feat(launch): per-agent harness homes + seat persona layer (MOSAIC-D-002)

With an active brain seat (MOSAIC_AGENT_NAME + seat dir under the brain
home), 'mosaic launch' now gives the runtime a per-agent home inside the
seat dir — <brainHome>/fleet/agents/<seat>/.<runtime> — instead of the
shared per-runtime ~/.config/mosaic/.<runtime>. Per-agent sessions,
settings, and auth live inside the seat (canon §2; dot-named so brain
ignore policy keeps credential material untracked).

- activeSeatDir(): resolves the seat only when a brain is active; agent
  names validated against a safe charset (path traversal rejected)
- seatPersonaOverlay(): <seat>/SOUL.md injected by value as a '## Seat
  Persona' overlay block layering persona on the root generic base
- launch record: config_home_kind (seat|runtime-shared) + agent_name
- bare launches (no MOSAIC_AGENT_NAME) and non-seat agents keep the
  shared home — no behavior change without a brain

Tests: launch.spec seat-home cases incl. unsafe-name matrix + persona
overlay hermetic tests (no host-roster dependency).

packages/mosaic/framework/fleet/README.md

@@ -12,6 +12,33 @@ The default tmux socket is `mosaic-fleet` so fleet commands do not touch the
 default tmux server. The roster is the desired-state authority; generated environment files are
 rebuildable projections, never a second source of configuration.
 
+## Brain-home split (fleet state vs framework templates)
+
+When a mosaic-brain clone is present, fleet **state** resolves from the brain
+home while framework templates and dispatch state stay in the config home
+(three-tree model, canon `docs/STRUCTURE-CANON.md` §2):
+
+| Path                                                                            | Without brain (legacy)                | With brain                     |
+| ------------------------------------------------------------------------------- | ------------------------------------- | ------------------------------ |
+| `fleet/agents/<seat>.env.*`                                                     | `~/.config/mosaic/fleet/agents/`      | `~/.mosaic/fleet/agents/`      |
+| `fleet/roles.local/` (overrides)                                                | `~/.config/mosaic/fleet/roles.local/` | `~/.mosaic/fleet/roles.local/` |
+| `fleet/profiles/` (working copies)                                              | `~/.config/mosaic/fleet/profiles/`    | `~/.mosaic/fleet/profiles/`    |
+| `fleet/roster.yaml`, `fleet/roles/` (baseline), `fleet/run/`, `fleet/services/` | `~/.config/mosaic/fleet/…`            | unchanged (config home)        |
+
+Activation (`packages/mosaic/src/fleet/brain-home.ts`, mirrored in
+`tools/fleet/start-agent-session.sh`):
+
+1. `MOSAIC_BRAIN_HOME` env var — explicit, always wins.
+2. Canonical `~/.mosaic` — adopted only when `MOSAIC_HOME` is the default
+   `~/.config/mosaic` AND `~/.mosaic/fleet/agents` exists. Custom
+   `--mosaic-home` values (tests, sandboxes, canaries) never adopt, keeping
+   them hermetic.
+3. Otherwise the config home (legacy single-tree behavior).
+
+Seat env dirs under a brain are subject to the same privacy boundary (0700
+dirs, 0600 files); `.env.generated` files are structure-valuable and tracked
+in the brain repo, hand-maintained `.env`/`.env.local` stay ignored and private.
+
 ## Examples
 
 - `examples/minimal.yaml` starts one local canary slot.

packages/mosaic/framework/tools/fleet/start-agent-session.sh

@@ -80,6 +80,26 @@ safe_path "$MOSAIC_HOME" || fail_env unsafe-path MOSAIC_HOME "$MOSAIC_HOME"
 
 FLEET_DIR="$MOSAIC_HOME/fleet"
 AGENT_ENV_DIR="$FLEET_DIR/agents"
+
+# Brain-home split (canon docs/STRUCTURE-CANON.md §2): seat launch envs live
+# under the brain home's fleet/agents when a brain is active; roster, roles
+# baseline, and runtime state (fleet/run) stay under MOSAIC_HOME.
+# Resolution mirrors packages/mosaic/src/fleet/brain-home.ts:
+#   1. MOSAIC_BRAIN_HOME env (explicit, always wins)
+#   2. ~/.mosaic — adopted only when MOSAIC_HOME is the default config home AND
+#      ~/.mosaic/fleet/agents exists
+#   3. MOSAIC_HOME (legacy single-tree)
+BRAIN_HOME="${MOSAIC_BRAIN_HOME:-}"
+if [ -z "$BRAIN_HOME" ]; then
+  BRAIN_HOME="$MOSAIC_HOME"
+  if [ "$(cd "$MOSAIC_HOME" 2>/dev/null && pwd -P)" = "$HOME/.config/mosaic" ] \
+     && [ -d "$HOME/.mosaic/fleet/agents" ]; then
+    BRAIN_HOME="$HOME/.mosaic"
+  fi
+fi
+if [ "$BRAIN_HOME" != "$MOSAIC_HOME" ]; then
+  AGENT_ENV_DIR="$BRAIN_HOME/fleet/agents"
+fi
 assert_managed_directory "$MOSAIC_HOME"
 assert_managed_directory "$FLEET_DIR"
 assert_private_directory "$AGENT_ENV_DIR"

packages/mosaic/framework/tools/fleet/test-start-agent-session.sh

@@ -167,6 +167,54 @@ if echo "$valid_args" | grep -qF 'bash -c'; then
   fail "launcher constructed a shell command payload"
 fi
 
+# ── Brain-home split (canon §2) ─────────────────────────────────────────
+# When MOSAIC_HOME is the default config home under $HOME and the host carries
+# $HOME/.mosaic/fleet/agents, seat envs resolve from the brain tree; the config
+# home still owns fleet/run (holder-owner) and remains a managed boundary.
+: > "$TMUX_CALLS"
+HOME_BRAIN="$ROOT/brain-home"
+CONFIG_HOME="$HOME_BRAIN/.config/mosaic"
+BRAIN="$HOME_BRAIN/.mosaic"
+mkdir -p "$CONFIG_HOME/fleet/run" "$BRAIN/fleet/agents" "$HOME_BRAIN/work"
+chmod 700 "$CONFIG_HOME" "$CONFIG_HOME/fleet" "$CONFIG_HOME/fleet/run" \
+  "$BRAIN/fleet/agents" "$HOME_BRAIN/work"
+printf '123e4567-e89b-12d3-a456-426614174000\n' > "$CONFIG_HOME/fleet/run/holder-owner"
+chmod 600 "$CONFIG_HOME/fleet/run/holder-owner"
+cat > "$BRAIN/fleet/agents/coder-brain.env.generated" <<EOF
+MOSAIC_AGENT_NAME=coder-brain
+MOSAIC_AGENT_CLASS=code
+MOSAIC_AGENT_RUNTIME=pi
+MOSAIC_AGENT_MODEL=openai-codex/gpt-5.6-sol
+MOSAIC_AGENT_REASONING=high
+MOSAIC_AGENT_TOOL_POLICY=code
+MOSAIC_AGENT_WORKDIR=$HOME_BRAIN/work
+MOSAIC_TMUX_SOCKET=mosaic-test
+EOF
+chmod 600 "$BRAIN/fleet/agents/coder-brain.env.generated"
+install_pane_binaries "$HOME_BRAIN"
+HOME="$HOME_BRAIN" PATH="$FAKE_BIN:$PATH" MOSAIC_TEST_TMUX_CALLS="$TMUX_CALLS" \
+  MOSAIC_TEST_PANE_PID=$$ MOSAIC_TEST_HOME="$HOME_BRAIN" \
+  MOSAIC_TEST_FLEET_OWNER=123e4567-e89b-12d3-a456-426614174000 \
+  MOSAIC_HOME="$CONFIG_HOME" "$START" coder-brain
+brain_args=$(tr '\0' '\n' < "$TMUX_CALLS")
+echo "$brain_args" | grep -qF new-session || fail "brain-home generated projection did not reach tmux"
+echo "$brain_args" | grep -qF 'coder-brain' || fail "brain-home agent env was not the launch source"
+[ -f "$BRAIN/fleet/agents/coder-brain.env.generated" ] || fail "brain generated env vanished"
+
+# Negative control: the SAME default-config-home shape but without
+# ~/.mosaic/fleet/agents — the config-home env tree is used directly (legacy).
+: > "$TMUX_CALLS"
+HOME_NOBRAIN="$ROOT/brainless-home"
+CONFIG_HOME_NOBRAIN="$HOME_NOBRAIN/.config/mosaic"
+write_generated "$CONFIG_HOME_NOBRAIN" "coder-legacy"
+install_pane_binaries "$HOME_NOBRAIN"
+HOME="$HOME_NOBRAIN" PATH="$FAKE_BIN:$PATH" MOSAIC_TEST_TMUX_CALLS="$TMUX_CALLS" \
+  MOSAIC_TEST_PANE_PID=$$ MOSAIC_TEST_HOME="$HOME_NOBRAIN" \
+  MOSAIC_TEST_FLEET_OWNER=123e4567-e89b-12d3-a456-426614174000 \
+  MOSAIC_HOME="$CONFIG_HOME_NOBRAIN" "$START" coder-legacy
+legacy_args=$(tr '\0' '\n' < "$TMUX_CALLS")
+echo "$legacy_args" | grep -qF new-session || fail "legacy single-tree launch regressed"
+
 # The pane must start through an absolute clean-environment boundary. Its
 # runtime command remains an argv vector, but no holder/session environment
 # control variable can pass through the pane command.

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

@@ -30,7 +30,7 @@ The Gitea API token is **never passed on a curl command line.** An `Authorizatio
 
 ### `--login` override
 
-Both `pr-review.sh` and `issue-comment.sh` accept an optional `--login <name>` flag that overrides the automatically detected Gitea login for that single invocation (as of #1280, `pr-create.sh`, `pr-merge.sh` and `issue-create.sh` accept it too, and it wins over `MOSAIC_GIT_IDENTITY` everywhere). The override selects **which credential the REST write, the `/user` identity lookup, and the read-back all use** — its token is resolved from the tea config for that login name (`get_gitea_token_for_login`), falling back to the repo host's credential when no login is named. The resolved login is **host- and port-bound**: the login's configured URL host **and effective port** (the scheme's default port — 80 for `http`, 443 for `https` — applies when a port is omitted, symmetrically on both sides) must match the repo remote's, so a login name shared across hosts (or an override configured for a different Gitea, including one on a different port of the same host) can never send one host's credential to another — a host or port mismatch fails closed rather than leaking a cross-host token. Resolving the acting identity and the read-back from the _same_ login that performs the write is essential: a write performed under an overridden login must be verified against that login's identity, not the host default's. Callers who need a different login than the host default should pass `--login <reviewer-login>`.
+Both `pr-review.sh` and `issue-comment.sh` accept an optional `--login <name>` flag that overrides the automatically detected Gitea login for that single invocation. The override selects **which credential the REST write, the `/user` identity lookup, and the read-back all use** — its token is resolved from the tea config for that login name (`get_gitea_token_for_login`), falling back to the repo host's credential when no login is named. The resolved login is **host- and port-bound**: the login's configured URL host **and effective port** (the scheme's default port — 80 for `http`, 443 for `https` — applies when a port is omitted, symmetrically on both sides) must match the repo remote's, so a login name shared across hosts (or an override configured for a different Gitea, including one on a different port of the same host) can never send one host's credential to another — a host or port mismatch fails closed rather than leaking a cross-host token. Resolving the acting identity and the read-back from the _same_ login that performs the write is essential: a write performed under an overridden login must be verified against that login's identity, not the host default's. Callers who need a different login than the host default should pass `--login <reviewer-login>`.
 
 As a durable successor to this mechanism, consider giving each reviewer/approver slot its own dedicated Gitea login credential, so that author≠reviewer holds at the credential level rather than relying on wrapper-level `--login` bookkeeping. This is a recommendation for future hardening, not something implemented by this flag.
 
@@ -58,36 +58,6 @@ token file present, both tools fall through to the existing shared-account path
 unchanged, so this feature is a no-op on any host that hasn't provisioned per-slot
 tokens.
 
-### Identity-first principal resolution in the wrappers (#1280)
-
-`resolve_gitea_principal()` (detect-platform.sh) gives the write wrappers —
-`pr-create.sh`, `pr-merge.sh`, `pr-review.sh`, `issue-create.sh`, `issue-comment.sh` —
-ONE precedence for choosing the acting principal:
-
-1. an explicit `--login <name>` (now accepted by all five; operator intent beats
-   environment), then
-2. the per-agent identity above (`MOSAIC_GIT_IDENTITY` env / worktree
-   `mosaic.gitIdentity`) when a per-slot token exists — the wrapper then writes via the
-   REST API with that identity's token and never consults `tea`, so the tea login list
-   cannot shadow the requested principal, then
-3. the tea login list — the LAST resort, never the first, because it enumerates
-   whatever logins the host happens to hold and knows nothing about which seat is
-   calling.
-
-A requested identity whose per-slot token is absent, or a `--login` whose token cannot
-resolve host-bound, **fails loud** (nonzero, naming the identity/login and the expected
-slot) instead of silently writing under whatever account `tea` has configured — that
-silent fallthrough is defect #1280 (reviews, comments, merges, PRs and issues filed
-under the wrong account). `pr-merge.sh --dry-run` reports the principal the merge would
-act as, resolved exactly as the real merge resolves it. ⚠ A **workstation-global**
-`mosaic.gitIdentity` shadows every seat on that host (a fresh clone with no local value
-resolves the global one) — set it per-worktree, not with `--global`.
-
-The resolver is covered by `test-gitea-principal-resolution.sh`; the happy-path
-ordering (identity arm REACHED, not sitting behind a tea failure) by
-`test-pr-create-identity-first.sh`; merge credential binding by
-`test-pr-merge-principal-resolution.sh`.
-
 ### Enabling it for a clone
 
 The framework installer syncs `git-credential-mosaic` to

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

@@ -497,32 +497,6 @@ get_gitea_url_for_host() {
     return 1
 }
 
-# Map a Gitea host to the per-agent identity-token slot PREFIX ("gitea-usc" /
-# "gitea-mosaicstack") used by identity-first principal resolution
-# (MOSAIC_GIT_IDENTITY / git config mosaic.gitIdentity; #1280). Returns 1 for
-# hosts with no per-slot scheme — callers treat that as "identity does not
-# bind here" and fall through to existing behavior, never as an error. This is
-# the single source of truth for the slot layout: get_gitea_token and
-# resolve_gitea_principal both derive their slot paths from here, so the two
-# resolutions can never disagree about where an identity's credential lives.
-gitea_identity_slot_prefix() {
-    case "$1" in
-        git.uscllc.com)      echo "gitea-usc" ;;
-        git.mosaicstack.dev) echo "gitea-mosaicstack" ;;
-        *) return 1 ;;
-    esac
-}
-
-# Resolve the per-slot token FILE PATH for an identity on a host. Prints the
-# absolute path on success; returns 1 (no output) when the host has no per-slot
-# scheme. Prints a PATH only — never a token value.
-gitea_identity_token_slot() {
-    local identity="$1" host="$2" prefix
-    [[ -n "$identity" ]] || return 1
-    prefix=$(gitea_identity_slot_prefix "$host") || return 1
-    printf '%s\n' "$HOME/.config/mosaic/secrets/gitea-tokens/${prefix}-${identity}.token"
-}
-
 # Resolve a Gitea API token for the given host.
 # Priority: Mosaic credential loader → GITEA_TOKEN env → ~/.git-credentials
 get_gitea_token() {
@@ -543,8 +517,13 @@ get_gitea_token() {
         _ident_src="git config mosaic.gitIdentity"
     fi
     if [[ -n "$_ident" ]]; then
-        local _idtok=""
-        if _idtok="$(gitea_identity_token_slot "$_ident" "$host" 2>/dev/null)"; then
+        local _idpfx=""
+        case "$host" in
+            git.uscllc.com)      _idpfx=gitea-usc ;;
+            git.mosaicstack.dev) _idpfx=gitea-mosaicstack ;;
+        esac
+        if [[ -n "$_idpfx" ]]; then
+            local _idtok="$HOME/.config/mosaic/secrets/gitea-tokens/${_idpfx}-${_ident}.token"
             if [[ -r "$_idtok" ]]; then
                 cat "$_idtok"
                 return 0
@@ -1486,81 +1465,6 @@ raise SystemExit(1)
 PY
 }
 
