Add sustainability statement (#703)

Author: shibatch

README.adoc

@@ -148,15 +148,123 @@ The software is distributed under the Boost Software License, Version
 http://www.boost.org/LICENSE_1_0.txt. Contributions to this project are
 accepted under the same license.
 
-SLEEF project aims to serve society as a whole, not just specific
-companies or organizations. We charge a fee for maintaining patches
-that are convenient only for your company.
-
-The fact that our software is released under an open source license
-only means that you can use the current and older versions of the
-software for free. If you want us to continue maintaining our
-software, you need to financially support our project. Please see
-our https://github.com/shibatch/nofreelunch?tab=coc-ov-file[Code of
-Conduct] or its https://youtu.be/35zFfdCuBII[introduction video].
+==== Building a Sustainable Future for Our Open Source Projects
+
+We believe that Free and Open Source Software (FOSS) is a wonderful
+ecosystem that allows anyone to use software freely. However, to
+maintain and enhance its value over the long term, continuous
+maintenance and improvement are essential.
+
+Like many FOSS projects, we face the challenge that long-term
+sustainability is difficult to achieve through the goodwill and
+efforts of developers alone. While the outputs of open-source projects
+are incorporated into the products of many companies and their value
+is rightfully recognized, the developers who create these outputs are
+not always treated as equal partners in the business world.
+
+A license guarantees the "freedom to use," but the spirit of the FOSS
+ecosystem is based on a culture of mutual respect and contribution
+built upon that freedom. We believe that accepting the "value" of a
+project's output while unilaterally refusing dialogue with its
+creators simply because they are individuals undermines the
+sustainability of this ecosystem. Such companies should not turn a
+blind eye to the reality that someone must bear the costs to make the
+cycle sustainable.
+
+This issue is not just about corporations; it reflects a deeper
+cultural expectation within the FOSS ecosystem itself. Over time, we
+have come to take for granted that everything in open source should be
+provided for free - not only the code, but also the ongoing effort to
+maintain and improve it. However, FOSS licenses guarantee the freedom
+to use and modify software; **they do not impose an obligation on
+developers to offer perpetual, unpaid maintenance**. When this
+distinction is overlooked, maintainers can end up burdened with work
+that was never meant to be an open-ended personal commitment. Such an
+imbalance not only discourages openness, but also undermines the
+sustainability of an ecosystem that has become a vital part of modern
+society.
+
+To explain the phenomenon occurring across the entire ecosystem:
+Developers write code they find useful and release it as FOSS. It
+gains popularity, and soon large corporations incorporate it into
+their products, reaping substantial profits. Requests for new features
+and fixes flood in, yet no financial support accompanies
+them. Eventually, the maintainer realizes there is no personal or
+professional benefit in responding to these unpaid demands. The skills
+required to develop popular FOSS are often in high demand in other
+fields as well. Ultimately, the maintainer burns out and the project
+is abandoned. This is the unsustainable cycle we are tackling.
+
+Within this unsustainable cycle, adopting FOSS into products while
+fully aware of this situation is hardly beneficial for either
+companies or the society at large. To make the cycle sustainable,
+everyone must recognize the reality that someone must bear the costs,
