diff --git a/packages/mosaic/framework/tools/git/test-gitea-login-resolution.sh b/packages/mosaic/framework/tools/git/test-gitea-login-resolution.sh
index 5a65f7fd..c619d134 100755
--- a/packages/mosaic/framework/tools/git/test-gitea-login-resolution.sh
+++ b/packages/mosaic/framework/tools/git/test-gitea-login-resolution.sh
@@ -7,14 +7,40 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/gitea-login-resolution}"
 REPO_DIR="$WORK_DIR/repo"
 BIN_DIR="$WORK_DIR/bin"
+HOME_DIR="$WORK_DIR/home"
 LOG_FILE="$WORK_DIR/calls.log"
 CREDENTIALS_FILE="$WORK_DIR/credentials.json"
 
 rm -rf "$WORK_DIR"
-mkdir -p "$REPO_DIR" "$BIN_DIR"
+mkdir -p "$REPO_DIR" "$BIN_DIR" "$HOME_DIR"
 
 git -C "$REPO_DIR" init -q
 git -C "$REPO_DIR" remote add origin https://git.uscllc.com/USC/uconnect.git
+# HERMETICITY (#1007) — TWO mechanisms with DIFFERENT jobs; do not conflate them.
+#
+# OPERATIVE: the empty repo-local `mosaic.gitIdentity` below. get_gitea_token()
+# step 0 resolves a per-agent identity from `git config --get mosaic.gitIdentity`,
+# which on a provisioned agent seat is set GLOBALLY and so leaks into this fresh
+# repo. It then reads a REAL per-slot token from $HOME and returns it WITHOUT ever
+# consulting MOSAIC_CREDENTIALS_FILE, so the fixture credentials below are silently
+# ignored. This suite is the one where the consequence is not subtle: it FAILS
+# outright on a provisioned seat (rc=1 bare, rc=0 with $HOME sandboxed, one
+# variable changed) and passes everywhere else, including CI, which has no
+# per-agent token to leak.
+#
+# CONTAINMENT: the sandboxed HOME in the four run helpers below. It only has to
+# bound a failure that the pin should already have prevented.
+#
+# NOTE FOR ANYONE AUDITING THIS SUITE: the sandboxed HOME is containment, NOT an
+# assay. Running a suite under a decoy HOME to test for this defect REMOVES the
+# trigger — ~/.gitconfig is where the global identity lives, so step 0 is skipped
+# by construction and every suite reads clean however vulnerable it is. To measure,
+# REPLICATE a seat (a decoy HOME whose .gitconfig sets mosaic.gitIdentity, with no
+# per-slot token) so step 0 reaches its fail-loud branch.
+#
+# Note the env-var route does NOT work: detect-platform.sh reads
+# "${MOSAIC_GIT_IDENTITY:-}", and `:-` treats set-but-empty identically to unset.
+git -C "$REPO_DIR" config mosaic.gitIdentity ""
 
 cat > "$CREDENTIALS_FILE" <<'JSON'
 {
@@ -86,6 +112,7 @@ run_in_repo() {
     (
         cd "$REPO_DIR"
         PATH="$BIN_DIR:$PATH" \
+        HOME="$HOME_DIR" \
         MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
         MOSAIC_TEST_LOG="$LOG_FILE" \
         "$@"
@@ -283,6 +310,7 @@ run_in_repo2() {
     (
         cd "$REPO_DIR"
         PATH="$BIN_DIR2:$PATH" \
+        HOME="$HOME_DIR" \
         MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
         MOSAIC_TEST_LOG="$LOG_FILE" \
         "$@"
@@ -343,7 +371,7 @@ write_fixture() { printf '%s' "$1" > "$FIXTURE_XDG/tea/config.yml"; }
 token_fallback() {
     (
         cd "$REPO_DIR"
-        XDG_CONFIG_HOME="$FIXTURE_XDG" PYTHONPATH="$NOYAML_DIR" bash -c '
+        HOME="$HOME_DIR" XDG_CONFIG_HOME="$FIXTURE_XDG" PYTHONPATH="$NOYAML_DIR" bash -c '
             source "'"$SCRIPT_DIR"'/detect-platform.sh"
             get_gitea_token_for_login "$1" "$2"
         ' _ "$1" "$2"
@@ -354,7 +382,7 @@ token_fallback() {
 token_pyyaml() {
     (
         cd "$REPO_DIR"
-        XDG_CONFIG_HOME="$FIXTURE_XDG" bash -c '
+        HOME="$HOME_DIR" XDG_CONFIG_HOME="$FIXTURE_XDG" bash -c '
             source "'"$SCRIPT_DIR"'/detect-platform.sh"
             get_gitea_token_for_login "$1" "$2"
         ' _ "$1" "$2"
diff --git a/packages/mosaic/framework/tools/git/test-issue-comment-readback.sh b/packages/mosaic/framework/tools/git/test-issue-comment-readback.sh
index b0178385..e8b1bb7c 100755
--- a/packages/mosaic/framework/tools/git/test-issue-comment-readback.sh
+++ b/packages/mosaic/framework/tools/git/test-issue-comment-readback.sh
@@ -61,15 +61,54 @@ STATE_FILE="$WORK_DIR/comments.json"
 # A dedicated scratch dir the wrapper is pointed at via TMPDIR, so the leak
 # check can assert every POST/GET body + metadata temp file is cleaned up.
 TMP_SCRATCH="$WORK_DIR/scratch"
+HOME_DIR="$WORK_DIR/home"
 
