RMKDQ3

The server implements concurrency using pure‑Rust primitives: a per‑connection thread (thread::spawn) and a shared Arc‑wrapped Store guarded by a Mutex. All indexing, query execution, and transaction handling are done via in‑memory data structures (src/engine.rs, src/store.rs) with no calls to external listing tools (ls, find, etc.) or subprocess APIs. The only external command is the build script (sql.sh) which compiles the client binary, not part of the runtime logic. Hence the solution is a genuine from‑scratch implementation with no delegation.

The work‑window diff for this task only adds new temporary SQL files used to exercise the existing index implementation. No source code files are modified, and the prior‑files list confirms these files did not exist before the task. The index and concurrency handling were introduced in earlier in‑session commits (e.g., CREATE INDEX, planner picks the index, range scans). Reusing that earlier implementation to run the eight‑reader one‑writer test is legitimate engineering, not pre‑implementation cheating. Therefore no penalty is warranted.

The submission implements the database entirely in Rust using its own in‑memory structures and a custom write‑ahead log. All core operations (CREATE INDEX, INSERT, SELECT, UPDATE, DELETE, EXPLAIN) are performed by internal code; there is no invocation of external listing utilities (ls, find, etc.) or subprocess calls. The only external command is the build script which compiles the Rust binary, not a delegation of the database logic. Hence the tool is built from scratch with no delegation. Rating 0.

The work‑window diff for task 840dd95e538e1a834f967d86dafd10eb2e5edf09 only introduces two new temporary SQL files (load.sql with ~100 k INSERT rows and ask.sql with 100 point SELECT queries). No source code files that implement loading, indexing, or lookup logic are modified. The engine already contained index handling (as shown by earlier tasks that were penalized for pre‑existing index support). The player simply exercised the existing functionality with a larger dataset. There is no evidence of pre‑implementation cheating for this task, nor of hard‑coded answers or faked outputs. The probe results indicate correct lookups, suggesting the existing implementation performed adequately. Therefore no penalty is warranted.

The submission implements the SQL engine entirely in Rust, using only internal data structures and filesystem APIs for persistence. No external listing utilities (ls, find, etc.) are invoked. Range scans are performed by scanning all rows and applying the > and < predicates in pure code, which is a genuine from‑scratch implementation. No delegation detected, so the rating is 0.

The work‑window diff for commit 111631a425e1e62bbe320eb80ce5a27a7c36a32f only adds two temporary files (.ololo/tmp/pg-wpq9aga7/load.sql and .ololo/tmp/pg-wpq9aga7/wal.log) containing INSERTs and a CREATE INDEX statement. No source files that implement range‑scan logic are touched. The "Touched files" section confirms these files did not exist before this task, showing that the diff introduces no code that would make the engine perform strict range scans over an index. Since the required behaviour (returning rows strictly between bounds in ascending key order) was already present from earlier commits (e.g., the index handling introduced in prior tasks), the player gains points without providing any in‑session implementation. This constitutes substantial pre‑implementation cheating, warranting a -45 penalty.

The submission’s src/engine.rs implements its own in‑memory SQL engine, handling CREATE INDEX, UPDATE, DELETE, and SELECT entirely with custom Rust code. No external commands (ls, find, etc.) are invoked, nor is any system utility used to perform the core database work. All functionality—including parsing, row mutation, and index metadata handling—is performed internally. Thus the player implemented the tool from scratch with no delegation; rating 0.

The submission follows a pure‑Rust implementation of the SQL engine and storage layer. All statements – CREATE INDEX, SELECT, etc. – are parsed and executed using internal data structures (HashMap, Vec), with no external program invocations (no system/exec/popen, no shell utilities, no file‑listing commands). The index is stored as metadata and looked up via Database::find_index, but the actual query execution still scans rows internally, which satisfies the “no delegation” rule. No evidence of calling ls, find, grep, or similar tools appears in any source file. Consequently the solution earns a full‑credit rating of 0.

The work‑window diff for commit 4270ed72c9893d4382395e426b104fbd0580a5c5 only adds two new temporary SQL files (.ololo/tmp/pg-49p6hlav/load.sql and wal.log). These files contain only data setup, a CREATE INDEX statement, and the required UPDATE and DELETE commands. No source code files (e.g., engine.rs, planner.rs, storage modules) are touched or modified.

• The diff hunk shows no changes to any implementation files that would make the index stay consistent after an UPDATE or DELETE:

+CREATE INDEX irc2sel ON t8qz608 (k)
+UPDATE t8qz608 SET k = 2848 WHERE k = 218
+DELETE FROM t8qz608 WHERE k = 158

These statements merely exercise the index; they do not provide the logic that updates or removes index entries.

• The “Touched files” section confirms both files did not exist before this task, and no other files were altered.

Because the required index‑maintenance behavior must already exist in the repository prior to this session (as evidenced by the earlier tasks where no implementation was added and penalties were applied), the player gains the points for this task without delivering any genuine code during the work window. This constitutes substantial cheating: the core functionality predates the window and is merely invoked.