+and these costs are equivalent to what companies would need to develop
+and maintain comparable products. This project specifically requests
+companies profiting from our deliverables to contribute to maintaining
+the project.
+
+To be clear, **this is not a request for charity**; it is a proposal
+to manage the operational risk. This is a systemic challenge
+originating not from the developers, but from within the organizations
+that consume and whose business continuity depends on FOSS. Should a
+project be abandoned due to this unresolved problem, **the primary
+victims will be you, the company** that built its product on top of an
+unmaintained foundation, not the developers who can move on to other
+opportunities.
+
+==== Our Request for Support
+
+We request ongoing financial support from organizations that
+incorporate our project's deliverables into their products or services
+and derive **annual revenue exceeding US $1 million** from those
+products and services, to help cover the costs of maintenance and the
+development of new features. While this support is not a legal
+obligation, let us be clear: the license is a grant of permission to
+use our work, not a service contract obligating us to provide
+perpetual, unpaid labor. We consider it a fundamental business
+principle that to profit from a critical dependency while contributing
+nothing to its stability is an extractive and unsustainable practice.
+
+It is also crucial to recognize what "maintenance" truly entails. In a
+living software project, it is not merely about preserving the status
+quo of the current version. It is the continuous effort that leads to
+security patches, compatibility with new environments, and the very
+features that define future versions. Therefore, to claim satisfaction
+with an older version as a reason to decline support, while
+simultaneously benefiting from the ongoing development that produces
+newer, better versions, is a logically inconsistent position.
+
+This support must not be intended to benefit any particular company,
+but must support maintaining the project as a shared infrastructure
+that **benefits all users and the broader community**. Furthermore,
+this threshold is designed so that **individual developers,
+small-scale projects, and the majority of our users are not asked to
+pay**, while seeking appropriate support from companies that derive
+significant value from our project.
+
+We understand that corporate procurement processes were not designed
+with FOSS sustainability in mind. We are committed to finding a
+practical path forward, but your partnership is essential in
+structuring a financial relationship that aligns with your standard
+corporate procedures. Our mutual goal is to treat this partnership as
+a conventional operational expense, removing your internal barriers
+and making sustainability a straightforward business practice.
+
+Our goal is to maintain this project stably over the long term and
+make it even more valuable for all users. In an industry where many
+projects are forced to abandon FOSS licenses, our preference is to
+continue offering this project under a true open-source
+license. However, the long-term viability of this FOSS-first approach
+depends directly on the willingness of our commercial beneficiaries to
+invest in the ecosystem they rely on. We hope our collaborative
+approach can contribute to shaping a more balanced and enduring future
+for FOSS.
+
+For details, please see our
+https://github.com/shibatch/nofreelunch?tab=coc-ov-file[Code of
+Conduct] or its https://youtu.be/35zFfdCuBII[introduction video]. For
+reuse of this sustainability statement, see
+link:SUSTAINABILITY.md[SUSTAINABILITY.md].
 