-# resolve_gitea_principal — identity-first acting-principal resolution shared by
-# the git wrappers (#1280). The defect this fixes: wrappers resolved their
-# acting principal from tea's login list FIRST, and that list enumerates
-# whatever logins happen to be configured on the host — it knows nothing about
-# which seat is calling — so a wrapper invoked with MOSAIC_GIT_IDENTITY=fargo
-# still wrote under whichever account tea held (mos-dt-0), and the correct
-# identity-aware code sat behind arms that only ran when the tea path failed.
-# Precedence here is the contract:
-#   1. an explicit login override ($1, the wrapper's --login) — operator intent
-#      beats environment;
-#   2. MOSAIC_GIT_IDENTITY env, else per-worktree `git config mosaic.gitIdentity`
-#      (mirroring get_gitea_token exactly, so resolver and token resolution can
-#      never disagree) — binds only on hosts with a per-slot token scheme;
-#   3. the tea login list — LAST resort, never the first.
-#
-# Prints exactly one line, three tab-separated fields (machine-readable for
-# wrapper dispatch and tests):
-#   mode        "login" | "identity" | "default"
-#   principal   login name (login) | identity name (identity) | tea login or "" (default)
-#   source      "tea-login:<name>" | "identity-slot:<path>" | "tea-default" | "host-credential"
-#
-# Fails LOUD (nonzero, empty stdout, stderr diagnostic) when an explicit
-# override cannot be honored — a refusal is a good day; silently falling
-# through to whoever tea has configured is the exact defect this resolves:
-#   - login mode: no host-bound token for that tea login. The existence check
-#     runs the same tea-config lookup tea itself uses; the token VALUE is
-#     discarded (never printed, never used).
-#   - identity mode: no per-slot token file for that identity on a recognized
-#     host — the diagnostic names the identity, its source, and the expected
-#     slot path. An identity requested on a host with NO per-slot scheme does
-#     not bind (matching get_gitea_token's containment) and falls to default.
-#
-# NEVER prints a token value — principal names and slot paths only.
-# $1 = explicit login override ("" when absent), $2 = host (default: the
-# origin remote's host).
-resolve_gitea_principal() {
-    local login_override="${1:-}" host="${2:-}" ident ident_src slot login
-    [[ -n "$host" ]] || { host=$(get_remote_host) || return 1; }
-
-    if [[ -n "$login_override" ]]; then
-        get_gitea_token_for_login "$login_override" "$host" >/dev/null || {
-            echo "Error: --login '$login_override' has no host-matched token on host '$host' (tea config lookup); refusing to fall back to any other principal (#1280 identity-first resolution)." >&2
-            return 1
-        }
-        printf 'login\t%s\ttea-login:%s\n' "$login_override" "$login_override"
-        return 0
-    fi
-
-    ident="${MOSAIC_GIT_IDENTITY:-}"
-    ident_src="MOSAIC_GIT_IDENTITY"
-    if [[ -z "$ident" ]]; then
-        ident="$(git config --get mosaic.gitIdentity 2>/dev/null || true)"
-        ident_src="git config mosaic.gitIdentity"
-    fi
-    if [[ -n "$ident" ]] && slot="$(gitea_identity_token_slot "$ident" "$host" 2>/dev/null)"; then
-        if [[ -r "$slot" ]]; then
-            printf 'identity\t%s\tidentity-slot:%s\n' "$ident" "$slot"
-            return 0
-        fi
-        echo "Error: git identity '$ident' requested (via $ident_src) for host '$host', but no per-slot token at $slot (#1280 identity-first resolution)." >&2
-        echo "       Refusing to fall back to the tea login list or shared credentials. Provision the per-slot token, or unset the identity." >&2
-        return 1
-    fi
-
-    # No override requested: tea's login list is the LAST resort. Absence is
-    # not an error here — callers fall back to the host credential, exactly as
-    # they did before this resolver existed (preserved behavior).
-    if login=$(get_gitea_login_for_host "$host" 2>/dev/null); then
-        printf 'default\t%s\ttea-default\n' "$login"
-    else
-        printf 'default\t\thost-credential\n'
-    fi
-    return 0
-}
-
 # Resolve HTTPS basic auth credentials for a Gitea host from ~/.git-credentials.
 # Prints "username:password" for direct curl -u consumption. Callers must not log it.
 get_gitea_basic_auth() {

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

@@ -76,36 +76,27 @@ fi
 detect_platform >/dev/null
 
 # Resolve and cache the Gitea REST endpoint + token for the current remote,
-# bound to a SPECIFIC acting principal ($1) selected identity-first (#1280):
-# an explicit --login wins, else MOSAIC_GIT_IDENTITY / git config
-# mosaic.gitIdentity binds the per-slot credential, else the tea login list
-# (last resort). Populates GITEA_API_ROOT (…/api/v1), GITEA_API_BASE
-# (…/api/v1/repos/<slug>), and GITEA_API_TOKEN.
+# bound to a SPECIFIC login identity ($1). Populates GITEA_API_ROOT (…/api/v1),
+# GITEA_API_BASE (…/api/v1/repos/<slug>), and GITEA_API_TOKEN.
 #
-# The token is resolved for the EFFECTIVE principal so that the single
-# credential used for the write ALSO drives the /user identity read and the
-# read-back — write token and read-back token are the same identity by
-# construction (this is the credential-ordering fix: a --login override is no
-# longer written under one credential and verified under a different default
-# one). When $2 is "identity" the principal ($1) is a requested git identity:
-# the token MUST resolve from that identity's per-slot token (get_gitea_token's
-# identity arm), failing closed rather than borrowing the tea default login —
-# the tea login list must never shadow a requested identity (#1280). When $2
-# is "explicit" the principal came from a caller-supplied --login: that exact
-# login's token MUST resolve, and we FAIL CLOSED rather than silently
-# downgrading the write to the host default identity. Otherwise the best-effort
-# default path applies (per-login token, else the host-scoped credential).
-# Returns non-zero (clear stderr) on any resolution failure.
+# The token is resolved for the EFFECTIVE login (the --login override when
+# given, otherwise the detected default) so that the single credential used for
+# the write ALSO drives the /user identity read and the read-back — write token
+# and read-back token are the same identity by construction (this is the
+# credential-ordering fix: a --login override is no longer written under one
+# credential and verified under a different default one). Falls back to the
+# host-scoped credential ONLY when NO --login override was supplied (the
+# best-effort default path). When $2 is "explicit" the login came from a
+# caller-supplied --login: that exact login's token MUST resolve, and we FAIL
+# CLOSED rather than silently downgrading the write to the host default
+# identity — otherwise a caller relying on a dedicated per-role credential would
+# be told the write succeeded as requested while it was attributed to the shared
+# default. Returns non-zero (clear stderr) on any resolution failure.
 gitea_resolve_api_for_login() {
     local effective_login="$1" override_explicit="${2:-}" host configured_url repo
 
     host=$(get_remote_host)
-    if [[ "$override_explicit" == "identity" ]]; then
-        GITEA_API_TOKEN=$(get_gitea_token "$host") || {
-            echo "Error: could not resolve the per-slot token for requested git identity '$effective_login' on host '$host'; refusing to fall back to the tea login list or shared credentials (comment write/read-back, #1280)." >&2
-            return 1
-        }
-    elif [[ -n "$override_explicit" ]]; then
+    if [[ -n "$override_explicit" ]]; then
         GITEA_API_TOKEN=$(get_gitea_token_for_login "$effective_login" "$host") || {
             echo "Error: could not resolve a host-matched Gitea token for --login '$effective_login' on host '$host'; refusing to fall back to the host default identity or a cross-host credential (comment write/read-back)" >&2
             return 1
@@ -327,31 +318,23 @@ if [[ "$PLATFORM" == "github" ]]; then
     gh issue comment "$ISSUE_NUMBER" --body "$COMMENT"
     echo "Added comment to GitHub issue #$ISSUE_NUMBER"
 elif [[ "$PLATFORM" == "gitea" ]]; then
-    # Resolve the acting principal identity-first (#1280): an explicit --login
-    # wins; otherwise MOSAIC_GIT_IDENTITY / git config mosaic.gitIdentity
-    # selects the principal when a per-slot token exists (fail-loud when it
-    # does not); the tea login list is the LAST resort — it knows nothing about
-    # which seat is calling, so resolving from it first wrote under whichever
-    # account tea had configured (the #1280 family).
-    principal_host=$(get_remote_host)
-    if ! principal_resolved="$(resolve_gitea_principal "$LOGIN_OVERRIDE" "$principal_host")"; then
-        # resolve_gitea_principal already printed the fail-loud diagnostic.
-        exit 1
-    fi
-    PRINCIPAL_MODE="$(printf '%s' "$principal_resolved" | cut -f1)"
-    PRINCIPAL_NAME="$(printf '%s' "$principal_resolved" | cut -f2)"
+    # Resolve the login this comment should be attributed to: the --login
+    # override when given, otherwise the detected default for this repo's host.
+    # A --login override always wins. Otherwise name this repo host's login only
+    # as a best effort: the login name merely selects a per-login token, and
+    # gitea_resolve_api_for_login falls back to the host credential
+    # (get_gitea_token) when no tea login is named, so the default credential
+    # still resolves even when the host tea has no matching login entry.
+    EFFECTIVE_LOGIN="$LOGIN_OVERRIDE"
+    [[ -n "$EFFECTIVE_LOGIN" ]] || EFFECTIVE_LOGIN=$(get_gitea_login 2>/dev/null || true)
 
-    # Bind the REST endpoint + token to the resolved principal, then derive the
+    # Bind the REST endpoint + token to the effective login, then derive the
     # acting identity from that SAME credential (GET /user). The write below and
     # its read-back both use this credential, so the write is verified against
-    # the identity that actually performed it.
-    if [[ "$PRINCIPAL_MODE" == "identity" ]]; then
-        gitea_resolve_api_for_login "$PRINCIPAL_NAME" identity || exit 1
-    elif [[ "$PRINCIPAL_MODE" == "login" ]]; then
-        gitea_resolve_api_for_login "$PRINCIPAL_NAME" explicit || exit 1
-    else
-        gitea_resolve_api_for_login "$PRINCIPAL_NAME" "" || exit 1
-    fi
+    # the identity that actually performed it. Passing "explicit" when --login
+    # was supplied forbids the host-default fallback: an unresolvable explicit
+    # override fails closed instead of writing under the default identity.
+    gitea_resolve_api_for_login "$EFFECTIVE_LOGIN" "${LOGIN_OVERRIDE:+explicit}" || exit 1
     ACTING_LOGIN=$(gitea_authenticated_login) || exit 1
 
     comment_id=$(gitea_create_comment_verified "$ISSUE_NUMBER" "$COMMENT" "$ACTING_LOGIN") || {

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

@@ -1,15 +1,6 @@
 #!/bin/bash
 # issue-create.sh - Create issues on Gitea or GitHub
-# Usage: issue-create.sh -t "Title" [-b "Body"] [-l "label1,label2"] [-m "milestone"] [--login <name>]
-#
-# Acting principal is resolved identity-first (#1280): an explicit --login
-# wins; otherwise MOSAIC_GIT_IDENTITY / per-worktree git config
-# mosaic.gitIdentity selects the principal when a per-slot token exists (and
-# the wrapper then creates the issue through the REST API with that identity's
-# token — tea is never invoked, so the tea login list cannot shadow the
-# requested principal); the tea login list is the LAST resort. A requested
-# identity with no per-slot token fails LOUD rather than writing under
-# whichever account tea happens to hold.
+# Usage: issue-create.sh -t "Title" [-b "Body"] [-l "label1,label2"] [-m "milestone"]
 
 set -e
 
@@ -25,14 +16,6 @@ INTERACTIVE=false
 
 # get_remote_host and get_gitea_token are provided by detect-platform.sh
 
-# Acting-principal mode set in the Gitea branch below (from
-# resolve_gitea_principal): "login" when --login was given, "identity" when a
-# git identity bound, "default" otherwise. PRINCIPAL_MODE=login makes the API
-# arm resolve the --login principal's token too, so an explicit --login keeps
-# winning even on the tea-FAILURE fallback arm.
-PRINCIPAL_MODE=""
-PRINCIPAL_NAME=""
-
 gitea_issue_create_api() {
     local host repo token url payload
     host=$(get_remote_host) || {
@@ -43,19 +26,10 @@ gitea_issue_create_api() {
         echo "Error: could not determine repo owner/name for API fallback" >&2
         return 1
     }
-    if [[ "$PRINCIPAL_MODE" == "login" ]]; then
-        token=$(get_gitea_token_for_login "$PRINCIPAL_NAME" "$host") || {
-            echo "Error: could not resolve a host-matched Gitea token for --login '$PRINCIPAL_NAME' on host '$host' (API path)" >&2
-            return 1
-        }
-    else
-        # Identity-first when MOSAIC_GIT_IDENTITY / git config mosaic.gitIdentity
-        # is set (per-slot token, fail-loud on absence); shared default otherwise.
-        token=$(get_gitea_token "$host") || {
-            echo "Error: Gitea token not found for API fallback (set GITEA_TOKEN or configure ~/.git-credentials)" >&2
-            return 1
-        }
-    fi
+    token=$(get_gitea_token "$host") || {
+        echo "Error: Gitea token not found for API fallback (set GITEA_TOKEN or configure ~/.git-credentials)" >&2
+        return 1
+    }
 
     if [[ -n "$LABELS" || -n "$MILESTONE" ]]; then
         echo "Warning: API fallback currently applies title/body only; labels/milestone require authenticated tea setup." >&2
@@ -93,7 +67,6 @@ Options:
     -b, --body BODY         Issue body/description
     -l, --labels LABELS     Comma-separated labels (e.g., "bug,feature")
     -m, --milestone NAME    Milestone name to assign
-        --login NAME        Act as this Gitea tea login (wins over MOSAIC_GIT_IDENTITY)
     -i, --interactive       Prompt for missing issue fields
     -h, --help              Show this help message
 
