And My Line From Two Days Ago, "Low Switching Cost Is the Most Expensive Illusion," Holds Harder Now — Late on August 12 into the early hours of August 13 Beijing time, DeepSeek took V4-Pro to GA. The manner: no launch blog, no technical report, and to this day no 0813 entry in the official changelog — the newest entry there is still V4-Flash-0731 from July 31. It was first noticed by third parties when the model version string changed on the API docs and pricing pages; the official benchmark chart went out through DeepSeek's official WeChat group, then into Reddit (post since deleted) and an ASCII table on Hacker News. But this was not zero announcement: DeepSeek did post a short notice on its own site — now fully available across web, app and API, feedback welcome — and the chart carried official branding. The accurate description is that the announcement was small enough to require community archaeology. Sources: DeepSeek API docs and pricing pages, DeepSeek changelog (the 2026-04-24 and 2026-07-31 entries), DeepSeek's Claude Code and Codex integration docs, the Hugging Face deepseek-ai repo listing, Global Times (8/13), Simon Willison (8/12), Unite.AI (8/12), the OpenRouter model page, Reddit and Hacker News reposts, Anthropic's pricing page and Claude Code documentation, Sina/Securities Times/Wallstreetcn (6/30, peak-hour pricing) and aitoollab (8/6), DeepSeek's 2025-02-25 and 2026-06-29 pricing notices, and Nicolas Bustamante's "Model-Harness Fit" (5/3). Three claims circulating in Chinese coverage need dismantling, one of which I nearly wrote myself. First, "it adds Anthropic protocol compatibility" is wrong — that endpoint (api.deepseek.com/anthropic) shipped on April 24 with V4, and the Responses API plus Codex adaptation shipped July 31 with Flash-0731. Neither has anything to do with this GA. Second, "architecture and parameters unchanged, all gains from post-training" is not an official statement — DeepSeek wrote that only about Flash (the 7/31 changelog reads "keeps the same model architecture and size… and was only re-post-trained") and said nothing at all about Pro: no changelog entry, no model card, no technical report. Commentators inferred it from the Flash precedent plus unchanged price, context and max output; even the 1.6T/49B figures are assumptions inherited from the April preview card. Worth adding: producing a nearly fivefold jump on DeepSWE, from 12.8 to 62.7 against the April preview, through post-training alone makes that community inference more questionable, not less — which is exactly why I won't say it on DeepSeek's behalf. Third, "0813 is open source" is wrong — precisely, this build has no open weights; the V4-Pro weights on Hugging Face are the June 22 snapshot, and there is no 0813 repo. DeepSeek's own API exposes only the string deepseek-v4-pro (the docs say it "has been updated to 0813"); the versioned slug exists only on OpenRouter. The benchmarks (DeepSWE 62.7, NL2Repo 61.5, DSBench-Hard 67.2) are self-reported and have no third-party replication to date. Now the substance: this looks like it dismantles my judgment from two days ago, and actually welds it tighter. On August 11 (ENTRY 121) I wrote a hard line — "low switching cost is this cycle's most expensive illusion." Someone will now say: Chinese models have been Anthropic-protocol-compatible for months, you point Claude Code at a different base_url, so the cost is zero. My answer is that protocol compatibility removes precisely the least valuable part of a migration. First, how far from drop-in it actually is: DeepSeek's own integration doc prescribes nine environment variables; Codex isn't env vars at all but a ~/.codex/models.json declaring context window, effort levels and tool-call formats; image input is unsupported, which breaks Claude Code's screenshot and paste workflow outright; cache_control is ignored, so Anthropic-style explicit prompt caching transfers not at all; and the Responses API is stateless — the server stores nothing and you resend the full history every turn, which is real engineering work. One more layer to state plainly: Anthropic's own documentation says it "doesn't support routing Claude Code to non-Claude models through any gateway" — neither permission nor prohibition; I make no legal judgment, but I evaluate it as a configuration carrying no vendor support commitment. The real cost sits somewhere with a measured number: harness fit. On Terminal-Bench 2.0, the same model — Claude Opus 4.6 — scores 79.8% inside ForgeCode and 75.3% inside Capy: not a word of the model changed, only the shell, and 4.5 percentage points separate them; Cursor moved from Top 30 to Top 5 on that same benchmark by changing only the harness (Nicolas Bustamante, "Model-Harness Fit," May 3). The mechanism is straightforward: models are post-trained against specific tool surfaces, and dropping one into a different shell leaks a slice of its capability. Here I owe an honest correction to my own argument from two days ago: in ENTRY 121 I used Lindy's six-to-nine-month migration as evidence, but that migration predates protocol compatibility — Lindy moved to DeepSeek V4, and the /anthropic endpoint only appeared on April 24; working back from CNBC's June 26 report, the effort started in late 2025. So it cannot answer "how much cost remains once compatibility exists." I can use it as an upper bound on cost, not as evidence that the plumbing was always the cheap part. What actually supports my claim is the harness-fit measurement. Protocol compatibility collapses plumbing cost to near zero, and plumbing was never the moat. Said more precisely than two days ago: the switching cost is not "the interface doesn't connect," it is "once the interface connects, you still have to re-tune the model into being the model your workflow expects." Second thread, pricing — but first I have to narrow my own analogy. DeepSeek held V4-Pro at ¥3/¥6 per million tokens (¥0.025 on cache hits), while its pricing page carries an official notice posted on August 6 — not on GA day, seven days earlier: "We plan to raise the overall pricing for DeepSeek API services in the near future, with a significant increase expected. Please plan your usage accordingly. The specific pricing plan will be subject to official notice." No date, no magnitude — do not read it as a scheduled increase. And the full picture matters: ¥3/¥6 is itself a 75%-off promotional rate, made permanent on May 22 rather than expiring May 31; and DeepSeek has raised prices before — when the launch promotion ended on February 25, 2025, deepseek-chat went from ¥1/¥2 to ¥2/¥8, and in late June 2026 it announced peak-hour pricing at 2x for 09:00–12:00 and 14:00–18:00 Beijing time, though whether that is currently in force is genuinely unclear (see below). So this is not "a company that only ever cut prices raising them for the first time"; it is another step in the same direction, part of which is merely discount reversion rather than a net increase. And the relationship to my July 28 entry (ENTRY 114) has to be stated accurately: 114 was about open weights being released while pricing power is retained — K3 gave away weights for distribution and raised its API roughly 3.7x eleven days before the weight release. 