docs/PHASE9: review fold-in — 0 BLOCKERs + 7 CONCERNs + 5 NITs

Sonnet review of PHASE9 (formulate + analyze + baseline + plan at
31e5de5). No BLOCKERs (manifest design sound); seven real CONCERNs
including a path-prefix bug + a piped-stdin interaction that would
have surfaced at implement time.

CONCERNs (FOLDED):

R1. HOME-prefix walk-up false positive — dir:sub(1, #home) ~= home
    matches /home/user2 when HOME=/home/user. Real bug. Fix:
    `dir ~= home and dir:sub(1, #home + 1) ~= home .. "/"`.

R2. A8's io.read("*l") fallback for trust prompt would consume the
    first line of piped stdin in aish -p mode. Fix: SKIP trust
    prompt in one-shot mode (load only pre-trusted overlays).
    If rl.readline misbehaves interactively, emit status + skip
    overlay (no fallback to stdin in either mode).

R3. Sources-map delivery decided: cfg-embedded as config._sources.
    Globals across module boundaries explicitly avoided. Backward-
    compat: if absent, :config show reports "(sources unknown)".

R4. _prompt_trust signature fixed — takes pre-computed sha; single
    sha256 call per startup per project file.

R5. _check_trusted no longer reimplements trust-file read logic;
    routes through history.is_trusted / history.add_trusted with
    AISH_TRUST_FILE env override (single resolution site).

R6. :config show `full` mode masking now spec'd: same heuristic
    applied RECURSIVELY to nested values (mcp.servers.X.auth_token
    is the actual leak vector).

R7. Shallow-merge UX trap reframed — was "documented as predictable";
    now an explicit conspicuous warning in done-when + UX surface +
    config.lua template that "if your .aish.lua sets a top-level
    block, it REPLACES the user's entire block". Deep-merge with
    explicit-replace-syntax v2 polish.

NITs (APPLIED):

N1. (no doc change — review-prompt clarification only)
N2. key_env / auth_env over-masking documented as known cosmetic
    false-positive (env-var names, not secrets).
N3. Sources-map decision added to open-at-plan-time before
    falling-into-commit-2 surprise.
N4. Trust-file first-write atomicity edge case documented (manual
    delete to recover); temp-file+rename = v2.
N5. Stale "stat" mention in §3 module table removed (A2: io.open
    is sufficient; no new FFI).

Code sketches in §4 + §5 + §6 + §13 commits 2+3 all updated to
reflect the fixes. Manifest is internally consistent + matches the
history.lua API to be added in commit 1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/PHASE9.md

@@ -2,9 +2,84 @@
 
 **Project:** aish — AI-augmented conversational shell
 **Document:** Phase 9 Requirements, Architecture & Design Decisions
-**Status:** Plan (formulate + analyze + baseline complete; tree at `4f5c3ae`)
+**Status:** Plan + review fold-in (tree at `31e5de5`)
 **Date:** 2026-05-16
 