@@ -124,10 +97,6 @@ while [[ $# -gt 0 ]]; do
             MILESTONE="$2"
             shift 2
             ;;
-        --login)
-            LOGIN_OVERRIDE="$2"
-            shift 2
-            ;;
         -i|--interactive)
             INTERACTIVE=true
             shift
@@ -165,37 +134,13 @@ case "$PLATFORM" in
         "${CMD[@]}"
         ;;
     gitea)
-        # Resolve the acting principal identity-first (#1280). The tea login
-        # list is the LAST resort: it knows nothing about which seat is calling,
-        # and a login resolved from it first is what attributed issues to the
-        # wrong account even when MOSAIC_GIT_IDENTITY was set.
-        principal_host=$(get_remote_host 2>/dev/null || true)
-        if ! principal_resolved="$(resolve_gitea_principal "${LOGIN_OVERRIDE:-}" "$principal_host")"; then
-            # resolve_gitea_principal already printed the fail-loud diagnostic.
-            exit 1
-        fi
-        PRINCIPAL_MODE="$(printf '%s' "$principal_resolved" | cut -f1)"
-        PRINCIPAL_NAME="$(printf '%s' "$principal_resolved" | cut -f2)"
-
-        if [[ "$PRINCIPAL_MODE" == "identity" ]]; then
-            # HAPPY PATH for a requested identity: create through the REST API
-            # with the per-slot token and never invoke tea — the identity arm
-            # must be REACHED, not sit behind a tea failure (#1280).
-            gitea_issue_create_api
-            exit $?
-        fi
-
         if command -v tea >/dev/null 2>&1; then
             REPO_SLUG=$(get_repo_slug)
-            if [[ "$PRINCIPAL_MODE" == "login" ]]; then
-                GITEA_LOGIN_NAME="$PRINCIPAL_NAME"
-            else
-                GITEA_LOGIN_NAME=$(get_gitea_login) || {
-                    echo "Warning: could not resolve Gitea login for tea; trying Gitea API fallback..." >&2
-                    gitea_issue_create_api
-                    exit $?
-                }
-            fi
+            GITEA_LOGIN_NAME=$(get_gitea_login) || {
+                echo "Warning: could not resolve Gitea login for tea; trying Gitea API fallback..." >&2
+                gitea_issue_create_api
+                exit $?
+            }
             if ! get_gitea_authenticated_user "$GITEA_LOGIN_NAME" >/dev/null; then
                 echo "Warning: Tea authenticated-user validation failed (possible stale user/login); trying Gitea API fallback..." >&2
                 gitea_issue_create_api

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

@@ -1,15 +1,6 @@
 #!/bin/bash
 # pr-create.sh - Create pull requests on Gitea or GitHub
-# Usage: pr-create.sh -t "Title" [-b "Body"] [-B base] [-H head] [-l "labels"] [-m "milestone"] [--login <name>]
-#
-# Acting principal is resolved identity-first (#1280): an explicit --login
-# wins; otherwise MOSAIC_GIT_IDENTITY / per-worktree git config
-# mosaic.gitIdentity selects the principal when a per-slot token exists (and
-# the wrapper then creates the PR through the REST API with that identity's
-# token — tea is never invoked, so the tea login list cannot shadow the
-# requested principal); the tea login list is the LAST resort. A requested
-# identity with no per-slot token fails LOUD rather than writing under
-# whichever account tea happens to hold.
+# Usage: pr-create.sh -t "Title" [-b "Body"] [-B base] [-H head] [-l "labels"] [-m "milestone"]
 
 set -e
 
@@ -28,15 +19,6 @@ ISSUE=""
 
 # get_remote_host, get_gitea_token, get_repo_info, and get_gitea_repo_args are provided by detect-platform.sh
 
-# Acting-principal mode set in the Gitea branch below (from
-# resolve_gitea_principal): "login" when --login was given, "identity" when a
-# git identity bound, "default" otherwise. PRINCIPAL_MODE=login makes the API
-# arm resolve the --login principal's token too, so an explicit --login keeps
-# winning even on the tea-FAILURE fallback arm (otherwise the fallback would
-# silently re-resolve to the environment identity or shared credential).
-PRINCIPAL_MODE=""
-PRINCIPAL_NAME=""
-
 gitea_pr_create_api() {
     local host repo token url payload
     host=$(get_remote_host) || {
@@ -47,19 +29,10 @@ gitea_pr_create_api() {
         echo "Error: could not determine repo owner/name for API fallback" >&2
         return 1
     }
-    if [[ "$PRINCIPAL_MODE" == "login" ]]; then
-        token=$(get_gitea_token_for_login "$PRINCIPAL_NAME" "$host") || {
-            echo "Error: could not resolve a host-matched Gitea token for --login '$PRINCIPAL_NAME' on host '$host' (API path)" >&2
-            return 1
-        }
-    else
-        # Identity-first when MOSAIC_GIT_IDENTITY / git config mosaic.gitIdentity
-        # is set (per-slot token, fail-loud on absence); shared default otherwise.
-        token=$(get_gitea_token "$host") || {
-            echo "Error: Gitea token not found for API fallback (set GITEA_TOKEN or configure ~/.git-credentials)" >&2
-            return 1
-        }
-    fi
+    token=$(get_gitea_token "$host") || {
+        echo "Error: Gitea token not found for API fallback (set GITEA_TOKEN or configure ~/.git-credentials)" >&2
+        return 1
+    }
 
     if [[ -n "$LABELS" || -n "$MILESTONE" || "$DRAFT" == true ]]; then
         echo "Warning: API fallback applies title/body/head/base only; labels/milestone/draft require authenticated tea setup." >&2
@@ -103,7 +76,6 @@ Options:
     -H, --head BRANCH       Head branch with changes (default: current branch)
     -l, --labels LABELS     Comma-separated labels
     -m, --milestone NAME    Milestone name
-        --login NAME        Act as this Gitea tea login (wins over MOSAIC_GIT_IDENTITY)
     -i, --issue NUMBER      Link to issue (auto-generates title if not provided)
     -d, --draft             Create as draft PR
     -h, --help              Show this help message
@@ -144,10 +116,6 @@ while [[ $# -gt 0 ]]; do
             MILESTONE="$2"
             shift 2
             ;;
-        --login)
-            LOGIN_OVERRIDE="$2"
-            shift 2
-            ;;
         -i|--issue)
             ISSUE="$2"
             shift 2
@@ -206,41 +174,15 @@ case "$PLATFORM" in
         "${CMD[@]}"
         ;;
     gitea)
-        # Resolve the acting principal identity-first (#1280). The tea login
-        # list is the LAST resort: it knows nothing about which seat is calling,
-        # and a login resolved from it first is what attributed PRs to the wrong
-        # account even when MOSAIC_GIT_IDENTITY was set.
-        principal_host=$(get_remote_host 2>/dev/null || true)
-        if ! principal_resolved="$(resolve_gitea_principal "${LOGIN_OVERRIDE:-}" "$principal_host")"; then
-            # resolve_gitea_principal already printed the fail-loud diagnostic.
-            exit 1
-        fi
-        PRINCIPAL_MODE="$(printf '%s' "$principal_resolved" | cut -f1)"
-        PRINCIPAL_NAME="$(printf '%s' "$principal_resolved" | cut -f2)"
-
-        if [[ "$PRINCIPAL_MODE" == "identity" ]]; then
-            # HAPPY PATH for a requested identity: the per-slot token IS the
-            # credential, so create through the REST API directly and never
-            # invoke tea — the identity arm must be REACHED, not sit behind a
-            # tea failure (#1280). Fail-loud on a missing slot already happened
-            # in resolve_gitea_principal.
-            gitea_pr_create_api
-            exit $?
-        fi
-
         # tea pull create syntax. Always pass --repo because tea repo inference
         # is unreliable in Mosaic worktrees/profile shells. Use arrays instead
         # of eval so markdown backticks/body content are not shell-executed.
         REPO_SLUG=$(get_repo_slug)
-        if [[ "$PRINCIPAL_MODE" == "login" ]]; then
-            GITEA_LOGIN_NAME="$PRINCIPAL_NAME"
-        else
-            GITEA_LOGIN_NAME=$(get_gitea_login) || {
-                echo "Warning: could not resolve Gitea login for tea; trying Gitea API fallback..." >&2
-                gitea_pr_create_api
-                exit $?
-            }
-        fi
+        GITEA_LOGIN_NAME=$(get_gitea_login) || {
+            echo "Warning: could not resolve Gitea login for tea; trying Gitea API fallback..." >&2
+            gitea_pr_create_api
+            exit $?
+        }
         if ! get_gitea_authenticated_user "$GITEA_LOGIN_NAME" >/dev/null; then
             echo "Warning: Tea authenticated-user validation failed (possible stale user/login); trying Gitea API fallback..." >&2
             gitea_pr_create_api

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

@@ -1,13 +1,6 @@
 #!/bin/bash
 # pr-merge.sh - Merge pull requests on Gitea or GitHub
-# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d] [--expect-head SHA] [--co-author-trailers --escalate-to PRINCIPAL] [--login <name>]
-#
-# Acting principal is resolved identity-first (#1280): an explicit --login
-# wins; otherwise MOSAIC_GIT_IDENTITY / per-worktree git config
-# mosaic.gitIdentity selects the credential (per-slot token, fail-loud when
-# absent); the shared host credential is the last resort. The merge is
-# performed with the resolved credential only — never a cross-principal
-# fallback (an HTTP 401 from the identity-bound token is a hard stop).
+# Usage: pr-merge.sh -n PR_NUMBER [-m squash] [-d] [--expect-head SHA] [--co-author-trailers --escalate-to PRINCIPAL]
 
 set -euo pipefail
 
@@ -23,7 +16,6 @@ DRY_RUN=false
 EXPECT_HEAD=""
 CO_AUTHOR_TRAILERS=false
 ESCALATE_TO=""
-LOGIN_OVERRIDE=""
 
 usage() {
     cat <<EOF
@@ -39,7 +31,6 @@ Options:
         --expect-head SHA   Refuse unless the PR head matches this full commit SHA
         --co-author-trailers Build verified trailers from linked PR commit authors
         --escalate-to NAME  Named principal for an unresolved-author BLOCK
-        --login NAME        Act as this Gitea tea login (wins over MOSAIC_GIT_IDENTITY)
     -h, --help              Show this help message
 
 Examples:
@@ -48,7 +39,6 @@ Examples:
     $(basename "$0") -n 42 -d                 # Squash merge and delete branch
     $(basename "$0") -n 42 --expect-head 0123456789abcdef0123456789abcdef01234567
     $(basename "$0") -n 42 --co-author-trailers --escalate-to tl-mosaic
-    $(basename "$0") -n 42 --login fred-ms    # Merge under the fred-ms tea login
 EOF
     exit "${1:-1}"
 }
@@ -92,14 +82,6 @@ while [[ $# -gt 0 ]]; do
             ESCALATE_TO="$2"
             shift 2
             ;;
-        --login|-l)
-            if [[ $# -lt 2 ]]; then
-                echo "Error: --login requires one tea login name." >&2
-                exit 1
-            fi
-            LOGIN_OVERRIDE="$2"
-            shift 2
-            ;;
         -h|--help)
             usage 0
             ;;
@@ -590,22 +572,9 @@ PY
 merge_gitea_with_api() {
     local host="$1" token attempt_rc
 
-    # Identity-first principal resolution (#1280): an explicit --login wins
-    # over MOSAIC_GIT_IDENTITY (operator intent beats environment); otherwise
-    # get_gitea_token resolves the identity's per-slot token when an identity
-    # is requested (fail-loud when absent) and the shared host credential only
-    # when no identity is set. No cross-principal fallback: whatever resolves
-    # here is the ONLY credential the merge is attempted with.
-    if [[ -n "$LOGIN_OVERRIDE" ]]; then
-        if ! token=$(get_gitea_token_for_login "$LOGIN_OVERRIDE" "$host"); then
-            echo "Error: --login '$LOGIN_OVERRIDE' has no host-matched token on host '$host'; refusing to merge under any other principal (#1280 identity-first resolution)." >&2
-            return 1
-        fi
-    else
-        if ! token=$(get_gitea_token "$host"); then
-            echo "Error: Could not resolve the required Gitea token; refusing merge without changing principals." >&2
-            return 1
-        fi
+    if ! token=$(get_gitea_token "$host"); then
+        echo "Error: Could not resolve the required Gitea token; refusing merge without changing principals." >&2
+        return 1
     fi
     if [[ -z "$token" ]]; then
         echo "Error: Required Gitea token resolved empty; refusing merge without changing principals." >&2
@@ -633,25 +602,10 @@ if [[ "$DRY_RUN" == true ]]; then
             echo "Error: Cannot determine host from origin remote URL" >&2
             exit 1
         }
-        # Report the acting principal the merge WOULD use, resolved the same
-        # way the real merge resolves it (#1280) — a dry run that names a
-        # different principal than the merge would act as is a lie.
-        if ! principal_resolved="$(resolve_gitea_principal "$LOGIN_OVERRIDE" "$HOST")"; then
-            # Fail-loud diagnostic already printed (unresolvable --login or a
-            # requested identity with no per-slot token).
-            exit 1
-        fi
-        DRY_PRINCIPAL_MODE="$(printf '%s' "$principal_resolved" | cut -f1)"
-        DRY_PRINCIPAL_NAME="$(printf '%s' "$principal_resolved" | cut -f2)"
-        case "$DRY_PRINCIPAL_MODE" in
-            login)    DRY_PRINCIPAL_DESC="tea login '$DRY_PRINCIPAL_NAME'" ;;
-            identity) DRY_PRINCIPAL_DESC="git identity '$DRY_PRINCIPAL_NAME' (per-slot credential)" ;;
-            *)        DRY_PRINCIPAL_DESC="default host credential" ;;
-        esac
         if [[ "$CO_AUTHOR_TRAILERS" == true ]]; then
-            echo "Dry run: would verify PR commit authors and merge PR #$PR_NUMBER on $HOST as $DRY_PRINCIPAL_DESC with authenticated Gitea API message fields (base=$BASE_BRANCH, method=squash)."
+            echo "Dry run: would verify PR commit authors and merge PR #$PR_NUMBER on $HOST with authenticated Gitea API message fields (base=$BASE_BRANCH, method=squash)."
         else
-            echo "Dry run: would merge PR #$PR_NUMBER on $HOST as $DRY_PRINCIPAL_DESC with the authenticated exact-head Gitea API path (base=$BASE_BRANCH, method=squash)."
+            echo "Dry run: would merge PR #$PR_NUMBER on $HOST with the authenticated exact-head Gitea API path (base=$BASE_BRANCH, method=squash)."
         fi
     else
         echo "Dry run: would merge PR #$PR_NUMBER on $PLATFORM (base=$BASE_BRANCH, method=squash)."