 Copyright © 2010-2025 SLEEF Project, Naoki Shibata and contributors.

SUSTAINABILITY.md

@@ -0,0 +1,126 @@
+#### Building a Sustainable Future for Our Open Source Projects
+
+We believe that Free and Open Source Software (FOSS) is a wonderful
+ecosystem that allows anyone to use software freely. However, to
+maintain and enhance its value over the long term, continuous
+maintenance and improvement are essential.
+
+Like many FOSS projects, we face the challenge that long-term
+sustainability is difficult to achieve through the goodwill and
+efforts of developers alone. While the outputs of open-source projects
+are incorporated into the products of many companies and their value
+is rightfully recognized, the developers who create these outputs are
+not always treated as equal partners in the business world.
+
+A license guarantees the "freedom to use," but the spirit of the FOSS
+ecosystem is based on a culture of mutual respect and contribution
+built upon that freedom. We believe that accepting the "value" of a
+project's output while unilaterally refusing dialogue with its
+creators simply because they are individuals undermines the
+sustainability of this ecosystem. Such companies should not turn a
+blind eye to the reality that someone must bear the costs to make the
+cycle sustainable.
+
+This issue is not just about corporations; it reflects a deeper
+cultural expectation within the FOSS ecosystem itself. Over time, we
+have come to take for granted that everything in open source should be
+provided for free - not only the code, but also the ongoing effort to
+maintain and improve it. However, FOSS licenses guarantee the freedom
+to use and modify software; **they do not impose an obligation on
+developers to offer perpetual, unpaid maintenance**. When this
+distinction is overlooked, maintainers can end up burdened with work
+that was never meant to be an open-ended personal commitment. Such an
+imbalance not only discourages openness, but also undermines the
+sustainability of an ecosystem that has become a vital part of modern
+society.
+
+To explain the phenomenon occurring across the entire ecosystem:
+Developers write code they find useful and release it as FOSS. It
+gains popularity, and soon large corporations incorporate it into
+their products, reaping substantial profits. Requests for new features
+and fixes flood in, yet no financial support accompanies
+them. Eventually, the maintainer realizes there is no personal or
+professional benefit in responding to these unpaid demands. The skills
+required to develop popular FOSS are often in high demand in other
+fields as well. Ultimately, the maintainer burns out and the project
+is abandoned. This is the unsustainable cycle we are tackling.
+
+Within this unsustainable cycle, adopting FOSS into products while
+fully aware of this situation is hardly beneficial for either
+companies or the society at large. To make the cycle sustainable,
+everyone must recognize the reality that someone must bear the costs,
+and these costs are equivalent to what companies would need to develop
+and maintain comparable products. This project specifically requests
+companies profiting from our deliverables to contribute to maintaining
+the project.
+
+To be clear, **this is not a request for charity**; it is a proposal
+to manage the operational risk. This is a systemic challenge
+originating not from the developers, but from within the organizations
+that consume and whose business continuity depends on FOSS. Should a
+project be abandoned due to this unresolved problem, **the primary
+victims will be you, the company** that built its product on top of an
+unmaintained foundation, not the developers who can move on to other
+opportunities.
+
+#### Our Request for Support
+
+We request ongoing financial support from organizations that
+incorporate our project's deliverables into their products or services
+and derive **annual revenue exceeding US $1 million** from those
+products and services, to help cover the costs of maintenance and the
+development of new features. While this support is not a legal
+obligation, let us be clear: the license is a grant of permission to
+use our work, not a service contract obligating us to provide
+perpetual, unpaid labor. We consider it a fundamental business
+principle that to profit from a critical dependency while contributing
+nothing to its stability is an extractive and unsustainable practice.
+
+It is also crucial to recognize what "maintenance" truly entails. In a
+living software project, it is not merely about preserving the status
+quo of the current version. It is the continuous effort that leads to
+security patches, compatibility with new environments, and the very
+features that define future versions. Therefore, to claim satisfaction
+with an older version as a reason to decline support, while
+simultaneously benefiting from the ongoing development that produces
+newer, better versions, is a logically inconsistent position.
+
+This support must not be intended to benefit any particular company,
+but must support maintaining the project as a shared infrastructure
+that **benefits all users and the broader community**. Furthermore,
+this threshold is designed so that **individual developers,
+small-scale projects, and the majority of our users are not asked to
+pay**, while seeking appropriate support from companies that derive
+significant value from our project.
+
+We understand that corporate procurement processes were not designed
+with FOSS sustainability in mind. We are committed to finding a
+practical path forward, but your partnership is essential in
+structuring a financial relationship that aligns with your standard
+corporate procedures. Our mutual goal is to treat this partnership as
+a conventional operational expense, removing your internal barriers
+and making sustainability a straightforward business practice.
+
+Our goal is to maintain this project stably over the long term and
+make it even more valuable for all users. In an industry where many
+projects are forced to abandon FOSS licenses, our preference is to
+continue offering this project under a true open-source
+license. However, the long-term viability of this FOSS-first approach
+depends directly on the willingness of our commercial beneficiaries to
+invest in the ecosystem they rely on. We hope our collaborative
+approach can contribute to shaping a more balanced and enduring future
+for FOSS.
+
+For details, please see our [Code of
+Conduct](https://github.com/shibatch/nofreelunch?tab=coc-ov-file) or
+its [introduction video](https://youtu.be/35zFfdCuBII).
+
+---
+
+This sustainability statement is copyrighted by Naoki Shibata 2025.
+Licensed under [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/).
+
+If you agree with the purpose of this statement, you can copy the text
+into your project's README to help spread awareness. When doing so,
+please also include a file named `SUSTAINABILITY.md` within your
+repository that contains the statement and attribution.