 cleanup() {
     rm -rf "$WORK_DIR"
 }
 trap cleanup EXIT
 
-mkdir -p "$REPO_DIR" "$BIN_DIR" "$XDG_DIR" "$TMP_SCRATCH"
+mkdir -p "$REPO_DIR" "$BIN_DIR" "$XDG_DIR" "$TMP_SCRATCH" "$HOME_DIR"
 git -C "$REPO_DIR" init -q
 git -C "$REPO_DIR" remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git
+# HERMETICITY (#1007) — TWO mechanisms with DIFFERENT jobs; do not conflate them.
+#
+# OPERATIVE: the empty repo-local `mosaic.gitIdentity` below. get_gitea_token()
+# step 0 resolves a per-agent identity from `git config --get mosaic.gitIdentity`,
+# which on a provisioned agent seat is set GLOBALLY and so leaks into this fresh
+# repo. It then reads a REAL per-slot token from $HOME and returns it WITHOUT ever
+# consulting MOSAIC_CREDENTIALS_FILE, so the fixture credential below is silently
+# ignored. The stub curl then rejects the unrecognised bearer, and this suite
+# fails at its FIRST case with `Gitea authenticated-identity read failed with
+# HTTP 401`. An empty repo-local value shadows the global one and reads back
+# empty at rc=0. Measured: without this pin the suite is RED on every seat.
+#
+# CONTAINMENT: the sandboxed HOME in run_comment(). It only has to bound a
+# failure that the pin should already have prevented.
+#
+# THIS SUITE WAS THE HARDEST OF THE FIVE TO SEE, and the reason is worth stating
+# because it generalises: run_comment() sends the wrapper's stdout AND stderr to
+# $OUTPUT_FILE, and the EXIT trap above deletes $WORK_DIR. So the 401 — the only
+# thing that says what went wrong — exists only inside a directory that is gone
+# by the time anyone looks. The suite exits 1 with ZERO bytes on stdout and
+# stderr. A suite that discards or deletes its own evidence turns any post-hoc
+# assay into a non-measurement: "nothing found" there means "no surviving
+# trace", never "clean". It was found by intercepting the identity read at its
+# SOURCE (a PATH shim over `git` logging every `mosaic.gitIdentity` read to a
+# file outside $WORK_DIR), which is deletion-proof by construction, rather than
+# by grepping for the symptom.
+#
+# NOTE FOR ANYONE AUDITING THIS SUITE: the sandboxed HOME is containment, NOT an
+# assay. Running a suite under a decoy HOME to test for this defect REMOVES the
+# trigger — ~/.gitconfig is where the global identity lives, so step 0 is skipped
+# by construction and every suite reads clean however vulnerable it is. To
+# measure, REPLICATE a seat (a decoy HOME whose .gitconfig sets
+# mosaic.gitIdentity, with no per-slot token) so step 0 reaches its fail-loud
+# branch — or intercept the read as described above.
+#
+# Note the env-var route does NOT work: detect-platform.sh reads
+# "${MOSAIC_GIT_IDENTITY:-}", and `:-` treats set-but-empty identically to unset.
+git -C "$REPO_DIR" config mosaic.gitIdentity ""
 