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

@@ -76,7 +76,7 @@ while [[ $# -gt 0 ]]; do
             echo "  -n, --number   PR number (required)"
             echo "  -a, --action   Review action: approve, request-changes, comment (required)"
             echo "  -c, --comment  Review comment (required for request-changes)"
-            echo "  -l, --login    Override the detected Gitea tea login (all actions; wins over MOSAIC_GIT_IDENTITY)"
+            echo "  -l, --login    Override the detected Gitea tea login (approve/request-changes only)"
             echo "  -r, --repo     Explicit owner/repo slug (skips git-remote slug inference)"
             echo "  -H, --host     Explicit Gitea host (skips remote-host inference)"
             echo "  -h, --help     Show this help"
@@ -346,14 +346,7 @@ gitea_resolve_api_for_login() {
     else
         host=$(get_remote_host)
     fi
-    if [[ "$override_explicit" == "identity" ]]; then
-        # Requested git identity (#1280): the per-slot token MUST resolve via
-        # get_gitea_token's identity arm; never borrow the tea default login.
-        GITEA_API_TOKEN=$(get_gitea_token "$host") || {
-            echo "Error: could not resolve the per-slot token for requested git identity '$effective_login' on host '$host'; refusing to fall back to the tea login list or shared credentials (review write/read-back, #1280)." >&2
-            return 1
-        }
-    elif [[ -n "$override_explicit" ]]; then
+    if [[ -n "$override_explicit" ]]; then
         GITEA_API_TOKEN=$(get_gitea_token_for_login "$effective_login" "$host") || {
             echo "Error: could not resolve a host-matched Gitea token for --login '$effective_login' on host '$host'; refusing to fall back to the host default identity or a cross-host credential (review write/read-back)" >&2
             return 1
@@ -683,32 +676,29 @@ if [[ "$PLATFORM" == "github" ]]; then
             ;;
     esac
 elif [[ "$PLATFORM" == "gitea" ]]; then
-    # Resolve the acting principal ONCE for every action, identity-first
-    # (#1280): an explicit --login wins; otherwise MOSAIC_GIT_IDENTITY /
-    # per-worktree git config mosaic.gitIdentity selects the principal when a
-    # per-slot token exists (fail-loud when it does not); the tea login list is
-    # the LAST resort — it enumerates whatever logins this host happens to hold
-    # and knows nothing about which seat is calling, so resolving from it first
-    # wrote under whichever account tea had configured (the #1280 family).
-    principal_host="${HOST_OVERRIDE:-$(get_remote_host 2>/dev/null || true)}"
-    if ! principal_resolved="$(resolve_gitea_principal "$LOGIN_OVERRIDE" "$principal_host")"; then
-        # resolve_gitea_principal already printed the fail-loud diagnostic.
-        exit 1
-    fi
-    PRINCIPAL_MODE="$(printf '%s' "$principal_resolved" | cut -f1)"
-    PRINCIPAL_NAME="$(printf '%s' "$principal_resolved" | cut -f2)"
     case $ACTION in
         approve)
-            # Identity-first principal resolution (#1280): PRINCIPAL_MODE /
-            # PRINCIPAL_NAME were resolved once above from --login >
-            # MOSAIC_GIT_IDENTITY / git config > tea login list (last resort).
-            if [[ "$PRINCIPAL_MODE" == "identity" ]]; then
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" identity || exit 1
-            elif [[ "$PRINCIPAL_MODE" == "login" ]]; then
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" explicit || exit 1
-            else
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" "" || exit 1
-            fi
+            # Best-effort host for the tea-login GUESS only (gitea_resolve_api_for_login
+            # below re-derives the real host from HOST_OVERRIDE/remote independently and
+            # is authoritative). Prefer an explicit -H/--host; otherwise best-effort
+            # git-remote inference, tolerating its ABSENCE (a bare `get_remote_host` here
+            # under `set -e`, with no origin and no -H, previously killed the script
+            # SILENTLY — exit 1, zero output — even though -r/-H are exactly the flags
+            # that support running with no usable origin at all).
+            host="${HOST_OVERRIDE:-$(get_remote_host 2>/dev/null || true)}"
+            # A --login override always wins. Otherwise name this host's login
+            # only as a best effort: the login name merely selects a per-login
+            # token, and gitea_resolve_api_for_login falls back to the host
+            # credential (get_gitea_token) when no tea login is named — so a host
+            # tea's login list need not enumerate exotic (e.g. ported) hosts for
+            # the default credential to resolve. The single resolved token is
+            # then used for the write, the /user identity, and the read-back.
+            EFFECTIVE_LOGIN="$LOGIN_OVERRIDE"
+            [[ -n "$EFFECTIVE_LOGIN" ]] || EFFECTIVE_LOGIN=$(get_gitea_login_for_host "$host" 2>/dev/null || true)
+            # Bind the REST endpoint + token to the effective login, then derive
+            # the acting identity from that SAME credential so the review submit
+            # and its read-back verify against the identity that performed them.
+            gitea_resolve_api_for_login "$EFFECTIVE_LOGIN" "${LOGIN_OVERRIDE:+explicit}" || exit 1
             ACTING_LOGIN=$(gitea_authenticated_login) || exit 1
             head_sha=$(gitea_pr_head_sha "$PR_NUMBER") || exit 1
             # The review body (if any) travels with the review itself in the REST
@@ -725,16 +715,24 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
                 echo "Error: Comment required for request-changes"
                 exit 1
             fi
-            # Identity-first principal resolution (#1280): PRINCIPAL_MODE /
-            # PRINCIPAL_NAME were resolved once above from --login >
-            # MOSAIC_GIT_IDENTITY / git config > tea login list (last resort).
-            if [[ "$PRINCIPAL_MODE" == "identity" ]]; then
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" identity || exit 1
-            elif [[ "$PRINCIPAL_MODE" == "login" ]]; then
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" explicit || exit 1
-            else
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" "" || exit 1
-            fi
+            # Best-effort host for the tea-login GUESS only (gitea_resolve_api_for_login
+            # below re-derives the real host from HOST_OVERRIDE/remote independently and
+            # is authoritative). Prefer an explicit -H/--host; otherwise best-effort
+            # git-remote inference, tolerating its ABSENCE (a bare `get_remote_host` here
+            # under `set -e`, with no origin and no -H, previously killed the script
+            # SILENTLY — exit 1, zero output — even though -r/-H are exactly the flags
+            # that support running with no usable origin at all).
+            host="${HOST_OVERRIDE:-$(get_remote_host 2>/dev/null || true)}"
+            # A --login override always wins. Otherwise name this host's login
+            # only as a best effort: the login name merely selects a per-login
+            # token, and gitea_resolve_api_for_login falls back to the host
+            # credential (get_gitea_token) when no tea login is named — so a host
+            # tea's login list need not enumerate exotic (e.g. ported) hosts for
+            # the default credential to resolve. The single resolved token is
+            # then used for the write, the /user identity, and the read-back.
+            EFFECTIVE_LOGIN="$LOGIN_OVERRIDE"
+            [[ -n "$EFFECTIVE_LOGIN" ]] || EFFECTIVE_LOGIN=$(get_gitea_login_for_host "$host" 2>/dev/null || true)
+            gitea_resolve_api_for_login "$EFFECTIVE_LOGIN" "${LOGIN_OVERRIDE:+explicit}" || exit 1
             ACTING_LOGIN=$(gitea_authenticated_login) || exit 1
             head_sha=$(gitea_pr_head_sha "$PR_NUMBER") || exit 1
             review_id=$(gitea_submit_review_verified "$PR_NUMBER" "REQUEST_CHANGES" "$COMMENT" "$ACTING_LOGIN" "$head_sha") || {
@@ -748,16 +746,24 @@ elif [[ "$PLATFORM" == "gitea" ]]; then
                 echo "Error: Comment required"
                 exit 1
             fi
-            # Identity-first principal resolution (#1280): PRINCIPAL_MODE /
-            # PRINCIPAL_NAME were resolved once above from --login >
-            # MOSAIC_GIT_IDENTITY / git config > tea login list (last resort).
-            if [[ "$PRINCIPAL_MODE" == "identity" ]]; then
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" identity || exit 1
-            elif [[ "$PRINCIPAL_MODE" == "login" ]]; then
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" explicit || exit 1
-            else
-                gitea_resolve_api_for_login "$PRINCIPAL_NAME" "" || exit 1
-            fi
+            # Best-effort host for the tea-login GUESS only (gitea_resolve_api_for_login
+            # below re-derives the real host from HOST_OVERRIDE/remote independently and
+            # is authoritative). Prefer an explicit -H/--host; otherwise best-effort
+            # git-remote inference, tolerating its ABSENCE (a bare `get_remote_host` here
+            # under `set -e`, with no origin and no -H, previously killed the script
+            # SILENTLY — exit 1, zero output — even though -r/-H are exactly the flags
+            # that support running with no usable origin at all).
+            host="${HOST_OVERRIDE:-$(get_remote_host 2>/dev/null || true)}"
+            # A --login override always wins. Otherwise name this host's login
+            # only as a best effort: the login name merely selects a per-login
+            # token, and gitea_resolve_api_for_login falls back to the host
+            # credential (get_gitea_token) when no tea login is named — so a host
+            # tea's login list need not enumerate exotic (e.g. ported) hosts for
+            # the default credential to resolve. The single resolved token is
+            # then used for the write, the /user identity, and the read-back.
+            EFFECTIVE_LOGIN="$LOGIN_OVERRIDE"
+            [[ -n "$EFFECTIVE_LOGIN" ]] || EFFECTIVE_LOGIN=$(get_gitea_login_for_host "$host" 2>/dev/null || true)
+            gitea_resolve_api_for_login "$EFFECTIVE_LOGIN" "${LOGIN_OVERRIDE:+explicit}" || exit 1
             ACTING_LOGIN=$(gitea_authenticated_login) || exit 1
             comment_id=$(gitea_create_comment_verified "$PR_NUMBER" "$COMMENT" "$ACTING_LOGIN") || {
                 echo "Error: could not create and verify a comment on Gitea PR #$PR_NUMBER via a provider-returned created id (#865)." >&2

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

@@ -1,255 +0,0 @@
-#!/usr/bin/env bash
-# Regression harness for detect-platform.sh's resolve_gitea_principal() — the
-# identity-first acting-principal resolution shared by the git wrappers
-# (mosaicstack/stack #1280).
-#
-# The contract under test (precedence: --login > MOSAIC_GIT_IDENTITY /
-# git config mosaic.gitIdentity > tea login list, which is the LAST resort):
-#   1. identity env + per-slot token present -> mode=identity, principal=
-#      identity name, source names the identity's slot PATH (never a token
-#      value).
-#   2. identity env + per-slot token ABSENT -> FAIL LOUD: nonzero, empty
-#      stdout, stderr naming the identity and the expected slot path.
-#   3. identity env + --login -> --login wins (login mode resolves even when
-#      the identity has no slot — operator intent beats environment).
-#   4. identity unset + no --login -> default mode: the tea login list
-#      resolves the principal exactly as before (preserved behavior).
-#   5. no identity + no host-matching tea login -> default/host-credential
-#      (preserved behavior; absence is not an error on the default path).
-#   6. identity on an UNRECOGNIZED host (no per-slot scheme) -> does not bind;
-#      default mode (containment, mirroring get_gitea_token).
-#   7. --login with no host-bound token for that login -> FAIL LOUD, stderr
-#      naming the login and the host.
-#   8. git config mosaic.gitIdentity is honored when the env var is unset.
-#   9. The resolver NEVER emits a token value — stdout/stderr of every
-#      successful resolution must not contain the slot file's contents.
-#
-# Uses a stubbed tea binary, stubbed tea config.yml, stubbed credentials.json
-# and stubbed per-slot token files under a fake HOME. NEVER reads real secrets.
-
-set -euo pipefail
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/gitea-principal-resolution}"
-FAKE_HOME="$WORK_DIR/home"
-REPO_DIR="$WORK_DIR/repo"
-BIN_DIR="$WORK_DIR/bin"
-CREDENTIALS_FILE="$FAKE_HOME/.config/mosaic/credentials.json"
-
-rm -rf "$WORK_DIR"
-mkdir -p "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens" "$FAKE_HOME/.config/tea" "$REPO_DIR" "$BIN_DIR"
-
-git -C "$REPO_DIR" init -q
-git -C "$REPO_DIR" remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git
-
-cat > "$CREDENTIALS_FILE" <<'JSON'
-{
-  "gitea": {
-    "mosaicstack": {
-      "url": "https://git.mosaicstack.dev",
-      "token": "shared-mosaicstack-token"
-    },
-    "usc": {
-      "url": "https://git.uscllc.com",
-      "token": "shared-usc-token"
-    }
-  }
-}
-JSON
-
-# tea's own config store: the source get_gitea_token_for_login reads. Logins
-# "alice" (mosaicstack) and "bob-usc" (usc) carry sentinel token values that
-# the assertions prove are NEVER emitted by the resolver.
-cat > "$FAKE_HOME/.config/tea/config.yml" <<'YAML'
-logins:
-- name: alice
-  url: https://git.mosaicstack.dev
-  token: SECRET-alice-tea-token
-- name: bob-usc
-  url: https://git.uscllc.com
-  token: SECRET-bob-usc-tea-token
-YAML
-
-# Stubbed tea: only what login resolution needs (`login list --output json`).
-cat > "$BIN_DIR/tea" <<'SH'
-#!/usr/bin/env bash
-set -euo pipefail
-if [[ "$*" == "login list --output json" ]]; then
-    cat <<'JSON'
-[
-  {"name":"alice","url":"https://git.mosaicstack.dev","default":true},
-  {"name":"bob-usc","url":"https://git.uscllc.com"}
-]
-JSON
-    exit 0
-fi
-exit 0
-SH
-chmod +x "$BIN_DIR/tea"
-
-# Per-slot identity token with a sentinel value the assertions prove is never
-# emitted (proving "token came from the identity's slot BY PATH, not by value").
-echo -n "SECRET-agentX-slot-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentX.token"
-
-fail=0
-assert_eq() {
-  local desc="$1" expected="$2" actual="$3"
-  if [[ "$expected" != "$actual" ]]; then
-    echo "FAIL: $desc — expected '$expected', got '$actual'" >&2
-    fail=1
-  fi
-}
-assert_contains() {
-  local desc="$1" haystack="$2" needle="$3"
-  if [[ "$haystack" != *"$needle"* ]]; then
-    echo "FAIL: $desc — missing '$needle' in: $haystack" >&2
-    fail=1
-  fi
-}
-assert_not_contains() {
-  local desc="$1" haystack="$2" needle="$3"
-  if [[ "$haystack" == *"$needle"* ]]; then
-    echo "FAIL: $desc — must not contain '$needle', got: $haystack" >&2
-    fail=1
-  fi
-}
-
-# Runs resolve_gitea_principal for $1=login_override $2=host inside REPO_DIR
-# (per-worktree git config resolves there) under a fake HOME, stubbed tea, and
-# stubbed credentials. Extra env (e.g. MOSAIC_GIT_IDENTITY) via $@.
-call_resolver() {
-  local login="$1" host="$2"; shift 2
-  (
-    cd "$REPO_DIR"
-    env -i HOME="$FAKE_HOME" PATH="$BIN_DIR:$PATH" \
-      GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_SYSTEM=/dev/null \
-      MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
-      DETECT_PLATFORM_SH="$SCRIPT_DIR/detect-platform.sh" "$@" \
-      bash -c 'source "$DETECT_PLATFORM_SH"; resolve_gitea_principal "$1" "$2"' _ "$login" "$host"
-  )
-}
-
-field() { printf '%s' "$1" | cut -f"$2"; }
-
-# ---------------------------------------------------------------------------
-# 1. Identity env + slot present -> identity mode, slot named BY PATH, and no
-#    token value ever emitted.
-# ---------------------------------------------------------------------------
-git -C "$REPO_DIR" config --unset mosaic.gitIdentity 2>/dev/null || true
-out=$(call_resolver "" "git.mosaicstack.dev" MOSAIC_GIT_IDENTITY=agentX)
-assert_eq "identity mode"            "identity" "$(field "$out" 1)"
-assert_eq "identity principal"       "agentX"   "$(field "$out" 2)"
-assert_eq "identity slot source" \
-  "identity-slot:$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentX.token" \
-  "$(field "$out" 3)"
-assert_not_contains "identity stdout leaks token" "$out" "SECRET"
-
-# ---------------------------------------------------------------------------
-# 2. Identity env + slot ABSENT -> fail loud: nonzero, empty stdout, stderr
-#    naming the identity and the expected slot path.
-# ---------------------------------------------------------------------------
-stderr_file="$WORK_DIR/stderr.tmp"
-set +e
-out=$(call_resolver "" "git.mosaicstack.dev" MOSAIC_GIT_IDENTITY=agentNoSlot 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -eq 0 ]]; then
-  echo "FAIL: missing slot — expected nonzero return, got 0 (stdout='$out')" >&2
-  fail=1
-fi
-if [[ -n "$out" ]]; then
-  echo "FAIL: missing slot — expected empty stdout, got '$out'" >&2
-  fail=1
-fi
-err=$(cat "$stderr_file")
-assert_contains "missing slot names identity"  "$err" "agentNoSlot"
-assert_contains "missing slot names slot path" "$err" \
-  "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentNoSlot.token"
-assert_not_contains "missing-slot stderr leaks token" "$err" "SECRET"
-
-# ---------------------------------------------------------------------------
-# 3. Identity + --login -> --login wins. Also wins when the identity has NO
-#    slot (no identity check may veto an explicit login).
-# ---------------------------------------------------------------------------
-out=$(call_resolver "alice" "git.mosaicstack.dev" MOSAIC_GIT_IDENTITY=agentX)
-assert_eq "login beats identity (mode)"      "login" "$(field "$out" 1)"
-assert_eq "login beats identity (principal)" "alice" "$(field "$out" 2)"
-assert_eq "login source" "tea-login:alice" "$(field "$out" 3)"
-out=$(call_resolver "alice" "git.mosaicstack.dev" MOSAIC_GIT_IDENTITY=agentNoSlot)
-assert_eq "login beats slot-less identity" "login" "$(field "$out" 1)"
-
-# ---------------------------------------------------------------------------
-# 4. No identity, no --login -> default mode via the tea login list
-#    (preserved behavior).
-# ---------------------------------------------------------------------------
-out=$(call_resolver "" "git.mosaicstack.dev")
-assert_eq "default mode"          "default" "$(field "$out" 1)"
-assert_eq "default principal"     "alice"   "$(field "$out" 2)"
-assert_eq "default source"        "tea-default" "$(field "$out" 3)"
-
-# ---------------------------------------------------------------------------
-# 5. No identity, no --login, no host-matching tea login -> default with the
-#    host credential (absence is not an error on the default path).
-# ---------------------------------------------------------------------------
-out=$(call_resolver "" "git.unknown.test")
-assert_eq "no-match default mode"  "default" "$(field "$out" 1)"
-assert_eq "no-match default principal" "" "$(field "$out" 2)"
-assert_eq "no-match default source" "host-credential" "$(field "$out" 3)"
-
-# ---------------------------------------------------------------------------
-# 6. Identity on an UNRECOGNIZED host -> does not bind; default mode
-#    (containment, mirroring get_gitea_token's scope).
-# ---------------------------------------------------------------------------
-out=$(call_resolver "" "github.com" MOSAIC_GIT_IDENTITY=agentX)
-assert_eq "unrecognized host falls to default" "default" "$(field "$out" 1)"
-
-# ---------------------------------------------------------------------------
-# 7. --login with no host-bound token for that login -> fail loud, stderr
-#    naming the login and the host.
-# ---------------------------------------------------------------------------
-: > "$stderr_file"
-set +e
-out=$(call_resolver "ghost-login" "git.mosaicstack.dev" 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -eq 0 ]]; then
-  echo "FAIL: unknown --login — expected nonzero return, got 0 (stdout='$out')" >&2
-  fail=1
-fi
-err=$(cat "$stderr_file")
-assert_contains "unknown login names login" "$err" "ghost-login"
-assert_contains "unknown login names host"  "$err" "git.mosaicstack.dev"
-# A cross-host login (exists, but for usc) must ALSO fail loud for mosaicstack.
-set +e
-out=$(call_resolver "bob-usc" "git.mosaicstack.dev" 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -eq 0 ]]; then
-  echo "FAIL: cross-host --login — expected nonzero return, got 0" >&2
-  fail=1
-fi
-
-# ---------------------------------------------------------------------------
-# 8. git config mosaic.gitIdentity honored when env is unset.
-# ---------------------------------------------------------------------------
-git -C "$REPO_DIR" config mosaic.gitIdentity agentX
-out=$(call_resolver "" "git.mosaicstack.dev")
-assert_eq "git-config identity mode" "identity" "$(field "$out" 1)"
-assert_eq "git-config identity principal" "agentX" "$(field "$out" 2)"
-git -C "$REPO_DIR" config --unset mosaic.gitIdentity
-
-# ---------------------------------------------------------------------------
-# 9. Cross-host slot layout: the usc slot path is chosen for the usc host.
-# ---------------------------------------------------------------------------
-echo -n "SECRET-agentX-usc-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-usc-agentX.token"
-out=$(call_resolver "" "git.uscllc.com" MOSAIC_GIT_IDENTITY=agentX)
-assert_eq "usc identity mode" "identity" "$(field "$out" 1)"
-assert_eq "usc slot source" \
-  "identity-slot:$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-usc-agentX.token" \
-  "$(field "$out" 3)"
-
-if [[ "$fail" -eq 0 ]]; then
-  echo "resolve_gitea_principal identity-first resolution regression passed"
-fi
-
-exit "$fail"

