docs: say what these things are, not where they used to be

mara on #3923: "past tense is itself a smell for docs, we dont need any
'used to be somewhere else'" and "any gate we add should not have false
positives". Those are one instruction: the entire false-positive set of a
repo-path checker was prose naming files that are deliberately gone, so
removing the prose is what lets the gate be strict instead of carrying a
skip-list nobody maintains.

Three sites, and only two of them are past tense:

`agent-hierarchy.md` named two removed modules to explain that a code path
is gone. A reader cannot act on where it used to live; they can act on
where cancellation happens now, which is the half the sentence buried.

`term_msg.rs` carried a "Design history" paragraph whose live content was
three rules -- classification is server-side, `level` carries styling, four
named fields are deliberately absent -- wrapped in narration about a
redesign and a pointer to a deleted frontend file. Restated as the rules.

`gotchas.md` is NOT past tense: it correctly names a file in the website
repo. Qualifying it as `hyperhive/website:nix/options.nix` did not work --
the extractor still matches `nix/options.nix` as a substring, so the fix
has to be prose that contains no repo-relative path at all. Naming the
file alone does that and reads better.

Verified against this tree rather than the default checkout: the audit
script takes a directory argument and defaults elsewhere, so its first
(unchanged) DEAD:3 was a true statement about a different branch. On this
one: DEAD 3 -> 0, 141 distinct paths enumerated, and an injected dead path
is still caught.

Refs #3923

docs/agent-lifecycle/agent-hierarchy.md

@@ -155,11 +155,9 @@ Manager}` switch picks the MCP tool allow-list claude sees. Both are
   ancestor/descendant check instead of a manager-name check — see the
   module docs for `loose_ends.rs`, `stores/broker.rs`, `actions.rs`,
   and `workers/crash_watch.rs` for the current owner-check logic in
-  each. (Question/answer routing and its own manager-override cancel
-  path — formerly `hive-c0re/src/questions.rs` and
-  `stores/operator_questions.rs` — has been removed entirely; reminder
-  cancellation is now handled fully in-agent, see the note on
-  `CancelLooseEndKind::Reminder` in `hive-c0re/src/socket_server/mod.rs`.)
+  each. (Reminder cancellation is handled fully in-agent — see the note
+  on `CancelLooseEndKind::Reminder` in
+  `hive-c0re/src/socket_server/mod.rs`.)
 
 None of the above is a stable interface — treat the module doc
 comments as the source of truth for exactly which checks exist today.

docs/process/gotchas.md

@@ -472,7 +472,7 @@ Pipeline:
 - CommonMark from `nixosOptionsDoc.optionsCommonMark` is the only
   output — the source of truth, emitted as `.md`.
 - **HTML + CSS is rendered downstream by the website repo**
-  (`nix/options.nix` there), which consumes this bundle's `host.md` /
+  (its own `options.nix`), which consumes this bundle's `host.md` /
   `agent.md`, renders them with `cmark-gfm`, and shares one
   stylesheet (`docs.css`) across `/options/` and the prose `/docs/`
   tree. Keeping rendering in the website means the theme has a single

hive-agent/src/term_msg.rs

@@ -10,14 +10,12 @@
 //! `stream-json` line) can expand to several: an `assistant` message with
 //! both a text block and a `tool_use` block produces two rows.
 //!
-//! Design history: mara's terminal-message redesign (six rounds of
-//! negotiation on the forge) collapsed what was an 11-field frontend-side
-//! row shape (`StreamRow`, `frontend/packages/agent/src/lib/streamRow.ts`)
-//! plus raw claude-JSON passthrough into this 6-field shape, with
-//! classification moved server-side so the client-side `classifyEvent.ts` —
-//! a large per-tool dispatch table — mostly goes away. `kind`, `unread`,
-//! `from`, and `expanded_default` were all considered and dropped along the
-//! way; `level` replaces free-text CSS-class styling.
+//! Six fields, and classification belongs **here**, not in the client: the
+//! web UI renders what it is handed and owns no per-tool dispatch table, so
+//! a new tool needs no frontend change. `level` carries styling, so a row
+//! never names a CSS class. `kind`, `unread`, `from` and `expanded_default`
+//! are deliberately absent — adding one back is a design change, not an
+//! oversight.
 
 use serde::Serialize;
 use std::collections::HashMap;