fix(#1356): tea login resolution fails closed on a declared git identity (#1361)

Co-authored-by: fred <[email protected]>

packages/mosaic/framework/tools/git/README.md

@@ -102,6 +102,36 @@ of their own — `MOSAIC_GIT_IDENTITY=<id>` with a provisioned slot. There is de
 environment variable that restores the fallback; one would reintroduce exactly the
 substitution this removes.
 
+### The tea path: login resolution (#1356)
+
+The wrappers that go through `tea` (`issue-list.sh`, `pr-list.sh`, `pr-view.sh`,
+`lane-brief.sh`, and the tea half of `issue-close.sh`) cannot use a token directly: tea
+0.14 only acts as a **login** already stored in `~/.config/tea/config.yml`. Those wrappers
+therefore resolve a login name, not a token, and the resolution follows the same identity
+as above:
+
+1. Resolve the identity (`MOSAIC_GIT_IDENTITY`, then `git config mosaic.gitIdentity`).
+2. Derive the Gitea instance from the repo host (`git.mosaicstack.dev` → `mosaicstack`,
+   `git.uscllc.com` → `usc`), or from the owner when `--repo owner/name` is given.
+3. The canonical login is `<instance>-<identity>`. If tea has it, that login acts.
+4. If the identity is set but that login is missing, the wrapper **fails closed**: nonzero
+   exit, empty stdout, and a stderr line naming the login it wanted and the source of the
+   identity. When `tea` itself is not installed the message says so instead, since "no such
+   login" would send the reader to create a login they cannot create.
+5. With **no identity set**, the old host-default behaviour is unchanged (first login
+   configured for that host, else the API fallback).
+
+Step 4 replaced a fallback that picked any login configured for the host, which meant a
+seat with no login of its own silently acted as whichever seat had configured one. That
+satisfied the author≠reviewer gate on paper while one actor held both names.
+
+**Provisioning the logins.** `tools/fleet/seat-logins.sh` projects each seat's token from
+its secrets store into tea's config under the canonical name. tea's config is a derived
+cache of the secrets store: regenerate it with the script, never hand-edit it. Run it with
+`--seat <seat>` for one seat (all seats when omitted), dry-run by default, `--apply` to write. A hand-made
+alias holding a seat's token blocks its canonical name (tea refuses one token under two
+names); `--adopt` renames it.
+
 ### Enabling it for a clone
 
 The framework installer syncs `git-credential-mosaic` to

packages/mosaic/framework/tools/git/detect-platform.sh

@@ -180,6 +180,66 @@ raise SystemExit(1)
 PY
 }
 
+# Map a host to the instance prefix used in canonical tea login names
+# ("<instance>-<identity>"). This deliberately mirrors the _idpfx case in
+# get_gitea_token(): the two credential paths must agree on what a host is called,
+# or an agent authenticates as itself on one path and as somebody else on the other.
+gitea_instance_for_host() {
+    case "${1:-}" in
+        git.uscllc.com)      echo usc ;;
+        git.mosaicstack.dev) echo mosaicstack ;;
+        *)                   return 1 ;;
+    esac
+}
+
+# Resolve the acting git identity, same precedence as get_gitea_token() step 0.
+# Prints "<identity>\t<source>" so the caller can name the source in an error.
+resolve_git_identity() {
+    local ident src
+    ident="${MOSAIC_GIT_IDENTITY:-}"
+    src="MOSAIC_GIT_IDENTITY"
+    if [[ -z "$ident" ]]; then
+        ident="$(git config --get mosaic.gitIdentity 2>/dev/null || true)"
+        src="git config mosaic.gitIdentity"
+    fi
+    [[ -n "$ident" ]] || return 1
+    printf '%s\t%s\n' "$ident" "$src"
+}
+
+# Map a repo owner to an instance. Used only by the --repo override path, which
+# has an owner and no host. Previously lived inline in lane-brief.sh; one copy so
+# the two override callers cannot drift apart.
+gitea_instance_for_owner() {
+    local owner="${1:-}"
+    owner="${owner%%/*}"
+    case "$owner" in
+        usc|USC)            echo usc ;;
+        mosaicstack|mosaic) echo mosaicstack ;;
+        *)                  return 1 ;;
+    esac
+}
+
+# Does a login of this name exist at all? The --repo override path cannot check
+# host agreement, because it has no host.
+tea_login_exists() {
+    local login_name="$1"
+    local logins_json
+    command -v tea >/dev/null 2>&1 || return 1
+    logins_json=$(tea login list --output json 2>/dev/null) || return 1
+    TEA_LOGINS_JSON="$logins_json" python3 - "$login_name" <<'PY_INNER'
+import json, os, sys
+want = sys.argv[1]
+try:
+    logins = json.loads(os.environ.get("TEA_LOGINS_JSON", "[]"))
+except Exception:
+    raise SystemExit(1)
+for login in logins if isinstance(logins, list) else []:
+    if str(login.get("name") or login.get("Name") or "") == want:
+        raise SystemExit(0)
+raise SystemExit(1)
+PY_INNER
+}
+
 tea_login_matches_host() {
     local login_name="$1" host="$2"
     local logins_json
@@ -276,6 +336,40 @@ get_gitea_login_for_host() {
         fi
     fi
 