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

@@ -77,30 +77,12 @@ exit 0
 SH
 chmod +x "$BIN_DIR/tea"
 
-# TRIPWIRE provider stub: this harness tests argv construction, so ANY curl
-# call is a failure of that contract (and, before this stub existed, a LIVE
-# write — the #1282–#1287 incident: the seat's real HOME leaked a global
-# mosaic.gitIdentity, flipping the wrapper into identity mode whose real
-# per-slot token created real issues on the forge). Fail loudly instead.
-cat > "$BIN_DIR/curl" <<'SH'
-#!/usr/bin/env bash
-echo "FAIL: body-safety harness reached a provider request — this test must never curl" >&2
-exit 99
-SH
-chmod +x "$BIN_DIR/curl"
-
-# Hermetic invocation: fake HOME (no credentials, no tea config, no token
-# slots) and GIT_CONFIG_GLOBAL severed — `git config --get mosaic.gitIdentity`
-# otherwise resolves the WORKSTATION's global identity (mos-dt-0 on the seat
-# that wrote this) and reroutes the wrapper into identity mode (#1280 family).
 (
     cd "$REPO_DIR"
-    env -i HOME="$WORK_DIR/home" PATH="$BIN_DIR:$PATH" \
-      GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_SYSTEM=/dev/null \
-      MOSAIC_TEST_RECEIVED="$RECEIVED_FILE" \
-      "$SCRIPT_DIR/issue-create.sh" -t "Body safety test" -b "$BODY"
+    PATH="$BIN_DIR:$PATH" \
+    MOSAIC_TEST_RECEIVED="$RECEIVED_FILE" \
+    "$SCRIPT_DIR/issue-create.sh" -t "Body safety test" -b "$BODY"
 ) >/dev/null
-mkdir -p "$WORK_DIR/home"
 
 # 1. No command substitution executed anywhere in the pipeline.
 if [[ -e "$SENTINEL" ]]; then

packages/mosaic/framework/tools/git/test-issue-create-interactive-auth.sh

@@ -47,31 +47,14 @@ SH
 chmod +x "$BIN_DIR/tea" "$BIN_DIR/curl"
 
 run_wrapper() {
-  # Hermetic: fake HOME (fixture credentials only, no token slots, no tea
-  # config) and GIT_CONFIG_GLOBAL severed — `git config --get
-  # mosaic.gitIdentity` otherwise resolves the WORKSTATION's global identity
-  # and reroutes the wrapper into identity mode before the tea paths this
-  # harness exercises (#1280 family; see test-issue-create-body-safety.sh).
-  # An `env …` prefix (used for MOSAIC_TEA_STALE_USER) is re-wrapped, not
-  # doubled: arguments beginning with "env" are shifted past.
-  local env_pairs=()
-  if [[ "${1:-}" == "env" ]]; then
-    shift
-    while [[ "$#" -gt 0 && "$1" == *=* ]]; do
-      env_pairs+=("$1")
-      shift
-    done
-  fi
   (
     cd "$REPO_DIR"
-    env -i HOME="$WORK_DIR/home" PATH="$BIN_DIR:$PATH" \
-      GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_SYSTEM=/dev/null \
-      MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
-      MOSAIC_TEST_LOG="$LOG_FILE" "${env_pairs[@]}" \
-      "$@"
+    PATH="$BIN_DIR:$PATH" \
+    MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" \
+    MOSAIC_TEST_LOG="$LOG_FILE" \
+    "$@"
   )
 }
-mkdir -p "$WORK_DIR/home"
 
 : > "$LOG_FILE"
 printf 'Interactive title\nInteractive body\nlabel-a,label-b\nM1\n' | run_wrapper "$SCRIPT_DIR/issue-create.sh" -i >/dev/null

packages/mosaic/framework/tools/git/test-pr-create-identity-first.sh

@@ -1,244 +0,0 @@
-#!/usr/bin/env bash
-# Load-bearing regression harness for pr-create.sh identity-first principal
-# resolution (mosaicstack/stack #1280).
-#
-# The failure this harness is written down to catch: `MOSAIC_GIT_IDENTITY=fargo
-# pr-create.sh …` produces a PR attributed to `mos-dt-0` (whichever account the
-# tea login list happens to hold). Before #1280 the identity-aware code existed
-# but sat on the API arm that only ran when the tea path FAILED — tea succeeded,
-# so the identity arm never executed, and every test that did not check ORDERING
-# passed. This harness checks ordering directly:
-#
-#   1. identity set + slot present -> the PR is created via the REST API with
-#      the identity's per-slot token (asserted by sentinel value AT the fake
-#      provider), and tea's `pr create` is NEVER invoked.
-#   2. identity set + slot ABSENT -> nonzero, stderr naming the identity and
-#      the expected slot path; neither tea `pr create` nor any API request
-#      fires. No silent fallback to the tea login list.
-#   3. identity set + --login -> --login wins: tea runs WITH the explicit
-#      --login, no API request.
-#   4. nothing set -> preserved behavior: tea path with the tea-list login.
-#
-# Uses a stubbed tea, a stubbed curl provider, stubbed credentials.json and
-# per-slot token under a fake HOME. NEVER reads real secrets or hits a live
-# forge — all assertions are against the stubs' logs.
-
-set -euo pipefail
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-create-identity-first}"
-FAKE_HOME="$WORK_DIR/home"
-REPO_DIR="$WORK_DIR/repo"
-TOOLS_DIR="$WORK_DIR/tools"
-BIN_DIR="$WORK_DIR/bin"
-LOG_FILE="$WORK_DIR/calls.log"
-CREDENTIALS_FILE="$FAKE_HOME/.config/mosaic/credentials.json"
-
-rm -rf "$WORK_DIR"
-mkdir -p "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens" "$FAKE_HOME/.config/tea" \
-  "$REPO_DIR" "$TOOLS_DIR/git" "$TOOLS_DIR/_lib" "$BIN_DIR"
-
-# Fixture: the real scripts under test, copied so sibling stubs (and the
-# ../_lib credential loader) resolve inside the fixture tree.
-cp "$SCRIPT_DIR/pr-create.sh" "$TOOLS_DIR/git/pr-create.sh"
-cp "$SCRIPT_DIR/detect-platform.sh" "$TOOLS_DIR/git/detect-platform.sh"
-cp "$SCRIPT_DIR/../_lib/credentials.sh" "$TOOLS_DIR/_lib/credentials.sh"
-chmod +x "$TOOLS_DIR/git/pr-create.sh"
-
-git -C "$REPO_DIR" init -q
-git -C "$REPO_DIR" remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git
-
-cat > "$CREDENTIALS_FILE" <<'JSON'
-{
-  "gitea": {
-    "mosaicstack": {
-      "url": "https://git.mosaicstack.dev",
-      "token": "shared-mosaicstack-token"
-    }
-  }
-}
-JSON
-
-cat > "$FAKE_HOME/.config/tea/config.yml" <<'YAML'
-logins:
-- name: alice
-  url: https://git.mosaicstack.dev
-  token: SECRET-alice-tea-token
-YAML
-
-echo -n "SECRET-agentX-slot-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentX.token"
-
-: > "$LOG_FILE"
-
-# Stubbed tea: records every invocation; `login list` feeds login resolution;
-# `api --login <n> /user` feeds get_gitea_authenticated_user; `pr create` marks
-# the marker file (its presence fails the identity-mode assertions).
-cat > "$BIN_DIR/tea" <<SH
-#!/usr/bin/env bash
-set -euo pipefail
-printf 'TEA: %s\n' "\$*" >> "$LOG_FILE"
-if [[ "\$*" == "login list --output json" ]]; then
-    cat <<'JSON'
-[
-  {"name":"alice","url":"https://git.mosaicstack.dev","default":true}
-]
-JSON
-    exit 0
-fi
-if [[ "\${1:-}" == "api" ]]; then
-    printf '%s\n' '{"login":"alice"}'
-    exit 0
-fi
-if [[ "\$*" == pr\ create* ]]; then
-    echo "TEA-PR-CREATE-INVOKED" >> "$LOG_FILE"
-    exit 0
-fi
-exit 0
-SH
-chmod +x "$BIN_DIR/tea"
-
-# Stubbed provider: records the URL and the Authorization header VALUE it
-# received, answers 201 with a created-PR object. The sentinel token values are
-# synthetic fixtures — asserting them at the provider proves WHICH slot's
-# credential carried the write.
-cat > "$BIN_DIR/curl" <<SH
-#!/usr/bin/env bash
-set -euo pipefail
-url=""
-auth=""
-while [[ \$# -gt 0 ]]; do
-    case "\$1" in
-        -H)
-            case "\$2" in
-                Authorization*) auth="\$2" ;;
-            esac
-            shift 2
-            ;;
-        *)  [[ -n "\$1" && "\$1" != -* ]] && url="\$1"
-            shift
-            ;;
-    esac
-done
-printf 'CURL-URL: %s\nCURL-AUTH: %s\n' "\$url" "\$auth" >> "$LOG_FILE"
-cat <<'JSON'
-{"number": 1299, "html_url": "https://git.mosaicstack.dev/mosaicstack/stack/pulls/1299"}
-JSON
-exit 0
-SH
-chmod +x "$BIN_DIR/curl"
-
-fail=0
-assert_contains() {
-  local desc="$1" needle="$2"
-  if ! grep -qF -- "$needle" "$LOG_FILE"; then
-    echo "FAIL: $desc — log does not contain '$needle':" >&2
-    cat "$LOG_FILE" >&2
-    fail=1
-  fi
-}
-assert_not_contains() {
-  local desc="$1" needle="$2"
-  if grep -qF -- "$needle" "$LOG_FILE"; then
-    echo "FAIL: $desc — log must not contain '$needle':" >&2
-    cat "$LOG_FILE" >&2
-    fail=1
-  fi
-}
-
-EXTRA_ARGS=""
-run_pr_create() {
-  # "$@" carries ONLY environment assignments (VAR=value); EXTRA_ARGS (if
-  # set) carries wrapper arguments, so `env` never mistakes a wrapper flag
-  # like --login for one of its own.
-  (
-    cd "$REPO_DIR"
-    # shellcheck disable=SC2086 # EXTRA_ARGS is deliberately word-split wrapper args
-    env -i HOME="$FAKE_HOME" PATH="$BIN_DIR:$PATH" \
-      GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_SYSTEM=/dev/null \
-      MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" "$@" \
-      bash "$TOOLS_DIR/git/pr-create.sh" -t "Test PR" -B next -H fix/test $EXTRA_ARGS
-  )
-}
-
-# ---------------------------------------------------------------------------
-# 1. HAPPY PATH (the load-bearing ordering test): identity set + slot present
-#    -> REST API with the per-slot token; tea `pr create` NEVER invoked.
-# ---------------------------------------------------------------------------
-set +e
-out=$(run_pr_create MOSAIC_GIT_IDENTITY=agentX 2>"$WORK_DIR/stderr-1.tmp")
-rc=$?
-set -e
-if [[ "$rc" -ne 0 ]]; then
-  echo "FAIL: identity happy path — expected rc=0, got $rc" >&2
-  cat "$WORK_DIR/stderr-1.tmp" >&2
-  fail=1
-fi
-assert_contains "identity happy path reaches the API" "CURL-URL: https://git.mosaicstack.dev/api/v1/repos/mosaicstack/stack/pulls"
-assert_contains "identity happy path carries the slot token" "CURL-AUTH: Authorization: token SECRET-agentX-slot-token"
-assert_not_contains "identity happy path must NOT invoke tea pr create" "TEA-PR-CREATE-INVOKED"
-
-# ---------------------------------------------------------------------------
-# 2. Identity set + slot ABSENT -> fail loud BEFORE any write: nonzero, stderr
-#    naming identity + slot path, no tea pr create, no API request.
-# ---------------------------------------------------------------------------
-: > "$LOG_FILE"
-set +e
-out=$(run_pr_create MOSAIC_GIT_IDENTITY=agentNoSlot 2>"$WORK_DIR/stderr-2.tmp")
-rc=$?
-set -e
-if [[ "$rc" -eq 0 ]]; then
-  echo "FAIL: missing slot — expected nonzero return, got 0 (stdout='$out')" >&2
-  fail=1
-fi
-err=$(cat "$WORK_DIR/stderr-2.tmp")
-if [[ "$err" != *"agentNoSlot"* ]]; then
-  echo "FAIL: missing slot — stderr does not name the identity:" >&2
-  echo "$err" >&2
-  fail=1
-fi
-if [[ "$err" != *"$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentNoSlot.token"* ]]; then
-  echo "FAIL: missing slot — stderr does not name the expected slot path:" >&2
-  echo "$err" >&2
-  fail=1
-fi
-assert_not_contains "missing slot must not reach tea pr create" "TEA-PR-CREATE-INVOKED"
-assert_not_contains "missing slot must not reach the API" "CURL-URL"
-
-# ---------------------------------------------------------------------------
-# 3. Identity set + --login -> --login wins: tea runs WITH the explicit login.
-# ---------------------------------------------------------------------------
-: > "$LOG_FILE"
-EXTRA_ARGS="--login alice"
-set +e
-out=$(run_pr_create MOSAIC_GIT_IDENTITY=agentX 2>"$WORK_DIR/stderr-3.tmp")
-rc=$?
-set -e
-EXTRA_ARGS=""
-if [[ "$rc" -ne 0 ]]; then
-  echo "FAIL: login override — expected rc=0, got $rc" >&2
-  cat "$WORK_DIR/stderr-3.tmp" >&2
-  fail=1
-fi
-assert_contains "login override drives tea with the explicit login" "TEA: pr create --repo mosaicstack/stack --login alice"
-assert_not_contains "login override must not hit the API" "CURL-URL"
-
-# ---------------------------------------------------------------------------
-# 4. Nothing set -> preserved behavior: tea path with the tea-list login.
-# ---------------------------------------------------------------------------
-: > "$LOG_FILE"
-set +e
-out=$(run_pr_create 2>"$WORK_DIR/stderr-4.tmp")
-rc=$?
-set -e
-if [[ "$rc" -ne 0 ]]; then
-  echo "FAIL: default path — expected rc=0, got $rc" >&2
-  cat "$WORK_DIR/stderr-4.tmp" >&2
-  fail=1
-fi
-assert_contains "default path still uses the tea-list login" "TEA: pr create --repo mosaicstack/stack --login alice"
-
-if [[ "$fail" -eq 0 ]]; then
-  echo "pr-create identity-first happy-path regression passed"
-fi
-
-exit "$fail"

