feat(app): live session update + tool renderer + input_tokens migration

SessionDetail live update:
- Extract session-view-state.mjs: capture scroll position, disclosure
  (open/skill-md-open) state, and visible-UUID anchor before refresh;
  reconcile messages by UUID (in-place update, append tail only); restore
  scroll and disclosure state after DOM patch. findLastMessageAtOrAbove uses
  binary search (O(log n)) instead of linear scan.
- scrollRevision tracks user scrolls during refresh to avoid stale anchors
  overriding manual navigation.
- Throttle onScroll to one rAF per frame.

Tool renderer:
- Extract tool-renderer.js: standalone module for rendering tool call cards
  (Read/Write/Edit diffs, Bash terminal output, search results, JS/TS
  syntax highlighting). Replaces inline rendering in SessionDetail.
- tests/app-tool-renderer.test.mjs covers escaping, highlighting, and
  terminal formatting.

Input tokens semantics migration:
- Claude provider now sums input_tokens + cache_creation_input_tokens +
  cache_read_input_tokens into a single input_tokens value (was previously
  only the raw field, undercounting when cache tokens are present).
- One-time index-wide re-parse triggered when the marker
  __claude_input_tokens_include_cache_v1__ is absent and the DB already
  has token data (self-healing on first build after upgrade).
- App indexer.ts carries the same marker check for the app's build path.

Also:
- PRODUCT.md: product register (users, purpose, brand, design principles,
  accessibility targets).
- README.md: minor wording updates.

Co-Authored-By: Codex (GPT-5) <noreply@openai.com>

packages/core/src/indexer.ts

@@ -8,7 +8,10 @@ import { persist } from './persist.ts';
 import { nodeSqliteTransactionAdapter } from './tx.ts';
 import { acquireWriterLease, writerLockPathFor } from './writer-lease.ts';
 import { runRetryableWriteTransaction, isBeginBusyFailure, hasUnusableTransaction } from './write-coordinator.ts';
-import { parse as claudeParse } from './providers/claude.ts';
+import {
+  CLAUDE_INPUT_TOKEN_SEMANTICS_MARKER,
+  parse as claudeParse,
+} from './providers/claude.ts';
 import { parse as codexParse } from './providers/codex.ts';
 import type { Cursor, IndexRecord } from './providers/types.ts';
 import type { ClaudeJsonlFile } from './parsing.ts';
@@ -210,7 +213,17 @@ function buildIndex({ force = false }: { force?: boolean } = {}) {
 
     const db = openDb();
     const txDb = nodeSqliteTransactionAdapter(db);
+    const claudeInputMarkerMissing = !db.prepare(
+      'SELECT jsonl_path FROM index_state WHERE jsonl_path = ?',
+    ).get(CLAUDE_INPUT_TOKEN_SEMANTICS_MARKER);
+    const claudeInputSemanticsOutdated = claudeInputMarkerMissing && Boolean(db.prepare(`
+      SELECT 1 FROM messages
+      WHERE COALESCE(source, 'claude') = 'claude'
+        AND (input_tokens IS NOT NULL OR output_tokens IS NOT NULL)
+      LIMIT 1
+    `).get());
     const skippedFiles: SkippedFile[] = [];
+    let claudeInputMigrationFailed = false;
     try {
       try {
         if (force) {
@@ -261,9 +274,10 @@ function buildIndex({ force = false }: { force?: boolean } = {}) {
               // (docs/adr/0001). needsReindex keeps the "skip unchanged file" fast path;
               // the cursor's line count drives incremental resume inside parse().
               const { needed, skip } = needsReindex(db, f.path);
-              if (needed) {
+              if (needed || claudeInputSemanticsOutdated) {
                 const unit = { key: f.path, sessionId: f.sessionId, project: f.project, isSubagent: f.isSubagent, agentId: f.agentId };
-                persist(db, unit, claudeParse(unit, skip > 0 ? `0:${skip}` : null));
+                const cursor = !claudeInputSemanticsOutdated && skip > 0 ? `0:${skip}` : null;
+                persist(db, unit, claudeParse(unit, cursor));
               }
               indexSubagentMeta(db, f);
             }
@@ -273,6 +287,9 @@ function buildIndex({ force = false }: { force?: boolean } = {}) {
             return { skip: true, reason: 'database_busy', skipped: skippedFiles.length, skippedFiles };
           }
           if (hasUnusableTransaction(e)) throw e;
+          if (claudeInputSemanticsOutdated && f.source !== 'codex') {
+            claudeInputMigrationFailed = true;
+          }
           // A per-file failure is skippable: log and move on.
           const error = e as { message?: unknown; obelisk?: unknown } | null;
           const message = errorMessage(e);
@@ -291,6 +308,10 @@ function buildIndex({ force = false }: { force?: boolean } = {}) {
           db.exec("INSERT INTO messages_fts(messages_fts) VALUES('rebuild')");
           rebuildMemoryFts(db);
           db.prepare("INSERT OR REPLACE INTO index_state (jsonl_path, mtime, lines_processed) VALUES ('__last_build__', ?, 0)").run(Date.now());
+          if (!claudeInputSemanticsOutdated || !claudeInputMigrationFailed) {
+            db.prepare('INSERT OR REPLACE INTO index_state (jsonl_path, mtime, lines_processed) VALUES (?, ?, 0)')
+              .run(CLAUDE_INPUT_TOKEN_SEMANTICS_MARKER, Date.now());
+          }
         }, { label: 'finalize' });
       } catch (error) {
         if (isBeginBusyFailure(error)) {