+    # IDENTITY LADDER (#1356). Below this point the old code took the FIRST login
+    # matching the host, which is not an identity — with 43 logins on a fleet host,
+    # ~22 match one server, so a seat with no login of its own silently acted as
+    # whichever happened to be first in ~/.config/tea/config.yml. Gate 16 depends on
+    # author != reviewer, and borrowing satisfies it mechanically while violating it
+    # in fact. The token path already refuses to borrow; this is the same refusal.
+    #
+    # Enforced ONLY when an identity is resolvable, exactly like get_gitea_token():
+    # no identity means a human at a terminal, and neither path enforces there.
+    local ident ident_src inst canon
+    if IFS=$'\t' read -r ident ident_src < <(resolve_git_identity); then
+        if inst=$(gitea_instance_for_host "$host"); then
+            canon="${inst}-${ident}"
+            if tea_login_matches_host "$canon" "$host"; then
+                echo "$canon"
+                return 0
+            fi
+            # Say which of the two it is. "No such login" when tea is simply not
+            # installed is a diagnosis of a cause that was never checked, and it
+            # sends the reader off to create a login they cannot create.
+            if ! command -v tea >/dev/null 2>&1; then
+                echo "Error: git identity '$ident' requested (via $ident_src) for host '$host', but tea is not installed," >&2
+                echo "       so no login can be resolved. Refusing to guess an identity." >&2
+                return 1
+            fi
+            echo "Error: git identity '$ident' requested (via $ident_src) for host '$host', but no tea login named '$canon' exists." >&2
+            echo "       Refusing to borrow another login. Acting as a different identity would satisfy gate 16 mechanically while violating it." >&2
+            echo "       Create it with:  ~/.config/mosaic/tools/fleet/seat-logins.sh --apply --seat $ident" >&2
+            return 1
+        fi
+        # Identity known but the host is not a Mosaic instance. Fall through: the
+        # canonical name is undefined for it, so there is nothing to enforce.
+    fi
+
     login=$(find_tea_login_for_host "$host" || true)
     if [[ -n "$login" ]]; then
         echo "$login"
@@ -351,14 +445,41 @@ raise SystemExit(1)
 PY
 }
 
+# Resolve a login for an explicit --repo override, which supplies an owner and no
+# host. Takes "owner" or "owner/repo".
+#
+# The old body fell through to get_default_tea_login(), which returns the
+# default-marked login or, failing that, the first login of ANY host — arbitrary
+# identity, chosen by config file order. That is the #1356 fail-open in its worst
+# form, because unlike the host path it does not even constrain the server.
 get_gitea_login_for_repo_override() {
-    local login
+    local owner="${1:-}"
+    local login ident ident_src inst canon
 
     if [[ -n "${GITEA_LOGIN:-}" ]]; then
         echo "$GITEA_LOGIN"
         return 0
     fi
 