packages/mosaic/framework/tools/git/test-pr-merge-principal-resolution.sh

@@ -1,247 +0,0 @@
-#!/usr/bin/env bash
-# Regression harness for pr-merge.sh identity-first principal resolution
-# (mosaicstack/stack #1280).
-#
-# Covers:
-#   1. --dry-run reports the acting principal the merge WOULD use, resolved the
-#      same way the real merge resolves it: --login > MOSAIC_GIT_IDENTITY /
-#      git config mosaic.gitIdentity > shared host credential. (The pre-#1280
-#      deployed copy reported a tea login that the merge would not act as.)
-#   2. --dry-run fails closed when the requested principal has no credential:
-#      unknown --login, or an identity with no per-slot token (stderr names
-#      the login / the identity and its slot path).
-#   3. The real merge POST carries the resolved principal's credential and no
-#      other: --login merges with that login's tea-config token; an identity
-#      merges with the per-slot token; an unresolvable --login never reaches
-#      the provider.
-#
-# Fixture pattern from test-pr-merge-head-pin.sh: the scripts under test are
-# copied into a fixture tree with stubbed pr-metadata.sh / ci-queue-wait.sh
-# siblings; the provider is a stubbed curl that records the credential it
-# received. NEVER reads real secrets or hits a live forge.
-
-set -euo pipefail
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/pr-merge-principal-resolution}"
-FAKE_HOME="$WORK_DIR/home"
-REPO_DIR="$WORK_DIR/repo"
-TOOLS_DIR="$WORK_DIR/tools"
-BIN_DIR="$WORK_DIR/bin"
-LOG_FILE="$WORK_DIR/calls.log"
-CREDENTIALS_FILE="$FAKE_HOME/.config/mosaic/credentials.json"
-SHA=0123456789abcdef0123456789abcdef01234567
-
-rm -rf "$WORK_DIR"
-mkdir -p "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens" "$FAKE_HOME/.config/tea" \
-  "$REPO_DIR" "$TOOLS_DIR/git" "$TOOLS_DIR/_lib" "$BIN_DIR"
-
-cp "$SCRIPT_DIR/pr-merge.sh" "$TOOLS_DIR/git/pr-merge.sh"
-cp "$SCRIPT_DIR/detect-platform.sh" "$TOOLS_DIR/git/detect-platform.sh"
-cp "$SCRIPT_DIR/../_lib/credentials.sh" "$TOOLS_DIR/_lib/credentials.sh"
-chmod +x "$TOOLS_DIR/git/pr-merge.sh"
-
-git -C "$REPO_DIR" init -q
-git -C "$REPO_DIR" remote add origin https://git.mosaicstack.dev/mosaicstack/stack.git
-
-# Stubbed siblings pr-merge.sh resolves relative to its own SCRIPT_DIR.
-cat > "$TOOLS_DIR/git/pr-metadata.sh" <<SH
-#!/usr/bin/env bash
-printf '%s\n' '{"baseRefName":"next","headRefName":"fix/pinned","headRefOid":"$SHA","headRepository":"mosaicstack/stack","title":"Test PR","author":{"login":"contributor"}}'
-SH
-cat > "$TOOLS_DIR/git/ci-queue-wait.sh" <<'SH'
-#!/usr/bin/env bash
-exit 0
-SH
-chmod +x "$TOOLS_DIR/git/pr-metadata.sh" "$TOOLS_DIR/git/ci-queue-wait.sh"
-
-cat > "$CREDENTIALS_FILE" <<'JSON'
-{
-  "gitea": {
-    "mosaicstack": {
-      "url": "https://git.mosaicstack.dev",
-      "token": "shared-mosaicstack-token"
-    }
-  }
-}
-JSON
-
-cat > "$FAKE_HOME/.config/tea/config.yml" <<'YAML'
-logins:
-- name: fred-ms
-  url: https://git.mosaicstack.dev
-  token: SECRET-fred-ms-tea-token
-YAML
-
-echo -n "SECRET-agentX-slot-token" > "$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentX.token"
-
-: > "$LOG_FILE"
-
-# Stubbed tea for login-list resolution only.
-cat > "$BIN_DIR/tea" <<'SH'
-#!/usr/bin/env bash
-set -euo pipefail
-if [[ "$*" == "login list --output json" ]]; then
-    cat <<'JSON'
-[
-  {"name":"fred-ms","url":"https://git.mosaicstack.dev","default":true}
-]
-JSON
-    exit 0
-fi
-exit 0
-SH
-chmod +x "$BIN_DIR/tea"
-
-# Stubbed provider. pr-merge passes curl config on STDIN with -K -; the stub
-# reads stdin, records the Authorization header it received, answers 200.
-cat > "$BIN_DIR/curl" <<SH
-#!/usr/bin/env bash
-set -euo pipefail
-url=""
-out_file=""
-stdin_config=""
-if [[ ! -t 0 ]]; then
-    stdin_config="\$(cat || true)"
-fi
-while [[ \$# -gt 0 ]]; do
-    case "\$1" in
-        -o) out_file="\$2"; shift 2 ;;
-        -K|-w|--max-filesize|--max-time|--connect-timeout|-sS) shift 2 ;;
-        *)  [[ -n "\$1" && "\$1" != -* && -z "\$url" ]] && url="\$1"
-            shift
-            ;;
-    esac
-done
-auth="\$(printf '%s' "\$stdin_config" | grep -o 'Authorization: token [^"]*' || true)"
-printf 'CURL-URL: %s\nCURL-AUTH: %s\n' "\$url" "\$auth" >> "$LOG_FILE"
-[[ -n "\$out_file" ]] && printf '{}' > "\$out_file"
-printf '200\n'
-exit 0
-SH
-chmod +x "$BIN_DIR/curl"
-
-fail=0
-assert_contains_log() {
-  local desc="$1" needle="$2"
-  if ! grep -qF -- "$needle" "$LOG_FILE"; then
-    echo "FAIL: $desc — log does not contain '$needle':" >&2
-    cat "$LOG_FILE" >&2
-    fail=1
-  fi
-}
-assert_not_contains_log() {
-  local desc="$1" needle="$2"
-  if grep -qF -- "$needle" "$LOG_FILE"; then
-    echo "FAIL: $desc — log must not contain '$needle':" >&2
-    cat "$LOG_FILE" >&2
-    fail=1
-  fi
-}
-
-run_pr_merge() {
-  local extra_args="$1"; shift
-  (
-    cd "$REPO_DIR"
-    # shellcheck disable=SC2086 # extra_args is deliberately word-split wrapper args
-    env -i HOME="$FAKE_HOME" PATH="$BIN_DIR:$PATH" \
-      GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_SYSTEM=/dev/null \
-      MOSAIC_CREDENTIALS_FILE="$CREDENTIALS_FILE" "$@" \
-      bash "$TOOLS_DIR/git/pr-merge.sh" -n 42 $extra_args
-  )
-}
-
-# ---------------------------------------------------------------------------
-# 1. --dry-run reports the resolved acting principal truthfully.
-# ---------------------------------------------------------------------------
-out=$(run_pr_merge "--dry-run" MOSAIC_GIT_IDENTITY=agentX)
-if [[ "$out" != *"as git identity 'agentX' (per-slot credential)"* ]]; then
-  echo "FAIL: dry-run identity — principal not reported: $out" >&2
-  fail=1
-fi
-
-out=$(run_pr_merge "--dry-run --login fred-ms" MOSAIC_GIT_IDENTITY=agentX)
-if [[ "$out" != *"as tea login 'fred-ms'"* ]]; then
-  echo "FAIL: dry-run login override — login not reported (must beat env identity): $out" >&2
-  fail=1
-fi
-
-out=$(run_pr_merge "--dry-run")
-if [[ "$out" != *"as default host credential"* ]]; then
-  echo "FAIL: dry-run default — not reported: $out" >&2
-  fail=1
-fi
-
-# ---------------------------------------------------------------------------
-# 2. --dry-run fails closed when the requested principal has no credential.
-# ---------------------------------------------------------------------------
-stderr_file="$WORK_DIR/stderr.tmp"
-set +e
-out=$(run_pr_merge "--dry-run --login ghost" 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -eq 0 ]] || [[ "$(cat "$stderr_file")" != *"ghost"* ]]; then
-  echo "FAIL: dry-run unknown --login — expected fail-loud naming 'ghost', rc=$rc" >&2
-  cat "$stderr_file" >&2
-  fail=1
-fi
-
-: > "$stderr_file"
-set +e
-out=$(run_pr_merge "--dry-run" MOSAIC_GIT_IDENTITY=agentNoSlot 2>"$stderr_file")
-rc=$?
-set -e
-err=$(cat "$stderr_file")
-if [[ "$rc" -eq 0 ]] || [[ "$err" != *"agentNoSlot"* ]] \
-  || [[ "$err" != *"$FAKE_HOME/.config/mosaic/secrets/gitea-tokens/gitea-mosaicstack-agentNoSlot.token"* ]]; then
-  echo "FAIL: dry-run identity without slot — expected fail-loud naming identity + slot path, rc=$rc" >&2
-  echo "$err" >&2
-  fail=1
-fi
-
-# ---------------------------------------------------------------------------
-# 3. The real merge POST carries the resolved principal's credential ONLY.
-# ---------------------------------------------------------------------------
-: > "$LOG_FILE"
-set +e
-out=$(run_pr_merge "--login fred-ms" MOSAIC_GIT_IDENTITY=agentX 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -ne 0 ]]; then
-  echo "FAIL: merge with --login — expected rc=0, got $rc" >&2
-  cat "$stderr_file" >&2
-  fail=1
-fi
-assert_contains_log "merge --login uses the login token" "CURL-AUTH: Authorization: token SECRET-fred-ms-tea-token"
-assert_not_contains_log "merge --login must not use the identity slot token" "SECRET-agentX-slot-token"
-assert_not_contains_log "merge --login must not use the shared token" "shared-mosaicstack-token"
-
-: > "$LOG_FILE"
-set +e
-out=$(run_pr_merge "" MOSAIC_GIT_IDENTITY=agentX 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -ne 0 ]]; then
-  echo "FAIL: merge with identity — expected rc=0, got $rc" >&2
-  cat "$stderr_file" >&2
-  fail=1
-fi
-assert_contains_log "merge identity uses the per-slot token" "CURL-AUTH: Authorization: token SECRET-agentX-slot-token"
-assert_not_contains_log "merge identity must not use the shared token" "shared-mosaicstack-token"
-
-: > "$LOG_FILE"
-set +e
-out=$(run_pr_merge "--login ghost" 2>"$stderr_file")
-rc=$?
-set -e
-if [[ "$rc" -eq 0 ]]; then
-  echo "FAIL: merge with unknown --login — expected nonzero, got 0" >&2
-  fail=1
-fi
-assert_not_contains_log "merge with unknown --login must not reach the provider" "CURL-URL"
-
-if [[ "$fail" -eq 0 ]]; then
-  echo "pr-merge identity-first principal resolution regression passed"
-fi
-
-exit "$fail"

