feat: MCP {env:VAR} key substitution + coder model/tool-result fixes + docs refactor (v2.7.9)

- MCP secrets: substituteEnvVars recursively resolves {env:NAME} in mcp.json string values from process.env before Zod (opencode-compatible); unset -> '' + boot warning, and invalid-config log names the unset vars (an empty {env:VAR} in a strict url/command field invalidates the whole config)
- data/mcp.json now untracked (.gitignore flips !data/mcp.json -> !data/mcp.example.json); tracked template data/mcp.example.json carries "{env:CONTEXT7_API_KEY}"; .env.example documents the key (9 mcp-config tests)
- Coder fix: message_complete frame model widened string -> string|null (server+web ws-frames parity); dispatcher publishes model: task.model at all 4 external completion points — a null model otherwise fail-closed in publishFrame and dropped the whole frame incl. status:'complete' (regression test)
- Coder fix: claude-sdk mapUserToolResults maps user-message tool_result blocks -> terminal tool_update events (completed/failed w/ output) so tool snapshots resolve instead of spinning forever
- Composer: AgentComposerBar drops §9b resumed/history/new chip + token readout, loses flex-wrap so the row stays one line; CoderPane gains a per-chat localStorage agent-config cache (restores last model on reopen) + threads model into the timeline/chip
- Docs: root CLAUDE.md slimmed (~190 lines), per-app refs split to apps/{coder,server,web}/CLAUDE.md; new docs/coder-backends.md, docs/project-discovery.md, docs/coding-standards/ (cross-app-contract-parity); ARCHITECTURE.md links the backends doc

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/src/components/AgentComposerBar.tsx

@@ -5,7 +5,6 @@ import type { AgentSessionConfig, ProviderSnapshotEntry, AgentCommand } from '@/
 import { useProviderSnapshot, refreshProviderSnapshot } from '@/hooks/useProviderSnapshot';
 import type { AgentStatusEntry } from '@/hooks/useAgentStatus';
 import { providerIcon } from '@/components/coder/providerIcons';
-import { useAgentSessions } from '@/hooks/useAgentSessions';
 import {
   DropdownMenu,
   DropdownMenuContent,
@@ -174,16 +173,6 @@ interface Props {
   onChange: (next: AgentSessionConfig) => void;
   onProviderCommandsChange?: (commands: AgentCommand[]) => void;
   connected?: boolean;
-  // v2.6 Phase 1-UX §9b: chat id for the resumed/new-session chip. Optional so
-  // BooChat and any other AgentComposerBar caller renders no chip and is
-  // otherwise unaffected. When present + connected + the chat has ≥1 prior
-  // turn, a chip right of the Provider picker reports whether switching to the
-  // current provider resumes an agent session, replays history (boocode), or
-  // starts fresh.
-  sessionId?: string;
-  // True once the chat has at least one prior turn — gates the chip so it stays
-  // hidden on a brand-new chat. Defaults to false (no chip).
-  hasPriorTurn?: boolean;
   // #10: normalized status (working|blocked|idle|error) for the active external
   // agent in this chat, or null for native boocode / before any frame. Renders
   // a status dot DISTINCT from the WS-liveness `connected` dot. Undefined for
@@ -191,31 +180,6 @@ interface Props {
   agentStatus?: AgentStatusEntry | null;
 }
 
-// Condensed token count: 950 → "950", 12_400 → "12.4K", 3_200_000 → "3.2M".
-// Sub-1000 stays exact; thousands/millions get one decimal, trailing .0 trimmed.
-function abbrevTokens(n: number): string {
-  if (!Number.isFinite(n) || n < 1000) return String(Math.max(0, Math.round(n)));
-  if (n < 1_000_000) return `${(n / 1000).toFixed(1).replace(/\.0$/, '')}K`;
-  return `${(n / 1_000_000).toFixed(1).replace(/\.0$/, '')}M`;
-}
-
-// Relative-time formatter for the resumed-chip title (e.g. "3m ago").
-function relativeTime(iso: string | null): string {
-  if (!iso) return 'unknown';
-  const then = new Date(iso).getTime();
-  if (Number.isNaN(then)) return 'unknown';
-  const diffMs = Date.now() - then;
-  if (diffMs < 0) return 'just now';
-  const sec = Math.floor(diffMs / 1000);
-  if (sec < 60) return 'just now';
-  const min = Math.floor(sec / 60);
-  if (min < 60) return `${min}m ago`;
-  const hr = Math.floor(min / 60);
-  if (hr < 24) return `${hr}h ago`;
-  const day = Math.floor(hr / 24);
-  return `${day}d ago`;
-}
-
 // #10: normalized external-agent status dot. Mirrors StatusDot's visual
 // language but on the four normalized buckets (working|blocked|idle|error),
 // and is DISTINCT from the WS-liveness `connected` dot beside it:
@@ -251,7 +215,7 @@ function AgentStatusDot({ entry, agent }: { entry: AgentStatusEntry; agent: stri
   );
 }
 