+    if IFS=$'\t' read -r ident ident_src < <(resolve_git_identity); then
+        if inst=$(gitea_instance_for_owner "$owner"); then
+            canon="${inst}-${ident}"
+            if tea_login_exists "$canon"; then
+                echo "$canon"
+                return 0
+            fi
+            echo "Error: git identity '$ident' (via $ident_src) has no tea login '$canon' for owner '${owner%%/*}'." >&2
+            echo "       Create it with:  ~/.config/mosaic/tools/fleet/seat-logins.sh --apply --seat $ident" >&2
+            return 1
+        fi
+        echo "Error: git identity '$ident' (via $ident_src) is set, but owner '${owner%%/*}' maps to no known instance," >&2
+        echo "       so the login name cannot be derived. Refusing to fall back to an arbitrary login." >&2
+        echo "       Set GITEA_LOGIN to name the login explicitly." >&2
+        return 1
+    fi
+
+    # No identity: a human at a terminal. Unchanged, and the same place the token
+    # path stops enforcing.
     login=$(get_default_tea_login || true)
     if [[ -n "$login" ]]; then
         echo "$login"

packages/mosaic/framework/tools/git/issue-list.sh

@@ -99,7 +99,7 @@ case "$PLATFORM" in
         ;;
     gitea)
         if [[ -n "$REPO_OVERRIDE" ]]; then
-            GITEA_LOGIN_NAME=$(get_gitea_login_for_repo_override) || {
+            GITEA_LOGIN_NAME=$(get_gitea_login_for_repo_override "$REPO_OVERRIDE") || {
                 echo "Error: Could not resolve Gitea login for --repo override. Set GITEA_LOGIN or configure a default tea login." >&2
                 exit 1
             }

packages/mosaic/framework/tools/git/lane-brief.sh

@@ -49,11 +49,27 @@ if [[ -z "$LOGIN" ]]; then
   if [[ -n "${GITEA_LOGIN:-}" ]]; then
     LOGIN="$GITEA_LOGIN"
   else
-    case "${REPO%%/*}" in
-      usc|USC) LOGIN=usc ;;
-      mosaicstack|mosaic) LOGIN=mosaicstack ;;
-      *) LOGIN="$(get_gitea_login_for_repo_override 2>/dev/null || true)" ;;
-    esac
+    # #1356: the owner-derived map below picks a SHARED login (bare `usc` /
+    # `mosaicstack`). On a seat that is borrowing another identity, which is
+    # exactly what gate 16 forbids. So the identity ladder goes first and the
+    # map is only the no-identity fallback (a human at a terminal), which is
+    # where the token path stops enforcing too.
+    if LOGIN="$(get_gitea_login_for_repo_override "$REPO")"; then
+      :
+    elif resolve_git_identity >/dev/null 2>&1; then
+      # A git identity IS set and the ladder still could not resolve a login.
+      # The named reason is already on stderr. Falling through to the map here
+      # would hand this seat a SHARED login (bare `usc` / `mosaicstack`) — the
+      # identity-borrowing #1356 exists to stop. Fail closed instead.
+      exit 2
+    else
+      # No identity: a human at a terminal. Owner-derived map, unchanged. This
+      # is the same point at which the token path stops enforcing.
+      case "${REPO%%/*}" in
+        usc|USC) LOGIN=usc ;;
+        mosaicstack|mosaic) LOGIN=mosaicstack ;;
+      esac
+    fi
   fi
 fi
 [[ -n "$LOGIN" ]] || { echo "FATAL: could not resolve a Gitea login for $REPO (pass -L or set GITEA_LOGIN)" >&2; exit 2; }

