source: docs/P4-Prototype/PrototypeImplementation.md@ df05838

main
Last change on this file since df05838 was df05838, checked in by Stefan <trsunovstefan@…>, 3 weeks ago

Zip files
  • Property mode set to 100644
File size: 7.7 KB
Line 
1= Prototype Implementation =
2
3The prototype is a Go command-line application in
4[https://github.com/StefanTrsunov/bp/tree/main/server server/] that works against the `project`
5schema in PostgreSQL. It implements all seven use cases from
6[https://github.com/StefanTrsunov/bp/blob/main/docs/P3-UseCaseModel/UseCaseModel.md UseCaseModel]
7– the rubric requires at least three – with every database access shown as real, executed SQL.
8An auxiliary program in [https://github.com/StefanTrsunov/bp/tree/main/bots bots/] simulates a
9live market so prices move while the prototype is running.
10
11Build, configure, run and test instructions:
12[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/BuildInstructions.md BuildInstructions].
13
14All pages listed below, together with the screenshots of each run, are kept in the project's
15GitHub repository, [https://github.com/StefanTrsunov/bp StefanTrsunov/bp], under
16`docs/P4-Prototype/`.
17
18== Implemented use-cases ==
19
20||=Page=||=Use-case=||=Source=||
21||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0001Implementation.md UseCase0001Implementation]||Register a new account||[https://github.com/StefanTrsunov/bp/blob/main/server/auth.go server/auth.go]||
22||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0002Implementation.md UseCase0002Implementation]||Log in||[https://github.com/StefanTrsunov/bp/blob/main/server/auth.go server/auth.go]||
23||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0003Implementation.md UseCase0003Implementation]||Deposit virtual funds||[https://github.com/StefanTrsunov/bp/blob/main/server/account.go server/account.go]||
24||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0004Implementation.md UseCase0004Implementation]||Place market BUY order||[https://github.com/StefanTrsunov/bp/blob/main/server/trade.go server/trade.go]||
25||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0005Implementation.md UseCase0005Implementation]||Place market SELL order||[https://github.com/StefanTrsunov/bp/blob/main/server/trade.go server/trade.go]||
26||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0006Implementation.md UseCase0006Implementation]||View portfolio and history||[https://github.com/StefanTrsunov/bp/blob/main/server/portfolio.go server/portfolio.go]||
27||[https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/UseCase0007Implementation.md UseCase0007Implementation]||Manage watchlist||[https://github.com/StefanTrsunov/bp/blob/main/server/watchlist.go server/watchlist.go]||
28
29Each page mirrors its P3 use-case page and adds the actual SQL emitted by the Go code plus a
30screenshot of the corresponding run against the live database. The screenshots are committed
31alongside the pages, in
32[https://github.com/StefanTrsunov/bp/tree/main/docs/P4-Prototype/screenshots docs/P4-Prototype/screenshots/].
33
34== What the prototype demonstrates about the database design ==
35
36 * '''The current price is never stored as a column.''' It is always the price of the most recent
37 row in `market_trades`, read through the `v_latest_prices` view. Both the user's own fills and
38 the bot's simulated trades feed the same table, so there is exactly one definition of "the
39 price".
40 * '''Money movements are transactional.''' Buying touches five tables – `orders`, `users`,
41 `holdings`, `transactions`, `market_trades` – inside one transaction. A failed balance check
42 rolls the whole thing back: after a rejected purchase there is no order row, no ledger entry
43 and no holding. This is verified in the failure-path tests in
44 [https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/BuildInstructions.md BuildInstructions].
45 * '''Constraints do real work.''' `UNIQUE (user_id, crypto_id)` on `holdings` is what makes the
46 `INSERT … ON CONFLICT DO UPDATE` upsert possible, so the weighted-average entry price is
47 recomputed by the database in one statement instead of by a read-modify-write in application
48 code.
49 * '''No identifiers are ever typed.''' Markets are listed with their prices before any choice is
50 made, and everything else is selected by symbol.
