Learn how to design large-scale systems. Prep for the system design interview. Includes Anki flashcards.
This report summarizes scanner evidence for donnemartin/system-design-primer, a Python project with 373,697 GitHub stars. SynthScan examined 14,345 lines of code across 52 source files, recording 66 pattern matches distributed across 4 syntactic categories. The legacy adjusted pattern signal is 10.7 (Moderate pattern signal); it is not an authorship estimate.
Use the findings to ask whether maintainers can explain intent, verify dependencies, simplify unnecessary scaffolding, and focus review effort. Risk Payload v1 adds ownership, supply-chain, over-engineering, and review-effort vectors when available. These are prompts for human verification, not probabilities, security findings, or measured maintenance costs.
Use each vector to guide manual verification of the underlying findings.
Can maintainers explain intent, assumptions, and trade-offs? 49 finding(s).
Are imports declared and package/API names verified? 0 finding(s).
Are wrappers, guards, and repeated structures necessary? 27 finding(s).
Which changes need focused human review? 66 finding(s).
This chart tracks the legacy adjusted pattern score across scan runs. Changes can reflect source changes, scan coverage, or detector/scoring versions; they do not measure AI adoption or prove that a team refactored code. Compare runs only when their scoring versions are compatible. The dashed line tracks the raw pattern-hit count.
Groups findings by configured severity weight. Severity is not a confidence estimate, security rating, or proof that a package is missing. Verify imports against the project's manifests and inspect each finding in its local design context.
This horizontal bar chart shows where configured pattern scores accumulate across directories. Treat the bars as locations to inspect, not as evidence of authorship or code quality. Use the file-level findings to decide whether a directory needs a focused ownership, dependency, complexity, or review check.
The scanner identified 66 distinct pattern matches across 4 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a detector match to inspect in context. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.
Reading the findings table: The Severity column indicates the configured finding weight (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — legacy comment-context matches receive a ×1.5 score weight. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier under the legacy scoring model.
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| HIGH | solutions/system_design/query_cache/README.md | 0 | get the stored query result from the cache. accessing a node updates its position to the front of the lru list. | STRING |
| HIGH | …ions/system_design/query_cache/query_cache_snippets.py | 0 | get the stored query result from the cache. accessing a node updates its position to the front of the lru list. | STRING |
| HIGH | solutions/object_oriented_design/lru_cache/lru_cache.py | 0 | get the stored query result from the cache. accessing a node updates its position to the front of the lru list. | STRING |
| HIGH | solutions/system_design/query_cache/README.md | 0 | set the result for the given query key in the cache. when updating an entry, updates its position to the front of the lr | STRING |
| HIGH | …ions/system_design/query_cache/query_cache_snippets.py | 0 | set the result for the given query key in the cache. when updating an entry, updates its position to the front of the lr | STRING |
| HIGH | solutions/object_oriented_design/lru_cache/lru_cache.py | 0 | set the result for the given query key in the cache. when updating an entry, updates its position to the front of the lr | STRING |
| HIGH | solutions/system_design/mint/README.md | 0 | return the year and month portions of the timestamp. | STRING |
| HIGH | solutions/system_design/mint/mint_mapreduce.py | 0 | return the year and month portions of the timestamp. | STRING |
| HIGH | solutions/system_design/pastebin/pastebin.py | 0 | return the year and month portions of the timestamp. | STRING |
| HIGH | solutions/system_design/pastebin/README.md | 0 | return the year and month portions of the timestamp. | STRING |
| HIGH | solutions/system_design/pastebin/README-zh-Hans.md | 0 | return the year and month portions of the timestamp. | STRING |
| HIGH | solutions/system_design/pastebin/pastebin.py | 0 | parse each log line, extract and transform relevant lines. emit key value pairs of the form: (2016-01, url0), 1 (2016-01 | STRING |
| HIGH | solutions/system_design/pastebin/README.md | 0 | parse each log line, extract and transform relevant lines. emit key value pairs of the form: (2016-01, url0), 1 (2016-01 | STRING |
| HIGH | solutions/system_design/pastebin/README-zh-Hans.md | 0 | parse each log line, extract and transform relevant lines. emit key value pairs of the form: (2016-01, url0), 1 (2016-01 | STRING |