packages/mosaic/framework/tools/git/pr-list.sh

@@ -94,7 +94,7 @@ case "$PLATFORM" in
         ;;
     gitea)
         if [[ -n "$REPO_OVERRIDE" ]]; then
-            GITEA_LOGIN_NAME=$(get_gitea_login_for_repo_override) || {
+            GITEA_LOGIN_NAME=$(get_gitea_login_for_repo_override "$REPO_OVERRIDE") || {
                 echo "Error: Could not resolve Gitea login for --repo override. Set GITEA_LOGIN or configure a default tea login." >&2
                 exit 1
             }

packages/mosaic/framework/tools/git/pr-view.sh

@@ -59,7 +59,7 @@ if [[ "$PLATFORM" == "github" ]]; then
     gh pr view "$PR_NUMBER" --repo "$REPO_INFO"
 elif [[ "$PLATFORM" == "gitea" ]]; then
     if [[ -n "$REPO_OVERRIDE" ]]; then
-        GITEA_LOGIN_NAME=$(get_gitea_login_for_repo_override) || {
+        GITEA_LOGIN_NAME=$(get_gitea_login_for_repo_override "$REPO_OVERRIDE") || {
             echo "Error: Could not resolve Gitea login for --repo override. Set GITEA_LOGIN or configure a default tea login." >&2
             exit 1
         }

packages/mosaic/framework/tools/git/test-gitea-login-resolution.sh

@@ -110,8 +110,20 @@ chmod +x "$BIN_DIR/tea" "$BIN_DIR/curl"
 
 run_in_repo() {
     (
+        # HERMETICITY, second half (#1356). The empty repo-local `mosaic.gitIdentity`
+        # above pins the git-config route into identity resolution. It does NOT pin
+        # the environment route, and MOSAIC_GIT_IDENTITY is checked FIRST — so on any
+        # provisioned seat, where the launcher exports it, this suite failed before
+        # any change: rc=1 as-is, rc=0 under `env -u MOSAIC_GIT_IDENTITY`, one
+        # variable. A suite that cannot run on a seat cannot guard this code for the
+        # agents that actually run it.
+        #
+        # Unset rather than set empty: an empty MOSAIC_GIT_IDENTITY and an absent one
+        # take different branches in resolve_git_identity(), and the case under test
+        # is "no identity at all".
         cd "$REPO_DIR"
-        PATH="$BIN_DIR:$PATH" \
+        env -u MOSAIC_GIT_IDENTITY \
+        PATH="${_SANDBOX_BIN:-$BIN_DIR}:$PATH" \
         HOME="$HOME_DIR" \
         MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
         MOSAIC_TEST_LOG="$LOG_FILE" \
@@ -307,14 +319,11 @@ SH
 chmod +x "$BIN_DIR2/tea"
 
 run_in_repo2() {
-    (
-        cd "$REPO_DIR"
-        PATH="$BIN_DIR2:$PATH" \
-        HOME="$HOME_DIR" \
-        MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
-        MOSAIC_TEST_LOG="$LOG_FILE" \
-        "$@"
-    )
+    # Same sandbox as run_in_repo, different mock tea (BIN_DIR2 defines a
+    # mosaicstack login). This MUST delegate rather than re-implement: it was a
+    # copy once, and the copy silently missed the MOSAIC_GIT_IDENTITY unset, so
+    # the suite kept failing on a seat after run_in_repo was already fixed.
+    _SANDBOX_BIN="$BIN_DIR2" run_in_repo "$@"
 }
 
 git -C "$REPO_DIR" remote set-url origin https://git.mosaicstack.dev/mosaicstack/stack.git
@@ -340,6 +349,123 @@ if [[ "$override_wins" != "mosaicstack" ]]; then
 fi
 git -C "$REPO_DIR" remote set-url origin https://git.uscllc.com/USC/uconnect.git
 