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 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/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-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.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-pr-merge-queue-branch.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-gitea-principal-resolution.sh && bash framework/tools/git/test-pr-create-identity-first.sh && bash framework/tools/git/test-pr-merge-principal-resolution.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"
+    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.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/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-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.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-pr-merge-queue-branch.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/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"
   },
   "dependencies": {
     "@mosaicstack/brain": "workspace:*",

packages/mosaic/src/commands/fleet-agent-crud-command.ts

@@ -1,5 +1,6 @@
 import { readFile } from 'node:fs/promises';
 import { join, resolve } from 'node:path';
+import { fleetAgentEnvDir, fleetRolesLocalDir } from '../fleet/brain-home.js';
 import type { Command } from 'commander';
 import {
   executeFleetAgentMutation,
@@ -149,9 +150,9 @@ async function executeCommand(
     request,
     mosaicHome,
     rosterPath,
-    agentEnvDir: join(mosaicHome, 'fleet', 'agents'),
+    agentEnvDir: fleetAgentEnvDir(mosaicHome),
     rolesDir: join(mosaicHome, 'fleet', 'roles'),
-    overrideDir: join(mosaicHome, 'fleet', 'roles.local'),
+    overrideDir: fleetRolesLocalDir(mosaicHome),
     dryRun: forceDryRun || opts.dryRun === true,
     ...(deps.projectionApplier === undefined ? {} : { projectionApplier: deps.projectionApplier }),
   });

packages/mosaic/src/commands/fleet-migration-command.ts

@@ -1,5 +1,6 @@
 import { readFile } from 'node:fs/promises';
 import { join } from 'node:path';
+import { fleetAgentEnvDir, fleetRolesLocalDir } from '../fleet/brain-home.js';
 import type { Command } from 'commander';
 import {
   parseV1MigrationObservations,
@@ -120,11 +121,11 @@ export function registerFleetMigrationCommand(
           observations,
           personaDirs: {
             rolesDir: deps.rolesDir ?? join(mosaicHome, 'fleet', 'roles'),
-            overrideDir: deps.overrideDir ?? join(mosaicHome, 'fleet', 'roles.local'),
+            overrideDir: deps.overrideDir ?? fleetRolesLocalDir(mosaicHome),
           },
           environment: {
             mosaicHome,
-            agentEnvDir: join(mosaicHome, 'fleet', 'agents'),
+            agentEnvDir: fleetAgentEnvDir(mosaicHome),
           },
         });
         printJson(preview);

packages/mosaic/src/commands/fleet-personas.ts

@@ -30,19 +30,21 @@ import { lstat, readFile, readdir, stat } from 'node:fs/promises';
 import { homedir } from 'node:os';
 import { basename, isAbsolute, join, sep } from 'node:path';
 import type { Command } from 'commander';
+import { fleetRolesLocalDir } from '../fleet/brain-home.js';
 
 function defaultMosaicHome(): string {
   return process.env['MOSAIC_HOME'] ?? join(homedir(), '.config', 'mosaic');
 }
 
-/** Baseline persona role contracts (reseeded on update). */
+/** Baseline persona role contracts (reseeded on update; config home — framework). */
 export function defaultRolesDir(mosaicHome = defaultMosaicHome()): string {
   return join(mosaicHome, 'fleet', 'roles');
 }
 
-/** PRESERVE-protected override layer (survives update; wins on merge). */
+/** PRESERVE-protected override layer (survives update; wins on merge).
+ * Brain home (`~/.mosaic/fleet/roles.local`) when a brain is active. */
 export function defaultOverrideDir(mosaicHome = defaultMosaicHome()): string {
-  return join(mosaicHome, 'fleet', 'roles.local');
+  return fleetRolesLocalDir(mosaicHome);
 }
 
 /**

packages/mosaic/src/commands/fleet-profiles.ts

@@ -25,6 +25,7 @@ import { homedir } from 'node:os';
 import { basename, join } from 'node:path';
 import type { Command } from 'commander';
 import YAML from 'yaml';
+import { fleetProfilesDir } from '../fleet/brain-home.js';
 import {
   defaultOverrideDir,
   extractClassesFromDir,
@@ -36,9 +37,10 @@ function defaultMosaicHome(): string {
   return process.env['MOSAIC_HOME'] ?? join(homedir(), '.config', 'mosaic');
 }
 
-/** Directory holding the seeded profile yaml files. */
+/** Directory holding the seeded profile yaml files — brain home when active
+ * (user working copies, committed), else the config home seed. */
 export function defaultProfilesDir(mosaicHome = defaultMosaicHome()): string {
-  return join(mosaicHome, 'fleet', 'profiles');
+  return fleetProfilesDir(mosaicHome);
 }
 
 /** Directory holding the persona role contracts. */

packages/mosaic/src/commands/fleet-regen-command.ts

@@ -3,6 +3,7 @@ import { homedir } from 'node:os';
 import { join, relative, resolve } from 'node:path';
 import type { Command } from 'commander';
 import type { CommandRunner } from './fleet.js';
+import { fleetAgentEnvDir } from '../fleet/brain-home.js';
 import {
   applyPreparedGeneratedAgentEnvironmentProjection,
   prepareGeneratedAgentEnvironmentProjection,
@@ -153,7 +154,7 @@ export async function executeFleetRegen(
   options: FleetRegenOptions,
 ): Promise<FleetRegenResult> {
   const mosaicHome = defaultMosaicHome(deps);
-  const agentEnvDir = join(mosaicHome, 'fleet', 'agents');
+  const agentEnvDir = fleetAgentEnvDir(mosaicHome);
   const rosterPath = join(mosaicHome, 'fleet', 'roster.yaml');
   const readRoster = deps.readRoster ?? defaultReadRoster(deps, mosaicHome);
   const prepare = deps.prepareProjection ?? prepareGeneratedAgentEnvironmentProjection;

packages/mosaic/src/commands/fleet.ts

@@ -13,6 +13,7 @@ import {
 import { randomUUID } from 'node:crypto';
 import { homedir, hostname, userInfo } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
+import { fleetAgentEnvDir } from '../fleet/brain-home.js';
 import { fileURLToPath } from 'node:url';
 import { spawn } from 'node:child_process';
 import * as readline from 'node:readline';
@@ -158,7 +159,7 @@ export function resolveFleetPaths(mosaicHome = defaultMosaicHome()): FleetPaths
     fleetToolsDir: join(mosaicHome, 'tools', 'fleet'),
     tmuxToolsDir: join(mosaicHome, 'tools', 'tmux'),
     systemdUserDir: join(homedir(), '.config', 'systemd', 'user'),
-    agentEnvDir: join(mosaicHome, 'fleet', 'agents'),
+    agentEnvDir: fleetAgentEnvDir(mosaicHome),
   };
 }
 

packages/mosaic/src/commands/launch.spec.ts

@@ -349,3 +349,90 @@ describe('registerRuntimeLaunchers — claudex (EXPERIMENTAL overlay)', () => {
     expect(mockExit).not.toHaveBeenCalled();
   });
 });
+
+// ─── Seat harness homes (MOSAIC-D-002, brain-home split) ────────────────────
+
+import { activeSeatDir, seatPersonaOverlay } from './launch.js';
+
+describe('activeSeatDir — per-agent harness home resolution', () => {
+  let root: string;
+  const savedAgentName = process.env['MOSAIC_AGENT_NAME'];
+  const savedBrainHome = process.env['MOSAIC_BRAIN_HOME'];
+
+  beforeEach(() => {
+    root = mkdtempSync(join(tmpdir(), 'mosaic-seat-home-'));
+    delete process.env['MOSAIC_BRAIN_HOME'];
+  });
+
+  afterEach(() => {
+    rmSync(root, { recursive: true, force: true });
+    if (savedAgentName === undefined) {
+      delete process.env['MOSAIC_AGENT_NAME'];
+    } else {
+      process.env['MOSAIC_AGENT_NAME'] = savedAgentName;
+    }
+    if (savedBrainHome !== undefined) {
+      process.env['MOSAIC_BRAIN_HOME'] = savedBrainHome;
+    } else {
+      delete process.env['MOSAIC_BRAIN_HOME'];
+    }
+  });
+
+  it('resolves the seat dir when MOSAIC_BRAIN_HOME carries the seat', () => {
+    const seat = join(root, 'brain', 'fleet', 'agents', 'coder0');
+    mkdirSync(seat, { recursive: true });
+    process.env['MOSAIC_AGENT_NAME'] = 'coder0';
+    process.env['MOSAIC_BRAIN_HOME'] = join(root, 'brain');
+
+    expect(activeSeatDir(join(root, 'config', 'mosaic'))).toBe(seat);
+  });
+
+  it('returns undefined without an agent name (bare launches stay shared)', () => {
+    delete process.env['MOSAIC_AGENT_NAME'];
+    expect(activeSeatDir(join(root, 'config', 'mosaic'))).toBeUndefined();
+  });
+
+  it('returns undefined when the seat dir does not exist in the brain', () => {
+    process.env['MOSAIC_AGENT_NAME'] = 'ghost';
+    process.env['MOSAIC_BRAIN_HOME'] = join(root, 'brain');
+    mkdirSync(join(root, 'brain', 'fleet', 'agents'), { recursive: true });
+
+    expect(activeSeatDir(join(root, 'config', 'mosaic'))).toBeUndefined();
+  });
+
+  it.each(['../escape', 'a/b', '.hidden-start', '', 'spaced name'])(
+    'rejects unsafe agent name %j (path traversal cannot leave the seat store)',
+    (name: string) => {
+      process.env['MOSAIC_AGENT_NAME'] = name;
+      process.env['MOSAIC_BRAIN_HOME'] = join(root, 'brain');
+
+      expect(activeSeatDir(join(root, 'config', 'mosaic'))).toBeUndefined();
+    },
+  );
+
+  it('seatPersonaOverlay renders the seat SOUL.md as an overlay block', () => {
+    const seat = join(root, 'brain', 'fleet', 'agents', 'coder0');
+    mkdirSync(seat, { recursive: true });
+    writeFileSync(join(seat, 'SOUL.md'), '# coder0 — code seat persona\n\nShips tested code.\n');
+    process.env['MOSAIC_AGENT_NAME'] = 'coder0';
+    process.env['MOSAIC_BRAIN_HOME'] = join(root, 'brain');
+
+    const overlay = seatPersonaOverlay(join(root, 'config', 'mosaic'));
+    expect(overlay).toContain('## Seat Persona');
+    expect(overlay).toContain('coder0 — code seat persona');
+  });
+
+  it('seatPersonaOverlay is empty when the seat carries no SOUL.md', () => {
+    const seat = join(root, 'brain', 'fleet', 'agents', 'coder0');
+    mkdirSync(seat, { recursive: true });
+    process.env['MOSAIC_AGENT_NAME'] = 'coder0';
+    process.env['MOSAIC_BRAIN_HOME'] = join(root, 'brain');
+
+    expect(seatPersonaOverlay(join(root, 'config', 'mosaic'))).toBe('');
+  });
+
+  it('seatPersonaOverlay is empty when no agent name is set', () => {
+    delete process.env['MOSAIC_AGENT_NAME'];
+    expect(seatPersonaOverlay(join(root, 'config', 'mosaic'))).toBe('');
+  });
+});

packages/mosaic/src/commands/launch.ts

@@ -19,7 +19,7 @@ import {
 import { createHash, randomBytes } from 'node:crypto';
 import { createRequire } from 'node:module';
 import { homedir, hostname } from 'node:os';
-import { join, dirname } from 'node:path';
+import { join, dirname, resolve } from 'node:path';
 import type { Command } from 'commander';
 import {
   buildResolvedFleetCommsBlock,
@@ -29,6 +29,7 @@ import {
 import { readRegularFileSecure } from '../fleet/secure-file.js';
 import { readPersonaContractBlock } from '../fleet/persona-contract.js';
 import { canonicalizeRoleClass } from './fleet-personas.js';
+import { resolveBrainHome } from '../fleet/brain-home.js';
 import { launchClaudex, type ClaudexHarnessAdapter } from './claudex.js';
 import { runLeaseEnforcementDoctorCheck } from './lease-doctor-check.js';
 
@@ -64,9 +65,46 @@ const HARNESS_HOME_ENV: Record<RuntimeName, string> = {
   opencode: 'XDG_CONFIG_HOME',
 };
 
-/** Dedicated mosaic-owned home for a runtime: ~/.config/mosaic/.<runtime> */
-function harnessHome(runtime: RuntimeName): string {
-  return join(MOSAIC_HOME, `.${runtime}`);
+/** Dedicated mosaic-owned home for a runtime: ~/.config/mosaic/.<runtime>.
+ * With an active brain seat (MOSAIC_AGENT_NAME + seat dir in the brain home)
+ * the home is per-agent instead: <brainHome>/fleet/agents/<seat>/.<runtime> —
+ * per-agent sessions, settings, and auth inside the seat dir (canon §2,
+ * MOSAIC-D-002). Seat runtime dirs are dot-named so the brain's ignore policy
+ * (per-seat .pi/.claude/.codex dirs) keeps credential material untracked. */
+const SEAT_AGENT_NAME_RE = /^[a-zA-Z0-9][a-zA-Z0-9._-]*$/;
+
+export function activeSeatDir(mosaicHome: string = MOSAIC_HOME): string | undefined {
+  const agent = process.env['MOSAIC_AGENT_NAME']?.trim();
+  if (
+    agent === undefined ||
+    agent === '' ||
+    !SEAT_AGENT_NAME_RE.test(agent) ||
+    agent.includes('..')
+  ) {
+    return undefined;
+  }
+  const brain = resolveBrainHome(mosaicHome);
+  if (resolve(brain) === resolve(mosaicHome)) return undefined; // no brain
+  const seat = join(brain, 'fleet', 'agents', agent);
+  return existsSync(seat) ? seat : undefined;
+}
+
+function harnessHome(runtime: RuntimeName, mosaicHome: string = MOSAIC_HOME): string {
+  const seat = activeSeatDir(mosaicHome);
+  if (seat !== undefined) return join(seat, `.${runtime}`);
+  return join(mosaicHome, `.${runtime}`);
+}
+
+/** Seat persona block: with an active brain seat, <seat>/SOUL.md layers
+ * persona on the root generic base (canon invariant; MOSAIC-D-002). The base
+ * SOUL stays load-on-demand — only the seat delta is injected by value.
+ * Empty string when no seat is active or the seat carries no SOUL.md. */
+export function seatPersonaOverlay(mosaicHome: string = MOSAIC_HOME): string {
+  const seatDir = activeSeatDir(mosaicHome);
+  if (seatDir === undefined) return '';
+  const seatSoul = readOptional(join(seatDir, 'SOUL.md'));
+  if (!seatSoul.trim()) return '';
+  return '## Seat Persona\n\n' + seatSoul.trim();
 }
 
