v1.13.15-codecontext-synth: forced second-inference synthesis for codecontext overview tools

After a codecontext overview-class tool call lands (get_codebase_overview,
get_framework_analysis, get_semantic_neighborhoods), the pipeline runs a
second inference pass that replaces the recursive runAssistantTurn. The
synth pass auto-fetches the top-N source files referenced in the
codecontext output plus project docs (BOOCHAT.md, AGENTS.md,
*roadmap*.md, CONTEXT.md), applies a 32k-token budget with explicit
drop-priority, and streams a structured response that grounds the model
in real load-bearing code rather than relying on the codecontext summary
alone. Smoke #1 (default) and #2 (Architect) both cite the correct
inference/turn.ts + tool-phase.ts + stream-phase.ts files; smoke #6
(fault injection) verifies the fall-through path marks the synth message
status='failed' and yields cleanly to the recursive turn.

## Truncation-aware extraction

codecontext's wrapper inline-truncates results at 32k chars. Without the
expansion step, the top-N file selection only saw the alphabetical head
of the codebase (apps/booterm/dist/*) and auto-fetched the wrong sources.
The pipeline now calls in-process readTruncation(outputPath) before
extracting referenced files, so top-N selection sees the full 80k+ char
output. The 32k truncated head still ships to the synth model — the
expansion is reference-extraction-only, preserving the token-budget
contract. Graceful degradation on readTruncation null/throw: log warn,
fall back to the truncated head.

## Schema deviation from dispatch

The dispatch claimed no schema migration was needed for the new
'synthesis' part kind. Reality: message_parts.kind has an explicit
CHECK constraint (schema.sql:54) that would reject the new value. Added
a DROP CONSTRAINT IF EXISTS + DO $$ pg_constraint idempotency-guarded
re-add matching the CLAUDE.md migration pattern. The inline CREATE TABLE
constraint also updated so fresh installs land with the extended enum.

## User-abort marks synth-message failed

Deviation from review-time spec ("user-abort path does NOT mark the
message failed"). The outer abort handler in error-handler.ts operates
on the parent turn's assistantMessageId, not the new synth row that
runSynthesisPass created. Without explicit marking, the synth row would
sit in status='streaming' until the 5-min stale-streaming sweeper
(v1.13.1-cleanup-bundle), tripping the frontend's 60s no-token-activity
banner in the meantime — exactly the UX bug class the v1.13.1 sweeper
was added to handle. Marking failed on every catch path (including
user-abort) closes the gap. Cost: one extra DB write + one publish on
the rare user-abort-during-synth path.

## Race-safe synth-tool capture

tool-phase.ts uses synthEntries: Array<{tc, output, error?}> with
per-callback push under Promise.all. find() picks the first non-error
entry by call-order (toolCalls array index). Multiple synth-tools in
one batch are uncommon but handled deterministically.

## Roadmap rebase

Updated boocode_roadmap.md retrospective section + cleanup-order tracker
+ schema-changes summary to use the new vMAJOR.MINOR.PATCH-slug tag
names per the 2026-05-22 retag (CHANGELOG.md is the canonical record).
v1.13.15 listed as "this batch, tag pending"; a one-line follow-up
commit will remove that qualifier after the tag lands.

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

apps/server/src/schema.sql

@@ -51,7 +51,7 @@ CREATE TABLE IF NOT EXISTS message_parts (
   kind text NOT NULL,
   payload jsonb NOT NULL,
   created_at timestamptz NOT NULL DEFAULT clock_timestamp(),
-  CONSTRAINT message_parts_kind_chk CHECK (kind IN ('text', 'tool_call', 'tool_result', 'reasoning', 'step_start')),
+  CONSTRAINT message_parts_kind_chk CHECK (kind IN ('text', 'tool_call', 'tool_result', 'reasoning', 'step_start', 'synthesis')),
   CONSTRAINT message_parts_seq_uniq UNIQUE (message_id, sequence)
 );
 CREATE INDEX IF NOT EXISTS message_parts_msg_seq_idx ON message_parts (message_id, sequence);
@@ -74,6 +74,23 @@ END $$;
 CREATE INDEX IF NOT EXISTS message_parts_hidden_idx
   ON message_parts (message_id) WHERE hidden_at IS NULL;
 
+-- v1.13.13: extend message_parts.kind to allow 'synthesis'. Existing DBs were
+-- created with the pre-v1.13.13 CHECK constraint that did NOT include
+-- 'synthesis'; drop + re-add the constraint with the extended enum. Fresh
+-- installs hit the inline constraint above (already updated) and skip this
+-- block via the pg_constraint guard.
+ALTER TABLE message_parts DROP CONSTRAINT IF EXISTS message_parts_kind_chk;
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM pg_constraint WHERE conname = 'message_parts_kind_chk'
+  ) THEN
+    ALTER TABLE message_parts
+      ADD CONSTRAINT message_parts_kind_chk
+      CHECK (kind IN ('text', 'tool_call', 'tool_result', 'reasoning', 'step_start', 'synthesis'));
+  END IF;
+END $$;
+
 -- v1.13.1-B: read-path view. Read sites SELECT FROM messages_with_parts
 -- instead of messages so tool_calls / tool_results / reasoning_parts come
 -- from the granular message_parts table. The COALESCE means pre-v1.13.0