-export function AgentComposerBar({ projectPath, value, onChange, onProviderCommandsChange, connected, sessionId, hasPriorTurn, agentStatus }: Props) {
+export function AgentComposerBar({ projectPath, value, onChange, onProviderCommandsChange, connected, agentStatus }: Props) {
   const allEntries = useProviderSnapshot(projectPath);
   // 5.5 — the composer picker only offers ENABLED providers that are ready (or
   // still loading). Disabled (enabled:false) and unavailable/error providers are
@@ -263,13 +227,6 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
   );
   const [refreshing, setRefreshing] = useState(false);
 
-  // v2.6 Phase 1-UX §9b: chat-scoped agent-session rows for the resumed/new
-  // chip. Hook is unconditional (hooks rule); it self-no-ops when sessionId is
-  // undefined or the chat has no prior turn, so BooChat callers cost nothing.
-  const { sessions: agentSessions } = useAgentSessions(
-    sessionId && hasPriorTurn ? sessionId : undefined,
-  );
-
   const hydratedRef = useRef(false);
 
   useEffect(() => {
@@ -383,42 +340,8 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
   const modelOptions = (currentEntry?.models ?? []).map((m) => ({ id: m.id, label: m.label }));
   const thinkingOpts = thinkingOptions.map((t) => ({ id: t.id, label: t.label }));
 
-  // v2.6 Phase 1-UX §9b: resumed / history / new-session chip. Only meaningful
-  // when this is a real chat (sessionId), the WS is connected, and the chat has
-  // ≥1 prior turn — otherwise render nothing so fresh chats and non-coder
-  // callers stay clean.
-  const sessionRow = agentSessions.find((s) => s.agent === value.provider);
-  const sessionChip: { label: string; title: string } | null =
-    sessionId && hasPriorTurn && connected
-      ? value.provider === 'boocode'
-        ? // Native boocode never holds an agent_sessions row — it reconstructs
-          // the conversation from the chat transcript each turn.
-          { label: 'history', title: 'BooCode replays the chat transcript each turn' }
-        : sessionRow?.has_session
-          ? {
-              label: 'resumed',
-              title: `Resuming ${value.provider} · last active ${relativeTime(sessionRow.last_active_at)}`,
-            }
-          : { label: 'new session', title: `${value.provider} starts a fresh session this turn` }
-      : null;
-
-  // sampling-streamjson-tokens #8: condensed per-(chat,agent) token/cost readout
-  // beside the session chip. Coerce — input/output are BIGINT (string over wire).
-  // Hidden when no session row or all totals are zero (e.g. native boocode, which
-  // holds no agent_sessions row, or a provider that hasn't run yet).
-  const usageReadout = (() => {
-    if (!sessionChip || !sessionRow) return null;
-    const inTok = Number(sessionRow.input_tokens) || 0;
-    const outTok = Number(sessionRow.output_tokens) || 0;
-    const cost = Number(sessionRow.cost) || 0;
-    if (inTok <= 0 && outTok <= 0 && cost <= 0) return null;
-    const parts = [`${abbrevTokens(inTok)} in`, `${abbrevTokens(outTok)} out`];
-    if (cost > 0) parts.push(`$${cost.toFixed(2)}`);
-    return parts.join(' · ');
-  })();
-
   return (
-    <div className="flex flex-wrap items-center gap-1 px-2 py-1 border-b border-border bg-muted/20 shrink-0">
+    <div className="flex items-center gap-1 px-2 py-1 border-b border-border bg-muted/20 shrink-0">
       <CompactPicker
         label="Provider"
         value={value.provider}
@@ -430,22 +353,6 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
             : providerIcon(value.provider)
         }
       />
-      {sessionChip && (
-        <span
-          title={sessionChip.title}
-          className="inline-flex items-center rounded-full border border-border bg-muted/40 px-1.5 py-0.5 text-[10px] font-medium text-muted-foreground shrink-0"
-        >
-          {sessionChip.label}
-        </span>
-      )}
-      {usageReadout && (
-        <span
-          className="text-[10px] text-muted-foreground tabular-nums whitespace-nowrap shrink-0"
-          title="Tokens in · out · cost for this agent session"
-        >
-          {usageReadout}
-        </span>
-      )}
       <CompactPicker
         label="Mode"
         value={value.modeId ?? ''}
@@ -472,8 +379,7 @@ export function AgentComposerBar({ projectPath, value, onChange, onProviderComma
           icon={<Brain className="size-3 shrink-0" />}
         />
       )}
-      {/* Status dot + refresh as one right-aligned unit so the refresh button
-          stays on the top line instead of wrapping past the edge-pinned dot. */}
+      {/* Status dot + refresh — pinned right (ml-auto), never on its own line. */}
       <div className="ml-auto flex items-center gap-1 shrink-0">
         {/* #10: normalized agent status — only for an external agent with a
             live status frame. Distinct from the WS-liveness dot that follows. */}