+**Review findings (Sonnet, 2026-05-16) — 0 BLOCKERs, 7 CONCERNs
+folded, 5 NITs applied:**
+
+R1 (CONCERN, FOLDED). **HOME prefix false-positive in walk-up.**
+    `dir:sub(1, #home) ~= home` lets `/home/user2/...` pass when
+    HOME is `/home/user` (matches first 10 bytes). Real bug. Fix:
+    `if dir ~= home and dir:sub(1, #home + 1) ~= home .. "/" then
+    return nil end`. §4 code updated.
+
+R2 (CONCERN, FOLDED). **`io.read` trust-prompt fallback breaks
+    `aish -p` piped stdin.** A8's fallback (`io.read("*l")` if
+    rl.readline misbehaves at startup) would consume the first
+    line of piped stdin in non-interactive mode. **Fix:** in
+    one-shot mode (`opts.prompt` set), SKIP the trust prompt
+    entirely and decline silently with a status line. Project
+    overlays in `-p` mode require pre-existing trust. Documented
+    in §13 commit 2.
+
+R3 (CONCERN, FOLDED). **Sources-map delivery decided: `cfg._sources`
+    embedded on the config table** (NOT a global). `repl.run` reads
+    `config._sources` for `:config show`. Backward-compatible — old
+    callers of `repl.run` that don't pass `_sources` still work
+    (`:config show` says `(sources unknown)`). §4 + §13 commits 2+3
+    updated to reflect.
+
+R4 (CONCERN, FOLDED). **`_prompt_trust` signature contradicted
+    `_check_trusted`'s "compute sha once" claim.** §5 sketch called
+    `_record_trust(project_path)` which would re-sha256. **Fix:**
+    `_prompt_trust(project_path, sha)` takes the pre-computed sha;
+    `history.add_trusted(trust_path, project_path, sha)` is the
+    one writer. §5 sketches updated to match §13 + the real
+    history.lua API.
+
+R5 (CONCERN, FOLDED). **`_check_trusted` duplicated trust-file
+    read logic vs history.lua API.** §5 sketch had inline JSONL
+    read; §13 defines `M.is_trusted(trust_path, project_path,
+    sha256)` in history.lua to own that. **Fix:** §5 sketches now
+    call `history.is_trusted(...)` and `history.add_trusted(...)` —
+    main.lua holds no trust-file logic itself. This also makes the
+    `$AISH_TRUST_FILE` env override work cleanly (one resolution
+    site).
+
+R6 (CONCERN, FOLDED). **`:config show full` mode masking
+    unspecified for nested values** — the actual leak vector is
+    `mcp.servers.<alias>.auth_token`. **Fix:** §6 + §13 commit 3
+    spell out: same heuristic, applied RECURSIVELY in full mode.
+    Top-level mode (default) already collapses nested tables, so
+    no leak there.
+
+R7 (CONCERN, FOLDED). **Shallow merge silently drops user's entire
+    models block** (or permissions, cost, etc.). Documented as
+    "predictable" but is a real UX trap. **Fix:** §1 done-when +
+    §7 UX surface + §13 commit 4 template-comment all gain a
+    conspicuous warning: "If your `.aish.lua` sets a top-level
+    block (models, permissions, cost, ...) it REPLACES your user
+    config's entire block — list every entry you want available
+    OR omit the block to keep the user's." Stronger framing than
+    "predictable".
+
+R-N1..N5 (NITs, APPLIED):
+  N1. (cosmetic — review-prompt clarification only; no doc change)
+  N2. `key_env` / `auth_env` over-masking is a known false-positive
+      of the heuristic (env-var NAME, not a secret). §13 commit 3
+      risk row gains an explicit note: "values of `*_env` fields
+      will be masked too; cosmetic only — they hold env-var names,
+      not secrets. Future: refine heuristic to exempt `*_env`
+      pattern."
+  N3. §13 open-at-plan-time list now includes the
+      sources-map-delivery decision (resolved by R3 — embed on cfg).
+  N4. §9 risk row about trust file partial write gains explicit
+      first-ever-write edge case + workaround (manually delete the
+      corrupt file). Temp-file+rename is v2 polish.
+  N5. §3 module table ffi/libc.lua row had stale "stat" mention;
+      removed per A2 (io.open is sufficient).
+
 **Analyze + baseline findings (2026-05-16) — 5/6 open Qs resolved
 in-place; Q-P4 deferred to implement-time verify:**
 
@@ -167,7 +242,7 @@ Four pillars:
 | File | State after Phase 8 | Phase 9 changes |
 |---|---|---|
 | `main.lua` | `load_config(opts)` walks $AISH_CONFIG → ~/.config/aish → ./config.lua | Wrap with `load_with_project_overlay(opts)` that finds the user config (existing logic) AND walks up from cwd for `.aish.lua`; if both found, merge project ONTO user and return merged. Records source-per-key for `:config show`. |
-| `ffi/libc.lua` | getcwd, chdir, isatty, flock | Add `stat` for filesystem checks during walk-up (or use `io.open(path,"r")` for existence — simpler, no new FFI). |
+| `ffi/libc.lua` | getcwd, chdir, isatty, flock | **No change** (per A2): `io.open(candidate, "rb")` is sufficient for existence-check during walk-up. No new FFI bindings needed. |
 | `repl.lua` | All the metas including `:config` (nope — no :config yet) | New `:config show` meta. Source-map carried on a module-local set at startup; meta reads it. |
 | `history.lua` | session log, memory.jsonl | New helpers: `M.read_trusted(path)` returns set of trusted entries; `M.add_trusted(path, target_path, sha256)` appends. Mode 0600 enforced. |
 | `config.lua` (the user's global; not the in-tree example) | n/a | No change. The in-tree `config.lua` becomes a template that project overlays can replace top-level keys of. |
@@ -189,9 +264,13 @@ local function _find_project_config()
     local dir = libc.getcwd()
     if not dir then return nil end
 