51
52== Known limitations ==
53
54Deliberately out of scope for a first prototype, and the natural content of the later phases:
55
56 * Only `market` orders execute. `limit` is accepted by the schema (`orders.type`) but the
57 matching logic is not implemented.
58 * Passwords are SHA-256 without a salt. Adequate to demonstrate that the password itself is
59 never stored; not adequate for real use. A proper password hash belongs in P9 (security).
60 * Money is handled as `float64` in Go while the database columns are `numeric`. All arithmetic
61 that must be exact – the weighted average – is done in SQL for that reason, but the Go side
62 would need a decimal type for real use.
63 * There is no connection pooling configuration and no explicit isolation level; both are P8
64 topics.
65== AI usage ==
66
67AI was used in this phase and is logged in full, per the course rule for P1 onward.
68
69 * '''Phase log:'''
70 [https://github.com/StefanTrsunov/bp/blob/main/docs/P3-UseCaseModel/UseCaseModelAIUsage.md UseCaseModelAIUsage.md]
71 – service used, what the AI produced, and what I decided myself.
72 * '''Full conversation transcript:'''
73 [https://github.com/StefanTrsunov/bp/blob/main/docs/P1-ConceptualModel/ERModelAIUsage.md ERModelAIUsage.md]
74 – the same conversation produced the P1–P4 artefacts, so the complete prompt/response log is
75 kept in one place. Direct links:
76 [https://github.com/StefanTrsunov/bp/blob/main/docs/P1-ConceptualModel/ERModelAIUsage.md#session-1--2026-04-21 Session 1 – 2026-04-21],
77 [https://github.com/StefanTrsunov/bp/blob/main/docs/P1-ConceptualModel/ERModelAIUsage.md#session-2--2026-08-06--2026-08-07 Session 2 – 2026-08-06/07].
78
79'''Service:''' Claude Code (Anthropic), https://claude.com/claude-code – Claude subscription,
80model Claude Opus 4.7 (1M context).
81
82'''In short:''' the AI proposed the actor taxonomy and drafted the seven use cases with their SQL
83in session 1. In session 2 the use-case model itself was '''not''' changed – the only work was
84re-executing every scenario, including the failure paths, against a live PostgreSQL 16 database.
85
86== AI usage ==
87
88AI was used in this phase and is logged in full, per the course rule for P1 onward.
89
90 * '''Phase log:'''
91 [https://github.com/StefanTrsunov/bp/blob/main/docs/P4-Prototype/PrototypeImplementationAIUsage.md PrototypeImplementationAIUsage.md]
92 – service used, the bugs found and fixed, the test evidence, and what I decided myself.
93 * '''Full conversation transcript:'''
94 [https://github.com/StefanTrsunov/bp/blob/main/docs/P1-ConceptualModel/ERModelAIUsage.md ERModelAIUsage.md]
95 – the same conversation produced the P1–P4 artefacts, so the complete prompt/response log is
96 kept in one place. Direct links:
97 [https://github.com/StefanTrsunov/bp/blob/main/docs/P1-ConceptualModel/ERModelAIUsage.md#session-1--2026-04-21 Session 1 – 2026-04-21],
98 [https://github.com/StefanTrsunov/bp/blob/main/docs/P1-ConceptualModel/ERModelAIUsage.md#session-2--2026-08-06--2026-08-07 Session 2 – 2026-08-06/07].
99
100'''Service:''' Claude Code (Anthropic), https://claude.com/claude-code – Claude subscription,
101model Claude Opus 4.7 (1M context).
102
103'''In short:''' session 1 rewrote the existing Chi/HTTP backend as the CLI prototype covering
104UC0001–UC0007 and added the market bot. Session 2 was a review pass I asked for, which found and
105fixed three bugs – a path-resolution bug that made the documented build instructions fail, an
106infinite loop at end of input, and an error check in the wrong order that misreported database
107failures as "Insufficient holding" – and replaced the read-modify-write holding update with a
108single `INSERT … ON CONFLICT DO UPDATE`.
Note: See TracBrowser for help on using the repository browser.