 /**
@@ -182,6 +220,8 @@ function recordLaunch(runtime: RuntimeName, cliArgs: string[], yolo: boolean): v
       cli_version: CLI_VERSION,
       config_home: harnessHome(runtime),
       config_home_isolated: true,
+      config_home_kind: activeSeatDir() !== undefined ? 'seat' : 'runtime-shared',
+      agent_name: process.env['MOSAIC_AGENT_NAME']?.trim() || null,
       config_home_env: HARNESS_HOME_ENV[runtime] ?? null,
       argv: redactArgv(cliArgs),
       normative_fragments: normativeFragmentDigests(runtime),
@@ -569,6 +609,11 @@ For required push/merge/issue-close/release actions, execute without routine con
   if (soulLocal.trim()) {
     overlayBlocks.push('## Persona Overlay (SOUL.local.md)\n\n' + soulLocal.trim());
   }
+  // Seat persona (MOSAIC-D-002): per-seat SOUL.md layers on the generic base.
+  const seatPersona = seatPersonaOverlay(mosaicHome);
+  if (seatPersona !== '') {
+    overlayBlocks.push(seatPersona);
+  }
   const standardsLocal = readOptional(join(mosaicHome, 'STANDARDS.local.md'));
   if (standardsLocal.trim()) {
     overlayBlocks.push('## Standards Overlay (STANDARDS.local.md)\n\n' + standardsLocal.trim());

packages/mosaic/src/fleet/brain-home.spec.ts

@@ -0,0 +1,114 @@
+import { mkdir, mkdtemp, rm } from 'node:fs/promises';
+import { homedir, tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import {
+  brainHomeIsActive,
+  fleetAgentEnvDir,
+  fleetProfilesDir,
+  fleetRolesLocalDir,
+  fleetStateDir,
+  resolveBrainHome,
+  type BrainHomeOptions,
+} from './brain-home.js';
+
+describe('fleet brain-home resolution', (): void => {
+  let cleanup: string | undefined;
+
+  const savedBrainEnv = process.env['MOSAIC_BRAIN_HOME'];
+
+  beforeEach((): void => {
+    delete process.env['MOSAIC_BRAIN_HOME'];
+  });
+
+  afterEach(async (): Promise<void> => {
+    if (savedBrainEnv === undefined) {
+      delete process.env['MOSAIC_BRAIN_HOME'];
+    } else {
+      process.env['MOSAIC_BRAIN_HOME'] = savedBrainEnv;
+    }
+    if (cleanup !== undefined) {
+      await rm(cleanup, { recursive: true, force: true });
+      cleanup = undefined;
+    }
+  });
+
+  async function makeTmp(): Promise<string> {
+    const root = await mkdtemp(join(tmpdir(), 'mosaic-brain-home-'));
+    cleanup = root;
+    return root;
+  }
+
+  it('MOSAIC_BRAIN_HOME env wins over every other signal', (): void => {
+    process.env['MOSAIC_BRAIN_HOME'] = '/explicit/brain';
+    expect(resolveBrainHome('/any/mosaic-home')).toBe('/explicit/brain');
+    expect(fleetAgentEnvDir('/any/mosaic-home')).toBe('/explicit/brain/fleet/agents');
+    expect(brainHomeIsActive('/any/mosaic-home')).toBe(true);
+  });
+
+  it('injected envBrainHome wins identically (test seam)', (): void => {
+    const opts: BrainHomeOptions = { envBrainHome: '/injected/brain' };
+    expect(resolveBrainHome('/any/mosaic-home', opts)).toBe('/injected/brain');
+    expect(fleetAgentEnvDir('/any/mosaic-home', opts)).toBe('/injected/brain/fleet/agents');
+  });
+
+  it('a non-default mosaicHome never adopts the canonical brain (hermetic legacy)', (): void => {
+    const mosaicHome = '/tmp/not-the-default-config-home';
+    expect(resolveBrainHome(mosaicHome)).toBe(mosaicHome);
+    expect(brainHomeIsActive(mosaicHome)).toBe(false);
+    expect(fleetAgentEnvDir(mosaicHome)).toBe(join(mosaicHome, 'fleet', 'agents'));
+  });
+
+  it('the default config home adopts the brain when it carries fleet/agents', async (): Promise<void> => {
+    const root = await makeTmp();
+    const brain = join(root, 'brain');
+    await mkdir(join(brain, 'fleet', 'agents'), { recursive: true });
+    const configHome = join(root, 'config', 'mosaic');
+    const opts: BrainHomeOptions = { homes: { brain, configDefault: configHome } };
+
+    expect(resolveBrainHome(configHome, opts)).toBe(brain);
+    expect(fleetAgentEnvDir(configHome, opts)).toBe(join(brain, 'fleet', 'agents'));
+    expect(fleetRolesLocalDir(configHome, opts)).toBe(join(brain, 'fleet', 'roles.local'));
+    expect(fleetProfilesDir(configHome, opts)).toBe(join(brain, 'fleet', 'profiles'));
+    expect(fleetStateDir(configHome, opts)).toBe(join(brain, 'fleet'));
+    expect(brainHomeIsActive(configHome, opts)).toBe(true);
+  });
+
+  it('the default config home stays legacy when no brain exists', async (): Promise<void> => {
+    const root = await makeTmp();
+    const configHome = join(root, 'config', 'mosaic');
+    const opts: BrainHomeOptions = {
+      homes: { brain: join(root, 'brain'), configDefault: configHome },
+    };
+
+    expect(resolveBrainHome(configHome, opts)).toBe(configHome);
+    expect(brainHomeIsActive(configHome, opts)).toBe(false);
+  });
+
+  it('an empty MOSAIC_BRAIN_HOME is ignored, not treated as set', (): void => {
+    process.env['MOSAIC_BRAIN_HOME'] = '   ';
+    expect(resolveBrainHome('/tmp/legacy-home')).toBe('/tmp/legacy-home');
+  });
+
+  it('adoption requires fleet/agents specifically, not any brain content', async (): Promise<void> => {
+    const root = await makeTmp();
+    const brain = join(root, 'brain');
+    await mkdir(join(brain, 'fleet'), { recursive: true }); // fleet without agents
+    const configHome = join(root, 'config', 'mosaic');
+    const opts: BrainHomeOptions = { homes: { brain, configDefault: configHome } };
+
+    expect(resolveBrainHome(configHome, opts)).toBe(configHome);
+  });
+
+  it('real-home control: a host brain is adopted only through the default home', (): void => {
+    // Control on the un-injected path: this host carries ~/.mosaic/fleet/agents,
+    // so the default config home resolves to the brain or legacy — both valid
+    // canonical endpoints — while a non-default home never adopts.
+    const defaultHome = join(homedir(), '.config', 'mosaic');
+    const resolved = resolveBrainHome(defaultHome);
+    expect([defaultHome, join(homedir(), '.mosaic')]).toContain(resolved);
+    expect(resolveBrainHome(join(homedir(), 'elsewhere', 'mosaic'))).toBe(
+      join(homedir(), 'elsewhere', 'mosaic'),
+    );
+  });
+});

packages/mosaic/src/fleet/brain-home.ts

@@ -0,0 +1,76 @@
+import { existsSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join, resolve } from 'node:path';
+
+/**
+ * Overridable resolution inputs (tests inject tmp homes; production reads
+ * the environment and the real home directory).
+ */
+export interface BrainHomeOptions {
+  /** Explicit brain home; defaults to `MOSAIC_BRAIN_HOME`. */
+  readonly envBrainHome?: string;
+  /**
+   * Canonical homes used for adoption. Defaults derive from the real
+   * `homedir()`: `{ brain: ~/.mosaic, configDefault: ~/.config/mosaic }`.
+   */
+  readonly homes?: { readonly brain: string; readonly configDefault: string };
+}
+
+/**
+ * Brain-home resolution — the three-tree fleet split (stack canon
+ * `docs/STRUCTURE-CANON.md` §2, first carried by the USC estate brain):
+ *
+ *   config home (~/.config/mosaic)  framework templates + dispatch state:
+ *                                   fleet/roles (baseline), fleet/roster.yaml,
+ *                                   fleet/run (heartbeats), fleet/services
+ *   brain home  (~/.mosaic)         user-owned fleet state, committed:
+ *                                   fleet/agents/<seat>.env.*, fleet/roles.local,
+ *                                   fleet/profiles working copies
+ *
+ * Resolution order:
+ *   1. `MOSAIC_BRAIN_HOME` env (explicit, always wins)
+ *   2. canonical `~/.mosaic` — adopted ONLY when mosaicHome is the real
+ *      default config home AND `~/.mosaic/fleet/agents` exists. Custom
+ *      `--mosaic-home` values (tests, sandboxes, canaries) never trigger
+ *      adoption, keeping them hermetic and deterministic.
+ *   3. mosaicHome itself (legacy single-tree behavior).
+ */
+export function resolveBrainHome(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  const explicit = options.envBrainHome ?? process.env['MOSAIC_BRAIN_HOME'];
+  if (explicit !== undefined && explicit.trim() !== '') {
+    return explicit;
+  }
+  const homes = options.homes ?? {
+    brain: join(homedir(), '.mosaic'),
+    configDefault: join(homedir(), '.config', 'mosaic'),
+  };
+  if (resolve(mosaicHome) !== resolve(homes.configDefault)) {
+    return mosaicHome;
+  }
+  return existsSync(join(homes.brain, 'fleet', 'agents')) ? homes.brain : mosaicHome;
+}
+
+/** True when fleet state resolves somewhere other than the config home. */
+export function brainHomeIsActive(mosaicHome: string, options: BrainHomeOptions = {}): boolean {
+  return resolve(resolveBrainHome(mosaicHome, options)) !== resolve(mosaicHome);
+}
+
+/** Fleet state root (brain home when active, else the config home). */
+export function fleetStateDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(resolveBrainHome(mosaicHome, options), 'fleet');
+}
+
+/** Seat launch envs — `<brainHome>/fleet/agents` when a brain is active. */
+export function fleetAgentEnvDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(fleetStateDir(mosaicHome, options), 'agents');
+}
+
+/** PRESERVE-protected persona override layer — `<brainHome>/fleet/roles.local`. */
+export function fleetRolesLocalDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(fleetStateDir(mosaicHome, options), 'roles.local');
+}
+
+/** System-type profiles (user working copies) — `<brainHome>/fleet/profiles`. */
+export function fleetProfilesDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(fleetStateDir(mosaicHome, options), 'profiles');
+}

packages/mosaic/src/fleet/fleet-reconciler.ts

@@ -3,6 +3,7 @@ import { lstat, open, readFile, unlink, type FileHandle } from 'node:fs/promises
 import { randomUUID } from 'node:crypto';
 import { homedir } from 'node:os';
 import { join } from 'node:path';
+import { fleetAgentEnvDir } from './brain-home.js';
 import {
   applyPreparedAgentEnvironmentProjection,
   prepareAgentEnvironmentProjection,
@@ -617,7 +618,7 @@ function defaultPrepareProjections(
         (agent: FleetRosterV2Agent): Promise<PreparedAgentEnvironmentProjection> =>
           prepareAgentEnvironmentProjection({
             mosaicHome,
-            agentEnvDir: join(mosaicHome, 'fleet', 'agents'),
+            agentEnvDir: fleetAgentEnvDir(mosaicHome),
             agentName: agent.name,
             generated: projectRosterV2AgentGeneratedEnv(roster, agent),
           }),

packages/mosaic/src/fleet/generated-env-boundary.spec.ts

@@ -176,6 +176,52 @@ describe('generated fleet agent environment boundary', (): void => {
     expect((await stat(result.generatedPath)).mode & 0o777).toBe(0o600);
   });
 
+  it('brain home: accepts and writes projections under MOSAIC_BRAIN_HOME/fleet/agents', async (): Promise<void> => {
+    const savedBrainHome = process.env['MOSAIC_BRAIN_HOME'];
+    try {
+      cleanup = await mkdtemp(join(tmpdir(), 'mosaic-generated-env-'));
+      const mosaicHome = join(cleanup, 'config-home');
+      const brainHome = join(cleanup, 'brain');
+      const agentEnvDir = join(brainHome, 'fleet', 'agents');
+      process.env['MOSAIC_BRAIN_HOME'] = brainHome;
+
+      const result = await writeAgentEnvironmentProjection({
+        mosaicHome,
+        agentEnvDir,
+        agentName: 'coder0',
+        generated: generatedValues,
+      });
+
+      // Projection landed in the brain tree, not under the config home.
+      expect(result.generatedPath).toBe(join(agentEnvDir, 'coder0.env.generated'));
+      expect((await stat(join(brainHome, 'fleet'))).mode & 0o777).toBe(0o700);
+      expect((await stat(agentEnvDir)).mode & 0o777).toBe(0o700);
+      expect((await stat(result.generatedPath)).mode & 0o777).toBe(0o600);
+      await expect(stat(join(mosaicHome, 'fleet'))).rejects.toThrow();
+
+      // A config-home agentEnvDir is now REJECTED while the brain is active —
+      // the boundary must not silently split state across two trees.
+      let rejected: unknown;
+      try {
+        await writeAgentEnvironmentProjection({
+          mosaicHome,
+          agentEnvDir: join(mosaicHome, 'fleet', 'agents'),
+          agentName: 'coder1',
+          generated: { ...generatedValues, MOSAIC_AGENT_NAME: 'coder1' },
+        });
+      } catch (caught: unknown) {
+        rejected = caught;
+      }
+      expect(rejected).toBeInstanceOf(AgentEnvBoundaryError);
+    } finally {
+      if (savedBrainHome === undefined) {
+        delete process.env['MOSAIC_BRAIN_HOME'];
+      } else {
+        process.env['MOSAIC_BRAIN_HOME'] = savedBrainHome;
+      }
+    }
+  });
+
   it('regenerates desired keys, relocates safe legacy local data, and quarantines forbidden legacy input', async (): Promise<void> => {
     cleanup = await mkdtemp(join(tmpdir(), 'mosaic-generated-env-'));
     const mosaicHome = join(cleanup, 'mosaic');

packages/mosaic/src/fleet/generated-env-boundary.ts

@@ -2,6 +2,7 @@ import { createHash, randomUUID } from 'node:crypto';
 import { chmod, lstat, mkdir, readFile, rename, unlink, writeFile } from 'node:fs/promises';
 import { homedir } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
+import { fleetAgentEnvDir, resolveBrainHome } from './brain-home.js';
 import { compareCodePoints } from './deterministic-order.js';
 
 export type AgentEnvironmentKind = 'generated' | 'local';
@@ -528,12 +529,15 @@ async function validatePrivateProjectionDirectory(
   mosaicHome: string,
   agentEnvDir: string,
 ): Promise<void> {
-  const fleetDir = join(mosaicHome, 'fleet');
-  const expectedAgentEnvDir = join(fleetDir, 'agents');
+  // Brain-home split (canon §2): seat envs live under the brain home's
+  // fleet/agents when a brain is active; roster + templates stay config-home.
+  const expectedAgentEnvDir = fleetAgentEnvDir(mosaicHome);
   if (resolve(agentEnvDir) !== resolve(expectedAgentEnvDir)) {
     throw new AgentEnvBoundaryError('unsafe-directory', '(directory)', agentEnvDir);
   }
-  await assertManagedDirectoryIfPresent(mosaicHome, false);
+  const stateHome = resolveBrainHome(mosaicHome);
+  const fleetDir = join(stateHome, 'fleet');
+  await assertManagedDirectoryIfPresent(stateHome, false);
   await assertManagedDirectoryIfPresent(fleetDir, false);
   await assertManagedDirectoryIfPresent(agentEnvDir, true);
 }
@@ -543,8 +547,9 @@ async function ensurePrivateProjectionDirectory(
   agentEnvDir: string,
 ): Promise<void> {
   await validatePrivateProjectionDirectory(mosaicHome, agentEnvDir);
-  const fleetDir = join(mosaicHome, 'fleet');
-  await ensureManagedDirectory(mosaicHome, false);
+  const stateHome = resolveBrainHome(mosaicHome);
+  const fleetDir = join(stateHome, 'fleet');
+  await ensureManagedDirectory(stateHome, false);
   await ensureManagedDirectory(fleetDir, false);
   await ensureManagedDirectory(agentEnvDir, true);
 }