| HIGH | solutions/system_design/pastebin/pastebin.py | 0 | sum values for each key. (2016-01, url0), 2 (2016-01, url1), 1 | STRING |
| HIGH | solutions/system_design/pastebin/README.md | 0 | sum values for each key. (2016-01, url0), 2 (2016-01, url1), 1 | STRING |
| HIGH | solutions/system_design/pastebin/README-zh-Hans.md | 0 | sum values for each key. (2016-01, url0), 2 (2016-01, url1), 1 | STRING |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | README.md | 226 | ### Step 1: Outline use cases, constraints, and assumptions | COMMENT |
| LOW | README.md | 239 | ### Step 2: Create a high level design | COMMENT |
| LOW | README.md | 246 | ### Step 3: Design core components | COMMENT |
| LOW | README.md | 259 | ### Step 4: Scale the design | COMMENT |
| LOW | README.md | 378 | ### Step 1: Review the scalability video lecture | COMMENT |
| LOW | README.md | 390 | ### Step 2: Review the scalability article | COMMENT |
| LOW | solutions/system_design/twitter/README.md | 7 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/twitter/README.md | 92 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/twitter/README.md | 98 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/twitter/README.md | 222 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/query_cache/README.md | 5 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/query_cache/README.md | 57 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/query_cache/README.md | 63 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/query_cache/README.md | 211 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/mint/README.md | 5 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/mint/README.md | 79 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/mint/README.md | 85 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/mint/README.md | 326 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/web_crawler/README.md | 5 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/web_crawler/README.md | 68 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/web_crawler/README.md | 74 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/web_crawler/README.md | 255 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/pastebin/README.md | 7 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/pastebin/README.md | 78 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/pastebin/README.md | 84 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/pastebin/README.md | 234 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/sales_rank/README.md | 5 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/sales_rank/README.md | 69 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/sales_rank/README.md | 75 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/sales_rank/README.md | 238 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/scaling_aws/README.md | 5 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/scaling_aws/README.md | 63 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/scaling_aws/README.md | 69 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/scaling_aws/README.md | 136 | ## Step 4: Scale the design | COMMENT |
| LOW | solutions/system_design/social_graph/README.md | 5 | ## Step 1: Outline use cases and constraints | COMMENT |
| LOW | solutions/system_design/social_graph/README.md | 49 | ## Step 2: Create a high level design | COMMENT |
| LOW | solutions/system_design/social_graph/README.md | 55 | ## Step 3: Design core components | COMMENT |
| LOW | solutions/system_design/social_graph/README.md | 249 | ## Step 4: Scale the design | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | solutions/system_design/mint/README.md | 292 | def handle_budget_notifications(self, key, total): | CODE |
| LOW | solutions/system_design/mint/mint_mapreduce.py | 20 | def handle_budget_notifications(self, key, total): | CODE |
| LOW | solutions/system_design/mint/README-zh-Hans.md | 293 | def handle_budget_notifications(self, key, total): | CODE |
| LOW | …ions/system_design/web_crawler/web_crawler_snippets.py | 18 | def reduce_priority_link_to_crawl(self, url): | CODE |
| LOW | …ions/system_design/web_crawler/web_crawler_snippets.py | 22 | def extract_max_priority_page(self): | CODE |
| LOW | solutions/system_design/web_crawler/README.md | 118 | def reduce_priority_link_to_crawl(self, url) | CODE |
| LOW | solutions/system_design/web_crawler/README.md | 122 | def extract_max_priority_page(self): | CODE |
| LOW | solutions/system_design/web_crawler/README-zh-Hans.md | 116 | def reduce_priority_link_to_crawl(self, url) | CODE |
| LOW | solutions/system_design/web_crawler/README-zh-Hans.md | 120 | def extract_max_priority_page(self): | CODE |
| LOW | …ions/object_oriented_design/call_center/call_center.py | 121 | def dispatch_queued_call_to_newly_freed_employee(self, call, employee): | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | generate-epub.sh | 37 | # Check if dependencies exist | COMMENT |