 ISSUE_NUMBER=7
 REPO_SLUG="mosaicstack/stack"
@@ -366,6 +405,7 @@ run_comment() {
         cd "$REPO_DIR"
         PATH="$BIN_DIR:$PATH" \
         TMPDIR="$TMP_SCRATCH" \
+        HOME="$HOME_DIR" \
         XDG_CONFIG_HOME="$XDG_DIR" \
         MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
         ISSUE_COMMENT_TEA_LOG="$TEA_LOG" \
diff --git a/packages/mosaic/framework/tools/git/test-issue-create-interactive-auth.sh b/packages/mosaic/framework/tools/git/test-issue-create-interactive-auth.sh
index 496e2c43..ecec60cb 100755
--- a/packages/mosaic/framework/tools/git/test-issue-create-interactive-auth.sh
+++ b/packages/mosaic/framework/tools/git/test-issue-create-interactive-auth.sh
@@ -7,13 +7,38 @@ SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/issue-create-interactive-auth}"
 REPO_DIR="$WORK_DIR/repo"
 BIN_DIR="$WORK_DIR/bin"
+HOME_DIR="$WORK_DIR/home"
 LOG_FILE="$WORK_DIR/calls.log"
 CREDENTIALS_FILE="$WORK_DIR/credentials.json"
 
 rm -rf "$WORK_DIR"
-mkdir -p "$REPO_DIR" "$BIN_DIR"
+mkdir -p "$REPO_DIR" "$BIN_DIR" "$HOME_DIR"
 git -C "$REPO_DIR" init -q
 git -C "$REPO_DIR" remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git
+# HERMETICITY (#1007) — TWO mechanisms with DIFFERENT jobs; do not conflate them.
+#
+# OPERATIVE: the empty repo-local `mosaic.gitIdentity` below. get_gitea_token()
+# step 0 resolves a per-agent identity from `git config --get mosaic.gitIdentity`,
+# which on a provisioned agent seat is set GLOBALLY and so leaks into this fresh
+# repo. It then reads a REAL per-slot token from $HOME and returns it WITHOUT ever
+# consulting MOSAIC_CREDENTIALS_FILE, so the fixture credential below is silently
+# ignored and the suite runs against a production credential. An empty repo-local
+# value shadows the global one and reads back empty at rc=0. Measured: this suite
+# resolves a per-slot token without it.
+#
+# CONTAINMENT: the sandboxed HOME in run_wrapper(). It only has to bound a failure
+# that the pin should already have prevented.
+#
+# NOTE FOR ANYONE AUDITING THIS SUITE: the sandboxed HOME is containment, NOT an
+# assay. Running a suite under a decoy HOME to test for this defect REMOVES the
+# trigger — ~/.gitconfig is where the global identity lives, so step 0 is skipped
+# by construction and every suite reads clean however vulnerable it is. To measure,
+# REPLICATE a seat (a decoy HOME whose .gitconfig sets mosaic.gitIdentity, with no
+# per-slot token) so step 0 reaches its fail-loud branch.
+#
+# Note the env-var route does NOT work: detect-platform.sh reads
+# "${MOSAIC_GIT_IDENTITY:-}", and `:-` treats set-but-empty identically to unset.
+git -C "$REPO_DIR" config mosaic.gitIdentity ""
 
 cat > "$CREDENTIALS_FILE" <<'JSON'
 {"gitea":{"mosaicstack":{"url":"https://git.mosaicstack.dev","token":"test-token"}}}
@@ -50,6 +75,7 @@ run_wrapper() {
   (
     cd "$REPO_DIR"
     PATH="$BIN_DIR:$PATH" \
+    HOME="$HOME_DIR" \
     MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
     MOSAIC_TEST_LOG="$LOG_FILE" \
     "$@"
diff --git a/packages/mosaic/framework/tools/git/test-pr-merge-gitea-empty-uid.sh b/packages/mosaic/framework/tools/git/test-pr-merge-gitea-empty-uid.sh
index c642b81e..62bf7e5e 100755
--- a/packages/mosaic/framework/tools/git/test-pr-merge-gitea-empty-uid.sh
+++ b/packages/mosaic/framework/tools/git/test-pr-merge-gitea-empty-uid.sh
@@ -8,6 +8,7 @@ WORK_ROOT="${AGENT_WORK_ROOT:-${HOME:-/tmp}/mosaic/agent-work}"
 SANDBOX="$WORK_ROOT/pr-merge-empty-uid-test-$$"
 MOCK_BIN="$SANDBOX/bin"
 REPO_DIR="$SANDBOX/repo"
+HOME_DIR="$SANDBOX/home"
 LOG_FILE="$SANDBOX/mock.log"
 
 cleanup() {
@@ -15,7 +16,7 @@ cleanup() {
 }
 trap cleanup EXIT
 
-mkdir -p "$MOCK_BIN" "$REPO_DIR"
+mkdir -p "$MOCK_BIN" "$REPO_DIR" "$HOME_DIR"
 : > "$LOG_FILE"
 