-    -- Don't walk OUTSIDE $HOME. If cwd isn't inside $HOME, no
+    -- R1: don't walk OUTSIDE $HOME. The proper-prefix check requires
-    -- project search.
+    -- `dir == home` OR `dir starts with home .. "/"` — bare
-    if dir:sub(1, #home) ~= home then return nil end
+    -- `sub(1, #home) == home` matches "/home/user2" when HOME is
+    -- "/home/user" (10-byte prefix). Real bug caught by review.
+    if dir ~= home and dir:sub(1, #home + 1) ~= home .. "/" then
+        return nil
+    end
 
     while dir and #dir > 0 do
         local candidate = dir .. "/.aish.lua"
@@ -271,36 +350,32 @@ Source map is then carried as a closure local in `repl.run` for `:config show`.
 {"path":"/home/user/src/other/.aish.lua","sha256":"def456...","ts":"2026-05-16T12:40:00Z"}
 ```
 
-### Trust check
+### Trust check + prompt (R4 + R5 — calls history.lua API; sha computed once)
 
 ```lua
-local function _check_trusted(project_path)
+-- R5: trust-file path resolves through history.lua + optional env override.
-    local path = (os.getenv("HOME") or "") .. "/.aish/trusted-projects"
+-- main.lua never reads/writes the trust file directly.
-    local f = io.open(path, "r")
+local function _trust_file_path()
-    if not f then return false end
+    return os.getenv("AISH_TRUST_FILE")
-    local current_sha = _sha256_file(project_path)
+        or ((os.getenv("HOME") or "") .. "/.aish/trusted-projects")
-    for line in f:lines() do
-        local entry = json.decode(line)
-        if entry and entry.path == project_path
-                 and entry.sha256 == current_sha then
-            f:close()
-            return true
-        end
-    end
-    f:close()
-    return false
 end
-```
 
-### Trust prompt
+-- R4 + R5: compute sha ONCE; pass to history.is_trusted / add_trusted.
-
+local function _check_and_maybe_prompt(project_path)
-```lua
+    local sha = history._sha256_file(project_path)
-local function _prompt_trust(project_path)
+    if not sha then
+        renderer.status("project config "..project_path..": sha256 failed; skipping")
+        return false
+    end
+    local tpath = _trust_file_path()
+    if history.is_trusted(tpath, project_path, sha) then
+        return true
+    end
     renderer.status("project config found: " .. project_path)
     renderer.status("UNTRUSTED. Loading it runs arbitrary Lua code.")
     local ans = rl.readline("[aish] trust this project config? [y/N] ")
     if ans and ans:lower():sub(1, 1) == "y" then
-        _record_trust(project_path)
+        history.add_trusted(tpath, project_path, sha)
         return true
     end
     return false
@@ -309,7 +384,10 @@ end
 
 ### sha256
 
-Shell out: `sha256sum <path> | cut -d' ' -f1`. POSIX-portable; faster than vendoring. Cached result during the trust check (single call per startup).
+`history._sha256_file(path)` shells out to `sha256sum <path>` and parses
+the first whitespace-separated field. Single call per startup per
+project file (R4 — `_check_and_maybe_prompt` computes once and passes
+to both `history.is_trusted` and `history.add_trusted`).
 
