "$PROBE_LOG" >&2
+    exit 1
+fi
+
+# 5. Alias acceptance under the sandbox: both -b and -c carry a value past
+#    parsing; the run fails at credential resolution nonzero and NOT 2.
+for flag in -b -c; do
+    rc=0
+    run_wrapper_sandboxed -n 5 -a comment "$flag" "review note" >"$OUT_FILE" 2>"$ERR_FILE" || rc=$?
+    [[ "$rc" -ne 0 ]] || fail "$flag arm unexpectedly succeeded in the sandbox"
+    [[ "$rc" -ne 2 ]] || fail "$flag arm misclassified credential failure as a usage error"
+done
+
+# 6. Post-sandbox provider assertions are intentionally NOT applied here:
+# pr-close's gitea path attempts a tea WRITE (tea pr comment) when a
+# comment parses, then falls back to the API. Hermeticity for this
+# wrapper comes from the FAILING stubs (exit 99), not from non-contact —
+# the arm above proves only parse acceptance and non-usage classification.
+# Parser-failure arms (1-4) remain zero-contact (asserted at 4b).
+
+echo "pr-review.sh usage-contract regression passed (R1/R4)"
diff --git a/packages/mosaic/package.json b/packages/mosaic/package.json
index ce1a3740..b047a4e8 100644
--- a/packages/mosaic/package.json
+++ b/packages/mosaic/package.json
@@ -25,7 +25,7 @@
     "lint": "eslint src",
     "typecheck": "tsc --noEmit",
     "test": "vitest run --passWithNoTests && pnpm run test:framework-shell",
-    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 framework/tools/quality/scripts/test-framework-drift-check.py && bash framework/tools/quality/scripts/test-framework-drift-doctor.sh && bash framework/systemd/user/test-fleet-units.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/promotion_binding_unittest.py && python3 src/lease-broker/promotion_trigger_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/receipt_observer_client_unittest.py && python3 src/lease-broker/invariant_r_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/lease-broker/revoke_noop_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-edit.sh && bash framework/tools/git/test-pr-create-fallback-default-base.sh && bash framework/tools/git/test-repo-decl-consumption.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-no-status.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-ci-queue-wait-no-ci-expected.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-no-ci-expected.sh && bash framework/tools/git/test-pr-merge-fork-ci-status.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-pr-merge-message-field.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/git/test-issue-comment-usage-contract.sh && bash framework/tools/git/test-issue-comment-readback.sh && bash framework/tools/git/test-explain-diagnostic-status-neutral.sh && bash framework/tools/git/test-detect-platform-outside-repo.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/_scripts/test-mosaic-init-rce.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh && bash framework/tools/glpi/test-list-http-status.sh && bash framework/tools/orchestrator/test-board-roll.sh && bash framework/tools/woodpecker/test-ci-wait-exit-matrix.sh && bash framework/tools/_scripts/test-fleet-transport-check.sh && bash framework/tools/_scripts/test-brain-home-check.sh && bash framework/tools/_scripts/test-structure-anchor-check.sh && bash framework/tools/fleet/test-agent-session-broker-preflight.sh && bash framework/tools/fleet/test-agent-session-legacy-socket-guard.sh && bash framework/tools/git/test-grant-reviewer.sh"
+    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 framework/tools/quality/scripts/test-framework-drift-check.py && bash framework/tools/quality/scripts/test-framework-drift-doctor.sh && bash framework/systemd/user/test-fleet-units.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/promotion_binding_unittest.py && python3 src/lease-broker/promotion_trigger_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/receipt_observer_client_unittest.py && python3 src/lease-broker/invariant_r_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/lease-broker/revoke_noop_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-edit.sh && bash framework/tools/git/test-pr-create-fallback-default-base.sh && bash framework/tools/git/test-repo-decl-consumption.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-no-status.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-ci-queue-wait-no-ci-expected.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-no-ci-expected.sh && bash framework/tools/git/test-pr-merge-fork-ci-status.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-pr-merge-message-field.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/git/test-issue-comment-usage-contract.sh && bash framework/tools/git/test-issue-comment-readback.sh && bash framework/tools/git/test-issue-close-usage-contract.sh && bash framework/tools/git/test-issue-reopen-usage-contract.sh && bash framework/tools/git/test-pr-close-usage-contract.sh && bash framework/tools/git/test-pr-review-usage-contract.sh && bash framework/tools/git/test-issue-edit-usage-contract.sh && bash framework/tools/git/test-issue-create-usage-contract.sh && bash framework/tools/git/test-pr-edit-usage-contract.sh && bash framework/tools/git/test-pr-create-usage-contract.sh && bash framework/tools/git/test-issue-assign-usage-contract.sh && bash framework/tools/git/test-milestone-close-usage-contract.sh && bash framework/tools/git/test-milestone-list-usage-contract.sh && bash framework/tools/git/test-issue-view-usage-contract.sh && bash framework/tools/git/test-issue-list-usage-contract.sh && bash framework/tools/git/test-milestone-create-usage-contract.sh && bash framework/tools/git/test-lane-brief-usage-contract.sh && bash framework/tools/git/test-explain-diagnostic-status-neutral.sh && bash framework/tools/git/test-detect-platform-outside-repo.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/_scripts/test-mosaic-init-rce.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh && bash framework/tools/glpi/test-list-http-status.sh && bash framework/tools/orchestrator/test-board-roll.sh && bash framework/tools/woodpecker/test-ci-wait-exit-matrix.sh && bash framework/tools/_scripts/test-fleet-transport-check.sh && bash framework/tools/_scripts/test-brain-home-check.sh && bash framework/tools/_scripts/test-structure-anchor-check.sh && bash framework/tools/fleet/test-agent-session-broker-preflight.sh && bash framework/tools/fleet/test-agent-session-legacy-socket-guard.sh && bash framework/tools/git/test-grant-reviewer.sh"
   },
   "dependencies": {
     "@mosaicstack/brain": "workspace:*",