0813 has no open weights, so this is not an independent sample of 114 but a mirror image of it: K3 was open weights plus a price rise; DeepSeek here is closed weights plus a pre-announced price rise. The only thing they share is that neither surrendered the right to set the price. Free web and app access is not free distribution — that is not open weights. Now the correction I owe publicly. On August 1 (ENTRY 118) I wrote: "Anthropic mirrors this: Sonnet 5 flagged a return to $3/$15 after 8/31 (single-source)." That flagged increase has been explicitly cancelled — Anthropic's pricing page now states that $2/$10 "is now the standard price" and that the September 1 increase "will not occur." I did label it single-source at the time, but labeling is not absolution; a correction owed is a correction made: Sonnet 5 is $2/$10 as standard. The parent judgment — stratified pricing, not a price war — is unaffected: the top tier (Fable 5 and Mythos 5 at $10/$50, Opus 5 at $5/$25) is still collecting rent, and what got cancelled was a mid-tier increase, which if anything strengthens the "the middle is where it hurts" half of that claim. The ledger entry for 118 has been annotated accordingly, before this entry went live. One measurement trap everyone is ignoring. People compute "how many times cheaper Chinese models are" from list prices per million tokens, but Anthropic's own pricing page states that Claude 4.7 and later models use a newer tokenizer producing approximately 30% more tokens for the same text. State that number's boundary precisely: it is a ratio between Anthropic's own two tokenizer generations, not a ratio between Anthropic and DeepSeek — a cross-vendor comparison needs both tokenizers counted on identical text, which I do not have. So the only conclusion I will draw is that per-token multiples are list multiples, directionally unfavorable to Claude, with no quantification from me. This is the same failure mode as my entry two days ago: taking the number that is easy to obtain and treating it as the number that is persuasive. There is also a contradiction I could not resolve and must disclose: Chinese media reported that peak-hour pricing took effect with V4 GA in mid-July, but DeepSeek's official pricing page today shows a single flat table with no peak/off-peak column, and the terms for peak, off-peak and time band appear nowhere on the site. If you run agentic workloads during Chinese business hours, that is potentially a 2x error, and I could not establish which account is correct. Two rulers for my own work. One: when a diligence deck says "we can switch substrates any time," the question "does the interface connect?" has become too cheap to spend time on — what to ask instead is how large your eval set is, whether your prompts are welded to one vendor's tool surface, and what you will measure to know how much you lost after switching. Anyone who cannot answer the third has never done a migration. Two: when assessing a Chinese model's cost advantage, compute list price and effective cost separately — tokenizer, cache-hit rate, peak-hour bands, and hosting location can each rewrite the multiple. On that last item I owe myself a note: in ENTRY 121 I wrote that "the same V4 Pro costs 4x more hosted in the US," but Together's $1.74/$3.48 happens to equal DeepSeek's undiscounted list level — so that may not be a US hosting premium at all, merely the un-discounted price, an ambiguity I did not see at the time. Rollback: the 0813 architecture figures (1.6T/49B) are inherited from the April preview card, DeepSeek published no model card or technical report for 0813, and "architecture unchanged" is a community inference rather than an official statement; the benchmarks are self-reported without third-party replication; the price-increase notice carries no date and no magnitude, and ¥3/¥6 is itself a discount made permanent; the current status of peak-hour pricing is contradicted between Chinese media and official docs and I could not verify it; the pre-discount nominal $1.74/$3.48 comes from a single SEO blog, is unconfirmed on DeepSeek's site, and is the same number as ENTRY 121's "4x US hosting premium," carrying a hosting-premium-versus-list-price ambiguity; Anthropic's language on pointing Claude Code at non-Claude models is "does not support," neither explicit permission nor prohibition, and I make no legal judgment; and the 4.5-point harness-fit figure comes from a single-source analysis dated early May, measuring the Opus 4.6 generation, with no updated data on whether harness adaptation has converged since Opus 5.
Falsifier: if within 12 months three or more US companies publicly complete a migration of a production coding agent from Anthropic or OpenAI to a Chinese model AND disclose a migration time under two months, then "the switching cost is in the harness, not the plumbing" is downgraded. The upgrade condition is deliberately not "nobody published, therefore it is true" — that is the exact fallacy I wrote about in ENTRY 121 (absence of reports is not absence of events) — and is instead a checkable positive signal: if within 12 months a harness or agent-framework vendor publishes benchmark regression figures for cross-model adaptation and that regression is still 3 percentage points or more, this judgment upgrades to verified. A half-progress report on ENTRY 118's falsifier: its wording was "if within three months Sol or Fable 5 class top-tier models are forced to cut prices." On the Anthropic side the top tier has not cut (Fable 5 and Mythos 5 still $10/$50, Opus 5 still $5/$25); on the Sol side I did not verify in this entry, so I report half the check and draw no conclusion.
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