+# ---------------------------------------------------------------------------
+# #1356: the git-identity ladder. A seat declares who it is (MOSAIC_GIT_IDENTITY
+# or `git config mosaic.gitIdentity`); resolution must use THAT seat's login and
+# must REFUSE to borrow another one when it is absent. Silently borrowing
+# satisfies gate 16 mechanically (a review exists) while violating it (the
+# reviewer and the author are the same actor under two names).
+#
+# BIN_DIR3 mocks a tea that holds a canonical per-seat login, which is what a
+# projected seat looks like. BIN_DIR2 (mosaicstack only) is reused as the
+# "seat has no login" case — no third mock needed for the negative branch.
+# ---------------------------------------------------------------------------
+BIN_DIR3="$WORK_DIR/bin3"
+mkdir -p "$BIN_DIR3"
+cp "$BIN_DIR/curl" "$BIN_DIR3/curl"
+cat > "$BIN_DIR3/tea" <<'SH'
+#!/usr/bin/env bash
+set -euo pipefail
+if [[ "$*" == "login list --output json" ]]; then
+    cat <<'JSON'
+[
+  {"name":"mosaicstack","url":"https://git.mosaicstack.dev","user":"ci-bot"},
+  {"name":"mosaicstack-testseat","url":"https://git.mosaicstack.dev","user":"testseat"},
+  {"name":"usc","url":"https://git.uscllc.com","user":"ci-bot"}
+]
+JSON
+    exit 0
+fi
+printf 'tea %s\n' "$*" >> "$MOSAIC_TEST_LOG"
+exit 0
+SH
+chmod +x "$BIN_DIR3/tea"
+
+run_in_repo3() { _SANDBOX_BIN="$BIN_DIR3" run_in_repo "$@"; }
+
+git -C "$REPO_DIR" remote set-url origin https://git.mosaicstack.dev/mosaicstack/stack.git
+
+# Branch 1 (host path): identity set, canonical login PRESENT -> that login wins
+# over the shared `mosaicstack` one, which is what host-matching alone would pick.
+ladder_hit=$(run_in_repo3 env MOSAIC_GIT_IDENTITY=testseat bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_host git.mosaicstack.dev
+')
+if [[ "$ladder_hit" != "mosaicstack-testseat" ]]; then
+    echo "Expected identity ladder to select 'mosaicstack-testseat'; got '$ladder_hit'" >&2
+    exit 1
+fi
+
+# CONTROL for branch 1: the same mock, no identity, must still resolve by host.
+# Without this, branch 1 passing proves nothing about the ladder specifically --
+# it would also pass if the code just picked the last matching login.
+ladder_none=$(run_in_repo3 bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_host git.mosaicstack.dev
+')
+if [[ "$ladder_none" != "mosaicstack" ]]; then
+    echo "Expected no-identity host resolution to stay 'mosaicstack'; got '$ladder_none'" >&2
+    exit 1
+fi
+
+# Branch 2 (host path): identity set, canonical login ABSENT -> fail closed with a
+# named error. Two assertions, and they are not the same one twice: rc!=0 proves
+# it refused, and the ABSENCE of any login on stdout proves it did not borrow the
+# `mosaicstack` login that is sitting right there matching the host.
+ladder_err=$(run_in_repo2 env MOSAIC_GIT_IDENTITY=testseat bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_host git.mosaicstack.dev
+' 2>&1 1>/dev/null || true)
+ladder_out=$(run_in_repo2 env MOSAIC_GIT_IDENTITY=testseat bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_host git.mosaicstack.dev
+' 2>/dev/null || true)
+if [[ -n "$ladder_out" ]]; then
+    echo "Identity ladder BORROWED login '$ladder_out' instead of failing closed" >&2
+    exit 1
+fi
+if ! grep -q "mosaicstack-testseat" <<<"$ladder_err"; then
+    echo "Expected the error to name the login it wanted; got: $ladder_err" >&2
+    exit 1
+fi
+
+# Branch 3: `git config mosaic.gitIdentity` is the second rung and must work when
+# the environment variable is absent -- a seat may be configured either way.
+git -C "$REPO_DIR" config mosaic.gitIdentity testseat
+ladder_gitcfg=$(run_in_repo3 bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_host git.mosaicstack.dev
+')
+git -C "$REPO_DIR" config --unset mosaic.gitIdentity || true
+if [[ "$ladder_gitcfg" != "mosaicstack-testseat" ]]; then
+    echo "Expected git-config identity rung to select 'mosaicstack-testseat'; got '$ladder_gitcfg'" >&2
+    exit 1
+fi
+
+# Branch 4 (--repo override path): same rule, owner-derived instead of host-derived.
+override_ladder=$(run_in_repo3 env MOSAIC_GIT_IDENTITY=testseat bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_repo_override mosaicstack/stack
+')
+if [[ "$override_ladder" != "mosaicstack-testseat" ]]; then
+    echo "Expected --repo override ladder to select 'mosaicstack-testseat'; got '$override_ladder'" >&2
+    exit 1
+fi
+
+# Branch 5: explicit GITEA_LOGIN outranks the ladder. An operator naming a login
+# by hand is a deliberate act, not an accident to be second-guessed.
+override_explicit=$(run_in_repo3 env MOSAIC_GIT_IDENTITY=testseat GITEA_LOGIN=mosaicstack bash -c '
+    source "'"$SCRIPT_DIR"'/detect-platform.sh"
+    get_gitea_login_for_repo_override mosaicstack/stack
+')
+if [[ "$override_explicit" != "mosaicstack" ]]; then
+    echo "Expected explicit GITEA_LOGIN to outrank the identity ladder; got '$override_explicit'" >&2
+    exit 1
+fi
+
+git -C "$REPO_DIR" remote set-url origin https://git.uscllc.com/USC/uconnect.git
+
+
 # ---------------------------------------------------------------------------
 # #865 Blocker 1 & 2: get_gitea_token_for_login must resolve the SAME token as
 # PyYAML would (or fail closed identically) even when PyYAML is ABSENT, and must