 cat > "$MOCK_BIN/tea" <<'EOF'
@@ -99,7 +100,48 @@ chmod +x "$MOCK_BIN/curl"
 cd "$REPO_DIR"
 git init -q
 git remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git
+# HERMETICITY (#1007) — TWO mechanisms with DIFFERENT jobs; do not conflate them.
+#
+# OPERATIVE: the empty repo-local `mosaic.gitIdentity` below. get_gitea_token()
+# step 0 resolves a per-agent identity from `git config --get mosaic.gitIdentity`,
+# which on a provisioned agent seat is set GLOBALLY and so leaks into this fresh
+# repo. Step 0 runs BEFORE the credential loader AND before the GITEA_TOKEN env
+# check, so the `GITEA_TOKEN=redacted-test-token` exported below is silently
+# overridden and a REAL per-slot token from $HOME is what flows through the
+# wrapper. Measured on a provisioned seat before this pin: all 5 mock-curl calls
+# carried the real per-slot token in argv and the fixture token was never used at
+# ALL. Three consequences specific to this suite:
+#   1. pr-merge.sh passes the token as `-H "Authorization: token $token"` and the
+#      mock curl logs full argv, so the real credential is written to $LOG_FILE
+#      on disk — transiently: the suite truncates that file between phases and
+#      the EXIT trap removes $SANDBOX, so it leaves NO post-hoc trace. That is
+#      why this suite was the hardest of the three to detect; observing it needs
+#      an instrument that captures argv while the run is live.
+#   2. Every failure path dumps $OUTPUT/$LOG_FILE to stderr through
+#      `sed 's/redacted-test-token/***REDACTED***/g'` — a redaction pattern that
+#      is the literal fixture string and therefore CANNOT match the token
+#      actually in use.
+#   3. The leak assertion at "Token leaked to pr-merge.sh output" greps for that
+#      same fixture string, so on a provisioned seat it passes vacuously: it is
+#      searching for a value the run never used.
+# An empty repo-local value shadows the global one and reads back empty at rc=0.
+#
+# CONTAINMENT: the sandboxed HOME exported below. It only has to bound a failure
+# that the pin should already have prevented.
+#
+# NOTE FOR ANYONE AUDITING THIS SUITE: the sandboxed HOME is containment, NOT an
+# assay. Running a suite under a decoy HOME to test for this defect REMOVES the
+# trigger — ~/.gitconfig is where the global identity lives, so step 0 is skipped
+# by construction and every suite reads clean however vulnerable it is. To measure,
+# REPLICATE a seat (a decoy HOME whose .gitconfig sets mosaic.gitIdentity, with no
+# per-slot token) so step 0 reaches its fail-loud branch.
+#
+# Note the env-var route does NOT work: detect-platform.sh reads
+# "${MOSAIC_GIT_IDENTITY:-}", and `:-` treats set-but-empty identically to unset.
+git -C "$REPO_DIR" config mosaic.gitIdentity ""
 
+# $SANDBOX/$HOME_DIR were derived from the real $HOME above, before this export.
+export HOME="$HOME_DIR"
 export PATH="$MOCK_BIN:$PATH"
 export PR_MERGE_TEST_LOG="$LOG_FILE"
 export GITEA_LOGIN="git.mosaicstack.dev"
diff --git a/packages/mosaic/framework/tools/git/test-pr-metadata-gitea.sh b/packages/mosaic/framework/tools/git/test-pr-metadata-gitea.sh
index 41ebefa8..f9dc856c 100755
--- a/packages/mosaic/framework/tools/git/test-pr-metadata-gitea.sh
+++ b/packages/mosaic/framework/tools/git/test-pr-metadata-gitea.sh
@@ -8,12 +8,68 @@ WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-metadata-gitea}"
 REPO_DIR="$WORK_DIR/repo"
 FIXTURE_DIR="$WORK_DIR/fixtures"
 STUB_DIR="$WORK_DIR/stubs"
+HOME_DIR="$WORK_DIR/home"
+CREDENTIALS_FILE="$WORK_DIR/credentials.json"
 
 rm -rf "$WORK_DIR"
-mkdir -p "$REPO_DIR" "$FIXTURE_DIR" "$STUB_DIR"
+mkdir -p "$REPO_DIR" "$FIXTURE_DIR" "$STUB_DIR" "$HOME_DIR"
 