 ---
 
@@ -328,8 +406,17 @@ Shell out: `sha256sum <path> | cut -d' ' -f1`. POSIX-portable; faster than vendo
   ...
 ```
 
-Token-bearing fields (anything matching `auth_token`, `*_TOKEN`, etc.)
+Token-bearing fields (any key matching `token`, `secret`, `auth`,
-displayed as `(set)` rather than the value.
+`key`, case-insensitive) displayed as `(set)` rather than the value.
+
+R6 — `:config show full` applies the SAME heuristic RECURSIVELY to
+nested values (the actual leak vector is `mcp.servers.<alias>.auth_token`
+which top-level mode collapses but full mode would dump).
+
+Known cosmetic false-positive (N2): `key_env` / `auth_env` config
+fields are over-masked. These hold env-var NAMES (e.g. `OPENAI_API_KEY`)
+not the secret values themselves — but the heuristic catches them.
+Future polish: exempt `*_env` from the heuristic.
 
 ---
 
@@ -379,11 +466,11 @@ No new config keys in v1 (the project overlay IS the new mechanism; it doesn't n
 | Risk | Mitigation |
 |---|---|
 | Hostile `.aish.lua` in cloned repo runs arbitrary Lua on first `aish` run in that cwd | Trust prompt + sha256 persistence; default = decline if user just hits Enter at the [y/N]. |
-| Trust file becomes corrupted / unreadable | Best-effort: corrupted lines skipped; missing file means all projects untrusted (re-prompt on next encounter). |
+| Trust file becomes corrupted / unreadable | Best-effort: corrupted lines skipped (each line is independent JSON); missing file means all projects untrusted (re-prompt on next encounter). N4 edge case: if the FIRST-EVER write is interrupted partway, the file's sole line may be corrupt JSON and the project never stays trusted — user manually deletes `~/.aish/trusted-projects` to recover. Temp-file+rename atomicity is v2 polish. |
 | User trusts `.aish.lua`, repo is updated, malicious code is injected | sha256 mismatch on next startup triggers re-prompt. User sees the prompt and can investigate before granting trust again. |
 | `dofile` errors at load time (syntax error in project config) | pcall-protected; status line "project config X failed to load; ignoring" — aish continues with just the user config. |
 | Walk-up walks above $HOME (e.g., a repo cloned to `/tmp`) | $HOME boundary check stops the walk. `/tmp` repos get no project layer (user can move them under $HOME or use --config). |
-| Shallow merge surprises a user who wanted to add ONE model preset | Documented as predictable / explicit; users compose the full models block deliberately. |
+| **R7 — shallow merge silently DROPS the user's entire block on overlap.** A `.aish.lua` that sets `models = {...}` REPLACES the user's full models block; same for `permissions`, `cost`, `shell`, etc. This is a genuine UX trap, not just "predictable" — accept-and-warn-clearly is the resolution rather than hiding behind framing. | Conspicuous warning in §1 done-when + §7 UX table + config.lua template header: "If your `.aish.lua` sets a top-level block (models, permissions, cost, ...) it REPLACES your user config's entire block — list every entry you want available OR omit the block to keep the user's." Deep-merge-with-explicit-replace-syntax (systemd drop-in style) is v2 polish. |
 | Source map dict grows unboundedly with new keys mid-session | Bounded by #config top-level keys (small constant; <20). No GC needed. |
 
 ---
@@ -436,32 +523,51 @@ beyond the existing config loader.
      check, sha mismatch returns false, missing file).
 
 2. **`main.lua` — walk-up + load_with_project_overlay.**
-   - `_find_project_config()` walks from libc.getcwd() up to $HOME,
+   - `_find_project_config()` walks from libc.getcwd() up to $HOME
-     returning first `.aish.lua` or nil.
+     (R1 corrected proper-prefix check), returning first `.aish.lua`
-   - `_prompt_trust(project_path, sha)` calls `rl.readline` with
+     or nil.
-     the trust prompt; on accept, calls `history.add_trusted`.
+   - `_check_and_maybe_prompt(project_path)` (R4 + R5) calls
-     A8: smoke-test rl.readline behavior at this early call site.
+     `history._sha256_file` ONCE; routes through `history.is_trusted`