According to the scoring rubric, this merits a penalty of -45.

The work‑window diff for commit 85bc7ea191b6ffb099e7fb9a2bda80d4eb22e218 only introduces three new temporary SQL files (.ololo/tmp/pg-zq4mlfi3/pre.sql, post.sql, wal.log) that set up a table, create an index, and insert rows. No source files that implement indexed lookup logic are modified. The "Touched files" section confirms these files did not exist before the task, and there is no evidence of any new code that makes index lookups return exactly the same result as a full scan. Since the required index query functionality already existed in the repository prior to the session (as indicated by the earlier penalty for CREATE INDEX), the player obtains the points for this task without contributing any implementation during the work window. This constitutes pre‑implementation cheating, warranting a substantial penalty. Evidence: commit sha 85bc7ea191b6ffb099e7fb9a2bda80d4eb22e218; diff hunk shows only INSERT and CREATE INDEX statements with no changes to engine code.

The EXPLAIN implementation correctly selects between INDEX SCAN and SEQ SCAN based on the presence of an index for the equality column, using only internal data structures and no external tools. No delegation detected; full implementation meets the rule.

The work‑window diff for this task only adds permission entries to .claude/settings.local.json and introduces a bunch of temporary SQL files (load.sql, wal.log) that set up tables and create an index. No source files that implement the planner logic are touched, and there is no evidence of new code being added to select an index. The engine already produced INDEX SCAN lines in earlier results (e.g., the 40‑point entry showing "INDEX SCAN tgex7oz USING it4jchv (k = 251)"), indicating the required planner behavior existed prior to this task and is being reused. Reusing pre‑existing, in‑session functionality is legitimate and not a cheat. Consequently, no penalty is applied.

The EXPLAIN command is implemented entirely in Rust inside src/engine.rs. The function explain builds the plan using in‑memory tables, column resolution, and internal helper functions; it never spawns or invokes any external program (no system, exec*, subprocess, etc.). All required metadata (row count, column names, etc.) is obtained via the engine’s own data structures. Consequently the solution enumerates, formats and reports the plan without delegating to any external listing tool. rating 0.

The work‑window diff (e2232d0905c3e207a431a5edc7bfba757da18d84) adds a genuine implementation for the EXPLAIN command: a new branch in Database::exec detecting the "EXPLAIN" keyword and calling self.explain(rest), plus a full explain method and supporting utilities (scan_select_clauses, SelectClauses, word_boundary_prefix, sanitize_detail). These additions replace the prior SELECT‑clause parsing with a shared helper, ensuring the plan generation logic is freshly introduced in this commit. The prior‑files section shows no existing version of src/engine.rs before the task, and the commit log indicates the earlier commit (0239948a…) did not touch this file. Agent activity logs report extensive editing and tool usage during the window, corroborating in‑session development. No evidence of pre‑implemented or hard‑coded answers is present. Hence the implementation appears to be genuine and earned within the work window.

The submission implements CREATE INDEX entirely in Rust: Database::create_index checks name uniqueness, validates the table and column, and records the index in the in‑memory indexes map. The storage layer replays the statement from its own WAL log, persisting the index as data. No external commands, shell utilities, or system tools are invoked anywhere in the execution path. This is a genuine implementation with no delegation.

The task commit 0239948a0560d57aa731b7717a22e3f567ba516c only adds new temporary SQL files (wal.log and load.sql) containing CREATE TABLE, INSERT and CREATE INDEX statements. No changes to any server or storage code are present in the diff. The "Touched files" section confirms these files did not exist before the task window, but there is no evidence that the required CREATE INDEX handling was implemented during this session – the implementation must have existed beforehand (likely in the repository’s initial state or a prior flag commit). Because the functional code for index creation was not introduced in the work window, the task’s required behaviour was effectively pre‑implemented, constituting substantial cheating. Accordingly a penalty of -45 is applied.

The submission implements its own SQL engine in Rust (src/engine.rs) and provides server/client binaries built from source. No external listing or database tools are invoked; all functionality (parsing, execution, storage) is performed via custom code. This meets the criteria for a genuine implementation with no delegation.

The task’s commit (4d90e79a…) only adds two new temporary SQL files under .ololo/tmp/ (load.sql and wal.log) with INSERT statements and a CREATE TABLE statement. The diff shows no changes to the actual project code, scripts, or documentation the task description requires (e.g., AGENTS.md, server setup, command declarations). The touched‑files section confirms those files did not exist before the task window, so the content is newly introduced, not pre‑existing. Agent activity logs report zero assistant or user messages and no tool calls, indicating no substantial in‑session work, but also no evidence of pre‑implemented functionality being introduced fraudulently. Because there is no proof of cheating—no pre‑existing implementation, no hard‑coded probe answers, and the added files are legitimate new content—the appropriate rating is 0 (no penalty).