 git -C "$REPO_DIR" init -q
 git -C "$REPO_DIR" remote add origin https://git.uscllc.com/USC/uconnect.git
+# HERMETICITY (#1007) — TWO mechanisms with DIFFERENT jobs; do not conflate them.
+#
+# OPERATIVE: the empty repo-local `mosaic.gitIdentity` below. get_gitea_token()
+# step 0 resolves a per-agent identity from `git config --get mosaic.gitIdentity`,
+# which on a provisioned agent seat is set GLOBALLY and so leaks into this fresh
+# repo. Step 0 runs BEFORE the credential loader AND before the GITEA_TOKEN env
+# check, so the `GITEA_TOKEN="stub-token"` set in the run helpers below is
+# silently overridden and a REAL per-slot token from $HOME is what reaches curl.
+# Measured on a provisioned seat before this pin: both stub-curl calls carried
+# the real token in argv. An empty repo-local value shadows the global one and
+# reads back empty at rc=0.
+#
+# CONTAINMENT: the sandboxed HOME in the three run helpers below. It only has to
+# bound a failure that the pin should already have prevented.
+#
+# NOTE FOR ANYONE AUDITING THIS SUITE: the sandboxed HOME is containment, NOT an
+# assay. Running a suite under a decoy HOME to test for this defect REMOVES the
+# trigger — ~/.gitconfig is where the global identity lives, so step 0 is skipped
+# by construction and every suite reads clean however vulnerable it is. To measure,
+# REPLICATE a seat (a decoy HOME whose .gitconfig sets mosaic.gitIdentity, with no
+# per-slot token) so step 0 reaches its fail-loud branch. See
+# test-gitea-token-identity.sh for the stronger `env -i HOME=…` form used where a
+# suite's whole subject IS identity resolution.
+#
+# Note the env-var route does NOT work: detect-platform.sh reads
+# "${MOSAIC_GIT_IDENTITY:-}", and `:-` treats set-but-empty identically to unset.
+git -C "$REPO_DIR" config mosaic.gitIdentity ""
+
+# The pin above removes step 0, but this suite has a SECOND, independent
+# dependency on operator state, and closing only the first would leave the suite
+# red on any hermetic environment. The `GITEA_TOKEN="stub-token"` /
+# `GITEA_URL="https://git.example.test"` pair the run helpers set is INERT: step 2
+# of get_gitea_token accepts GITEA_TOKEN only when GITEA_URL matches the remote
+# host, and this repo's origin is git.uscllc.com, so that pair can never satisfy
+# it. Before this fixture the only credential that could reach the authenticated
+# curl branch was a REAL one — from step 0 on an agent seat, or from step 1
+# reading the operator's own ~/.config/mosaic/credentials.json. That is why the
+# "curl success path" case passed: not because the stub credential worked, but
+# because a production credential was available.
+#
+# A fixture is used rather than relying on the sandboxed HOME making step 1 find
+# nothing: a test that passes because production configuration is ABSENT fails
+# the moment it is present. Step 1 now resolves deterministically to a value that
+# is a fixture on every machine.
+cat > "$CREDENTIALS_FILE" <<'JSON'
+{
+  "gitea": {
+    "usc": {
+      "url": "https://git.uscllc.com",
+      "token": "stub-token"
+    }
+  }
+}
+JSON
 
 cat > "$FIXTURE_DIR/gitea-standard.json" <<'JSON'
 {
@@ -131,6 +187,8 @@ run_curl_success_case() {
     set +e
     output=$(cd "$REPO_DIR" && \
         PATH="$STUB_DIR:$PATH" \
+        HOME="$HOME_DIR" \
+        MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
         TMPDIR="$tmpdir" \
         GITEA_TOKEN="stub-token" \
         GITEA_URL="https://git.example.test" \
@@ -170,6 +228,8 @@ run_curl_early_exit_cleanup_case() {
     set +e
     output=$(cd "$REPO_DIR" && \
         PATH="$STUB_DIR:$PATH" \
+        HOME="$HOME_DIR" \
+        MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
         TMPDIR="$tmpdir" \
         GITEA_TOKEN="stub-token" \
         GITEA_URL="https://git.example.test" \
@@ -204,7 +264,8 @@ run_curl_early_exit_cleanup_case() {
 run_case() {
     local fixture="$1" expected_number="$2" expected_head="$3"
     local output
-    output=$(cd "$REPO_DIR" && MOSAIC_GITEA_PR_METADATA_RAW_FILE="$fixture" "$SCRIPT_DIR/pr-metadata.sh" -n "$expected_number")
+    output=$(cd "$REPO_DIR" && HOME="$HOME_DIR" MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
+        MOSAIC_GITEA_PR_METADATA_RAW_FILE="$fixture" "$SCRIPT_DIR/pr-metadata.sh" -n "$expected_number")
     PR_METADATA_OUTPUT="$output" python3 - "$expected_number" "$expected_head" <<'PY'
 import json
 import os