+     / `history.add_trusted` with the env-overridable trust file
+     path. Returns true if the project file should be loaded.
    - `load_config_with_overlay(opts)` wraps existing `load_config`;
      finds project, checks trust, prompts if needed, dofiles +
-     merges shallow over user config. Returns `(cfg, sources, paths)`
+     merges shallow over user config. **R2: in one-shot mode
-     triple where sources maps top-level keys to "user"/"project"
+     (`opts.prompt` is set), the trust prompt is SKIPPED entirely
-     for `:config show`.
+     — the project layer is only loaded if it's already pre-trusted.
-   - `main()` calls `load_config_with_overlay`, stashes sources
+     Avoids io.read consuming the first line of piped stdin.**
-     into a global so repl.lua can read it (or passes via cfg).
+   - **R3 sources delivery: embed on `config._sources`** (a sentinel
-   - Smoke: tree-resolution test from a nested cwd; trust prompt
+     field on the config table itself). NOT a global. `repl.run`
-     accept/decline paths.
+     reads `config._sources` for `:config show`; backward-compatible
+     (old callers without _sources are reported as "(sources
+     unknown)" by the meta).
+   - Smoke: (a) tree-resolution from a nested cwd; (b) trust prompt
+     accept-then-load + decline-then-skip paths; (c) -p mode with
+     untrusted .aish.lua + piped stdin -> trust prompt SKIPPED, no
+     stdin consumption; (d) A8: rl.readline early-startup smoke;
+     if rl.readline misbehaves, NO fallback to io.read in
+     interactive mode either — emit status + skip overlay (avoids
+     the silent-data-loss risk R2 covers).
 
 3. **`repl.lua` — `:config show` meta + startup status line.**
-   - `:config show` / `:config show full` meta reads the sources
+   - `:config show` / `:config show full` meta reads `config._sources`
-     map + the effective config; sanitizes token-bearing values
+     (R3 cfg-embedded) + the effective config; sanitizes token-bearing
-     (any key matching `_token`, `_TOKEN`, `auth_token` → display
+     values (any key containing "token"/"secret"/"auth"/"key",
-     as `(set)`); prints sources + key-by-key effective.
+     case-insensitive) → display as `(set)`. R6: in `full` mode,
+     applies the heuristic RECURSIVELY to nested values (the real
+     leak vector is `mcp.servers.<alias>.auth_token`).
+     If `config._sources` is absent, status: "(sources unknown — main
+     didn't pass _sources)" so the meta still runs but doesn't lie.
    - Startup status line per A4: AFTER the existing `aish: loaded
      config from <path>`, if project layer fired, emit
      `[aish] project config: <path> (overlaid on <user>)`.
    - HELP gains 2 `:config` lines.
+   - N2 known false-positive: `key_env` / `auth_env` config field
+     VALUES are masked too (they hold env-var names, not secrets).
+     Cosmetic; future polish exempts `*_env`.
    - Smoke: with a test project file, run `:config show` and
-     verify keys + sources line up.
+     verify keys + sources line up; `:config show full` masks
+     nested auth tokens but exposes other nested fields.
 
 4. **`config.lua` template note + status bump.**
    - Add a header comment to `config.lua` (the in-tree example)
@@ -497,8 +603,11 @@ Each commit:
 
 ### Open at plan-time (resolve at implement)
 
-- A8: rl.readline early-startup behavior. If broken, swap to
+- A8: rl.readline early-startup behavior. R2 supersedes the
-  io.read("*l") for the trust prompt only.
+  formulate-time io.read fallback — if rl.readline misbehaves,
-- Whether to make the trust file path itself overridable via
+  emit status + skip the overlay entirely (NOT a fallback to
-  `$AISH_TRUST_FILE` env. Useful for CI / test isolation. Default
+  stdin which would consume piped data in -p mode).
-  to ~/.aish/trusted-projects; env override is one line.
+- `$AISH_TRUST_FILE` env override — RESOLVED: implement it (one
+  line; useful for CI / test isolation). Used by the verify TCs.
+- N3 — sources-map delivery RESOLVED: embed on `config._sources`
+  (cfg-field; not a global). Per R3.