packages/mosaic/framework/tools/git/test-issue-close-fail-closed.sh

@@ -76,7 +76,22 @@ exit 0
 EOF
     chmod +x "$MOCK_BIN/tea"
 }
+# #1356: login resolution is now identity-aware, so the tea-branch fixture must
+# offer the login the RUNNER's identity resolves to; otherwise every case below
+# fails closed before reaching the branch under test.
+#
+# This does NOT make the suite hermetic, and it is not trying to. The API-path
+# cases (5-7) need a usable Gitea token, and with an identity set the token path
+# reads that seat's credential file rather than the GITEA_TOKEN exported above.
+# So this suite passes only where the runner owns a real credential for its own
+# identity, and fails with no identity at all -- on this branch and on its base
+# alike. That is a pre-existing hole in the fixture, filed separately; pinning a
+# synthetic identity here would only convert it into a confident-looking green.
+_LOGIN_IDENT="${MOSAIC_GIT_IDENTITY:-}"
 LOGIN_JSON='[{"name":"git.mosaicstack.dev","url":"https://git.mosaicstack.dev"}]'
+if [[ -n "$_LOGIN_IDENT" ]]; then
+    LOGIN_JSON='[{"name":"mosaicstack-'"$_LOGIN_IDENT"'","url":"https://git.mosaicstack.dev"},{"name":"git.mosaicstack.dev","url":"https://git.mosaicstack.dev"}]'
+fi
 
 # The mocks must be the ones that run. Without this, a failed setup silently falls through
 # to the real tea/curl and the "test" mutates the real provider.

packages/mosaic/framework/tools/git/test-issue-create-body-safety.sh

@@ -10,6 +10,12 @@
 
 set -euo pipefail
 
+# HERMETICITY (#1356): this suite's subject is body quoting, not identity. An
+# ambient MOSAIC_GIT_IDENTITY (every provisioned seat exports one) would make the
+# identity ladder demand a per-seat login this fixture does not define, and the
+# suite would fail for a reason it is not testing.
+unset MOSAIC_GIT_IDENTITY
+
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-create-body-safety}"
 REPO_DIR="$WORK_DIR/repo"